Re: [time-nuts] Help Identifying this surplus Timing Module

[CubeCentral]

Bob, thank you so very much for this - I will share it with the owner of the 
module and let you know what he decides to do with it!
I so very much appreciate being able to pick y'all brains from time to time, 
and I just wanted to be sure to thank you!
Cheers!

-Randal   (at CubeCentral)

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob kb8tq
Sent: Saturday, May 12, 2018 08:39
To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
Subject: Re: [time-nuts] Help Identifying this surplus Timing Module

Hi

Ok, the gizmo on the front it an Altera CPLD. Not a lot of gates, so not a lot 
going on there. Whatever the real functions are, they are in the chip with no 
labeling. 

Even with the full information (let’s say): 

Takes in a 16 stream OC-blah blah and provides the following alarms on the 
status channel. Hookup up the data stream and backup to pins X and Y. Status 
alarms also come out on A, B, and C. Power is 12 V +/- 10% on pin M. Enable and 
control are on pins E,F,G. 

Unless you happen to be building an OC-3 system in the basement and have all 
the optical fiber stuff to do it …. not a lot of use. It is very similar to a 
lot of product I designed over the years. It likely does a great job in it’s 
intended OEM application.
It’s pretty much useless for anything more general purpose as it is right now.

Without a schematic, the source code for the DSP and CPLD  and the proper tool 
sets, not much you can modify it to do. Even with all that stuff, probably the 
best you could do is a fairly basic 1 pps in. to  38.88 MHz) / M  out PLL. 

Indeed this *is* where timing has gone over the last few decades. TimeNuts 
normally may not look at telecom timing as an exciting thing. There is a vast 
amount of gear that has been built to distribute signals inside these networks. 
As far as Crazy Bob at home is concerned, it’s all out of reach. It also is all 
designed for maintenance of data sync rather than time of day. It’s still very 
much time, just a different way of looking at it. 

Bob

> On May 11, 2018, at 11:45 PM, CubeCentral <cubecent...@gmail.com> wrote:
> 
> Thank you bob and Gary for your investigations!  I appreciate it!  Here are a 
> couple more views:
> 
> https://imgur.com/a/auWdXvq
> 
> "This is the picture with sticker removed.   The large IC at the back has its 
> label scratched off.  ... that was intentional, but he has a note saying it 
> is a member of Motorola DSP56300 family. It was likely purchased in 2010 
> based on an eBay invoice which has no date on it, but the scanned date was 
> Feb 2011."
> 
> If anyone else has any more ideas, I would gladly hear them!  Thanks again!
> 
>   -Randal   (at CubeCentral)
> 
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Gary 
> Chatters
> Sent: Friday, May 11, 2018 19:07
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] Help Identifying this surplus Timing Module
> 
> A little Googling found a two page datasheet.  It doesn't tell you much more 
> than what you already found out, but does have specifications.
> 
> I can't figure out the correct link to include here, but a Google search with 
> the string "ATiMe-s 38.88" (don't include the quotes) should bring up the 
> link in the first couple of hits.  It is a PDF at the www.sbtron.co.kr 
> website.
> 
> gc
> 
> On 05/11/2018 07:16 PM, CubeCentral wrote:
>> Hello All!
>> 
>> 
>> 
>> I would like to enlist your help in identifying this "surplus Timing
>> Module":  https://imgur.com/a/Psw8gP7
>> 
>> 
>> 
>> All the hints I've been given are:
>> 
>> - Purchased about a decade ago
>> 
>> - Might use a Motorola DSP as the processor
>> 
>> 
>> 
>> A quick google search lead me to a possible description:
>> 
>> "High speed, hitless, ultra low jitter timing module for OC-N line
>> interfaces:  The TF Systems / ATiMe-LC is a timing reference source 
>> for OC-N and STM-N interfaces. It complements TeraSync's central 
>> timing modules to provide a complete and redundant timing solution at the 
>> system level."
>> 
>> 
>> 
>> ...but I'm unsure if that is 100% the same module.  If you would like 
>> to get some different photos, please let me know and I will see what 
>> I can do.  Any thoughts or ideas would be greatly appreciated!  Thanks!
>> 
>> 
>> 
>> -Randal   (at CubeCentral)
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the i

Re: [time-nuts] Help Identifying this surplus Timing Module

[Bob kb8tq]

Hi

Ok, the gizmo on the front it an Altera CPLD. Not a lot of gates, so not a lot 
going 
on there. Whatever the real functions are, they are in the chip with no 
labeling. 

Even with the full information (let’s say): 

Takes in a 16 stream OC-blah blah and provides the following alarms on the 
status
channel. Hookup up the data stream and backup to pins X and Y. Status alarms 
also come
out on A, B, and C. Power is 12 V +/- 10% on pin M. Enable and control are on 
pins
E,F,G. 

Unless you happen to be building an OC-3 system in the basement and have all
the optical fiber stuff to do it …. not a lot of use. It is very similar to a 
lot of product
I designed over the years. It likely does a great job in it’s intended OEM 
application.
It’s pretty much useless for anything more general purpose as it is right now.

Without a schematic, the source code for the DSP and CPLD  and the proper tool 
sets, not much you can modify it to do. Even with all that stuff, probably the 
best you 
could do is a fairly basic 1 pps in. to  38.88 MHz) / M  out PLL. 

Indeed this *is* where timing has gone over the last few decades. TimeNuts 
normally may 
not look at telecom timing as an exciting thing. There is a vast amount of gear 
that 
has been built to distribute signals inside these networks. As far as Crazy Bob 
at
home is concerned, it’s all out of reach. It also is all designed for 
maintenance of 
data sync rather than time of day. It’s still very much time, just a different 
way of
looking at it. 

Bob

> On May 11, 2018, at 11:45 PM, CubeCentral <cubecent...@gmail.com> wrote:
> 
> Thank you bob and Gary for your investigations!  I appreciate it!  Here are a 
> couple more views:
> 
> https://imgur.com/a/auWdXvq
> 
> "This is the picture with sticker removed.   The large IC at the back has its 
> label scratched off.  ... that was intentional, but he has a note saying it 
> is a member of Motorola DSP56300 family. It was likely purchased in 2010 
> based on an eBay invoice which has no date on it, but the scanned date was 
> Feb 2011."
> 
> If anyone else has any more ideas, I would gladly hear them!  Thanks again!
> 
>   -Randal   (at CubeCentral)
> 
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Gary Chatters
> Sent: Friday, May 11, 2018 19:07
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] Help Identifying this surplus Timing Module
> 
> A little Googling found a two page datasheet.  It doesn't tell you much more 
> than what you already found out, but does have specifications.
> 
> I can't figure out the correct link to include here, but a Google search with 
> the string "ATiMe-s 38.88" (don't include the quotes) should bring up the 
> link in the first couple of hits.  It is a PDF at the www.sbtron.co.kr 
> website.
> 
> gc
> 
> On 05/11/2018 07:16 PM, CubeCentral wrote:
>> Hello All!
>> 
>> 
>> 
>> I would like to enlist your help in identifying this "surplus Timing
>> Module":  https://imgur.com/a/Psw8gP7
>> 
>> 
>> 
>> All the hints I've been given are:
>> 
>> - Purchased about a decade ago
>> 
>> - Might use a Motorola DSP as the processor
>> 
>> 
>> 
>> A quick google search lead me to a possible description:
>> 
>> "High speed, hitless, ultra low jitter timing module for OC-N line
>> interfaces:  The TF Systems / ATiMe-LC is a timing reference source for OC-N
>> and STM-N interfaces. It complements TeraSync's central timing modules to
>> provide a complete and redundant timing solution at the system level."
>> 
>> 
>> 
>> ...but I'm unsure if that is 100% the same module.  If you would like to get
>> some different photos, please let me know and I will see what I can do.  Any
>> thoughts or ideas would be greatly appreciated!  Thanks!
>> 
>> 
>> 
>> -Randal   (at CubeCentral)
>> 
> ___
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Re: [time-nuts] Help Identifying this surplus Timing Module

[CubeCentral]

Thank you bob and Gary for your investigations!  I appreciate it!  Here are a 
couple more views:

https://imgur.com/a/auWdXvq

"This is the picture with sticker removed.   The large IC at the back has its 
label scratched off.  ... that was intentional, but he has a note saying it is 
a member of Motorola DSP56300 family. It was likely purchased in 2010 based on 
an eBay invoice which has no date on it, but the scanned date was Feb 2011."

If anyone else has any more ideas, I would gladly hear them!  Thanks again!

-Randal   (at CubeCentral)


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Gary Chatters
Sent: Friday, May 11, 2018 19:07
To: time-nuts@febo.com
Subject: Re: [time-nuts] Help Identifying this surplus Timing Module

A little Googling found a two page datasheet.  It doesn't tell you much more 
than what you already found out, but does have specifications.

I can't figure out the correct link to include here, but a Google search with 
the string "ATiMe-s 38.88" (don't include the quotes) should bring up the link 
in the first couple of hits.  It is a PDF at the www.sbtron.co.kr website.

gc

On 05/11/2018 07:16 PM, CubeCentral wrote:
> Hello All!
> 
>   
> 
> I would like to enlist your help in identifying this "surplus Timing
> Module":  https://imgur.com/a/Psw8gP7
> 
>   
> 
> All the hints I've been given are:
> 
> - Purchased about a decade ago
> 
> - Might use a Motorola DSP as the processor
> 
>   
> 
> A quick google search lead me to a possible description:
> 
> "High speed, hitless, ultra low jitter timing module for OC-N line
> interfaces:  The TF Systems / ATiMe-LC is a timing reference source for OC-N
> and STM-N interfaces. It complements TeraSync's central timing modules to
> provide a complete and redundant timing solution at the system level."
> 
>   
> 
> ...but I'm unsure if that is 100% the same module.  If you would like to get
> some different photos, please let me know and I will see what I can do.  Any
> thoughts or ideas would be greatly appreciated!  Thanks!
> 
>   
> 
>  -Randal   (at CubeCentral)
> 
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Re: [time-nuts] Help Identifying this surplus Timing Module

[Gary Chatters]

A little Googling found a two page datasheet.  It doesn't tell you much 
more than what you already found out, but does have specifications.


I can't figure out the correct link to include here, but a Google search 
with the string "ATiMe-s 38.88" (don't include the quotes) should bring 
up the link in the first couple of hits.  It is a PDF at the 
www.sbtron.co.kr website.


gc

On 05/11/2018 07:16 PM, CubeCentral wrote:

Hello All!

  


I would like to enlist your help in identifying this "surplus Timing
Module":  https://imgur.com/a/Psw8gP7

  


All the hints I've been given are:

- Purchased about a decade ago

- Might use a Motorola DSP as the processor

  


A quick google search lead me to a possible description:

"High speed, hitless, ultra low jitter timing module for OC-N line
interfaces:  The TF Systems / ATiMe-LC is a timing reference source for OC-N
and STM-N interfaces. It complements TeraSync's central timing modules to
provide a complete and redundant timing solution at the system level."

  


...but I'm unsure if that is 100% the same module.  If you would like to get
some different photos, please let me know and I will see what I can do.  Any
thoughts or ideas would be greatly appreciated!  Thanks!

  


 -Randal   (at CubeCentral)


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Re: [time-nuts] Help Identifying this surplus Timing Module

[Bob kb8tq]

Hi

The big chip with the sticker on it is an Altera FPGA. A picture of the back
side might help a little (if there is anything on the back side …).

Simple answer - it’s a nice source of parts ….

Bob

> On May 11, 2018, at 7:16 PM, CubeCentral  wrote:
> 
> Hello All!
> 
> 
> 
> I would like to enlist your help in identifying this "surplus Timing
> Module":  https://imgur.com/a/Psw8gP7 
> 
> 
> 
> All the hints I've been given are:
> 
> - Purchased about a decade ago
> 
> - Might use a Motorola DSP as the processor
> 
> 
> 
> A quick google search lead me to a possible description:
> 
> "High speed, hitless, ultra low jitter timing module for OC-N line
> interfaces:  The TF Systems / ATiMe-LC is a timing reference source for OC-N
> and STM-N interfaces. It complements TeraSync's central timing modules to
> provide a complete and redundant timing solution at the system level."
> 
> 
> 
> ...but I'm unsure if that is 100% the same module.  If you would like to get
> some different photos, please let me know and I will see what I can do.  Any
> thoughts or ideas would be greatly appreciated!  Thanks!
> 
> 
> 
>-Randal   (at CubeCentral)
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

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Re: [time-nuts] Help Identifying this surplus Timing Module

[Bob kb8tq]

Hi

Given the frequency of the oscillator, it’s some sort of sync module for a 
telecom system. What data rate and what sort of coding …. who knows …

Bob

> On May 11, 2018, at 7:16 PM, CubeCentral  wrote:
> 
> Hello All!
> 
> 
> 
> I would like to enlist your help in identifying this "surplus Timing
> Module":  https://imgur.com/a/Psw8gP7 
> 
> 
> 
> All the hints I've been given are:
> 
> - Purchased about a decade ago
> 
> - Might use a Motorola DSP as the processor
> 
> 
> 
> A quick google search lead me to a possible description:
> 
> "High speed, hitless, ultra low jitter timing module for OC-N line
> interfaces:  The TF Systems / ATiMe-LC is a timing reference source for OC-N
> and STM-N interfaces. It complements TeraSync's central timing modules to
> provide a complete and redundant timing solution at the system level."
> 
> 
> 
> ...but I'm unsure if that is 100% the same module.  If you would like to get
> some different photos, please let me know and I will see what I can do.  Any
> thoughts or ideas would be greatly appreciated!  Thanks!
> 
> 
> 
>-Randal   (at CubeCentral)
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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[time-nuts] Help Identifying this surplus Timing Module

[CubeCentral]

Hello All!

 

I would like to enlist your help in identifying this "surplus Timing
Module":  https://imgur.com/a/Psw8gP7 

 

All the hints I've been given are:

- Purchased about a decade ago

- Might use a Motorola DSP as the processor

 

A quick google search lead me to a possible description:

"High speed, hitless, ultra low jitter timing module for OC-N line
interfaces:  The TF Systems / ATiMe-LC is a timing reference source for OC-N
and STM-N interfaces. It complements TeraSync's central timing modules to
provide a complete and redundant timing solution at the system level."

 

...but I'm unsure if that is 100% the same module.  If you would like to get
some different photos, please let me know and I will see what I can do.  Any
thoughts or ideas would be greatly appreciated!  Thanks!

 

-Randal   (at CubeCentral)

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Re: [time-nuts] Help improving impedance measurement by having a better clock

[Bob kb8tq]

Hi

I believe we are talking about material impedances here rather than electrical 
impedance. One of the 
weird things about this is that frequency (as in frequency accuracy) *can* be a 
contributor to the resultant
error. Thus my original question about just what the concern actually is…..

Bob

> On Apr 8, 2018, at 4:52 PM, Brooke Clarke  wrote:
> 
> Hi Daniel:
> 
> If you're concerned with accuracy of impedance measurements you might want to 
> spent a lot of time studying "The Impedance Measurement Handbook", it's the 
> bible for this.  The way the measurement is made has a huge impact on the 
> accuracy.  For example using a vector network analyzer to measure an 
> impedance that's not near 50 Ohms causes poor results.
> http://prc68.com/I/Z.shtml#KeyDocs
> For frequencies low enough to use 4 Terminal Pair, that's the way to go.
> http://www.prc68.com/I/HP4274_4275_LCR.shtml#MeasMtd
> 
> -- 
> Have Fun,
> 
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> 
>  Original Message 
>> I´m a long time time-nuts lurker (I posted here just a dozen times). I make
>> a few impedance measurement systems for material analysis (i´m a single man
>> shop doing custom hardware for clients). Usually they´re based around a
>> STM32F4 / F7 microprocessor: DAC generates sine signal (1-400KHz), ADCs
>> measure them back, a few calculations later we have modulus / phase. I
>> always used internal ADCs and DACs (12 bits each).
>> 
>> I now want to use external ADCs and DACs with more bits to push the limits,
>> but i´m afraid that the poor performance of the STM32 PLL that drives the
>> clock will get in the way, so I plan to drive the "load" of both DAC and
>> ADCs from an external signal derived from a TCXO using a clock divider.
>> 
>> To get some sense of how much things are improving (or not) I need to
>> somehow measure these clocks and get a meaningfull measurement about how
>> good (or bad) they are.
>> 
>> The tools I have are a Hameg HM8123 with a 10MHz OCXO I shoehorned inside
>> and a Picotest U6200A with original OCXO. I can log period information from
>> both using serial/USB port. I can make a histogram of the data. I don´t
>> have any better idea about what to do and would like to hear from you :)
>> 
>> Daniel
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
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>> 
> 
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Re: [time-nuts] Help improving impedance measurement by having a better clock

[Brooke Clarke]

Hi Daniel:

If you're concerned with accuracy of impedance measurements you might want to spent a lot of time studying "The 
Impedance Measurement Handbook", it's the bible for this.  The way the measurement is made has a huge impact on the 
accuracy.  For example using a vector network analyzer to measure an impedance that's not near 50 Ohms causes poor results.

http://prc68.com/I/Z.shtml#KeyDocs
For frequencies low enough to use 4 Terminal Pair, that's the way to go.
http://www.prc68.com/I/HP4274_4275_LCR.shtml#MeasMtd

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

 Original Message 

I´m a long time time-nuts lurker (I posted here just a dozen times). I make
a few impedance measurement systems for material analysis (i´m a single man
shop doing custom hardware for clients). Usually they´re based around a
STM32F4 / F7 microprocessor: DAC generates sine signal (1-400KHz), ADCs
measure them back, a few calculations later we have modulus / phase. I
always used internal ADCs and DACs (12 bits each).

I now want to use external ADCs and DACs with more bits to push the limits,
but i´m afraid that the poor performance of the STM32 PLL that drives the
clock will get in the way, so I plan to drive the "load" of both DAC and
ADCs from an external signal derived from a TCXO using a clock divider.

To get some sense of how much things are improving (or not) I need to
somehow measure these clocks and get a meaningfull measurement about how
good (or bad) they are.

The tools I have are a Hameg HM8123 with a 10MHz OCXO I shoehorned inside
and a Picotest U6200A with original OCXO. I can log period information from
both using serial/USB port. I can make a histogram of the data. I don´t
have any better idea about what to do and would like to hear from you :)

Daniel
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Re: [time-nuts] Help improving impedance measurement by having a better clock

[Attila Kinali]

On Sat, 7 Apr 2018 22:54:42 -0300
Daniel Mendes  wrote:

> I´m a long time time-nuts lurker (I posted here just a dozen times). I make
> a few impedance measurement systems for material analysis (i´m a single man
> shop doing custom hardware for clients). Usually they´re based around a
> STM32F4 / F7 microprocessor: DAC generates sine signal (1-400KHz), ADCs
> measure them back, a few calculations later we have modulus / phase. I
> always used internal ADCs and DACs (12 bits each).

The STM32's are known for their poorly performing ADCs and DACs,
even using an external one with the same bit width will increase
your performance. That said, what is your actual sample rate?
I would guess, if you use the timer unit to generate the pulses,
your jitter would be less than 10ps rms, probably even less than 1ps rms.
10ps rms limits your resolution to something like 14-15bit @500kHz,
1ps rms should be around 18bits, if I'm not mistaken. 

To measure the performance, I would just build the device and feed it
with an appropriate sine wave. Then analyze the SNR and spurs of the
sampled signal.

Attila Kinali

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Help improving impedance measurement by having a better clock

[Bob kb8tq]

Hi

I’m not at all sure that the clocks will really get into the measurements. The 
PLL does 
have jitter, but it has zero frequency error. 

One way to get around the whole issue is to use an outboard device with its own 
clock. 
400 KHz is a bit high for the integrated audio ADC / DAC parts. Drop down a bit 
and 
they will do quite well. Interface with an I2S port and away you go.

That said, are you concerned about frequency error or jitter? If it’s frequency 
error, you 
can get that pretty well a number of ways. The gotcha is an accurate reference. 
A GPSDO
is by far the cheapest way to solve that problem.

If you are concerned about jitter, the next question is: over what range? It is 
reasonable 
to guess that the PLL follows the input to a pretty good degree for long time 
periods. At
some point the PLL loop filter allows it to move around a bit. The issue here 
is that the loop 
filter likely is in the audio range. You are after jitter at time periods << 1 
second. That gets
a bit gear specific. You also are after numbers in the nanosecond (or sub 
nanosecond) range.
That increases the complexity. 

So - what are you after? 

Bob

> On Apr 7, 2018, at 9:54 PM, Daniel Mendes  wrote:
> 
> I´m a long time time-nuts lurker (I posted here just a dozen times). I make
> a few impedance measurement systems for material analysis (i´m a single man
> shop doing custom hardware for clients). Usually they´re based around a
> STM32F4 / F7 microprocessor: DAC generates sine signal (1-400KHz), ADCs
> measure them back, a few calculations later we have modulus / phase. I
> always used internal ADCs and DACs (12 bits each).
> 
> I now want to use external ADCs and DACs with more bits to push the limits,
> but i´m afraid that the poor performance of the STM32 PLL that drives the
> clock will get in the way, so I plan to drive the "load" of both DAC and
> ADCs from an external signal derived from a TCXO using a clock divider.
> 
> To get some sense of how much things are improving (or not) I need to
> somehow measure these clocks and get a meaningfull measurement about how
> good (or bad) they are.
> 
> The tools I have are a Hameg HM8123 with a 10MHz OCXO I shoehorned inside
> and a Picotest U6200A with original OCXO. I can log period information from
> both using serial/USB port. I can make a histogram of the data. I don´t
> have any better idea about what to do and would like to hear from you :)
> 
> Daniel
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[time-nuts] Help improving impedance measurement by having a better clock

[Daniel Mendes]

I´m a long time time-nuts lurker (I posted here just a dozen times). I make
a few impedance measurement systems for material analysis (i´m a single man
shop doing custom hardware for clients). Usually they´re based around a
STM32F4 / F7 microprocessor: DAC generates sine signal (1-400KHz), ADCs
measure them back, a few calculations later we have modulus / phase. I
always used internal ADCs and DACs (12 bits each).

I now want to use external ADCs and DACs with more bits to push the limits,
but i´m afraid that the poor performance of the STM32 PLL that drives the
clock will get in the way, so I plan to drive the "load" of both DAC and
ADCs from an external signal derived from a TCXO using a clock divider.

To get some sense of how much things are improving (or not) I need to
somehow measure these clocks and get a meaningfull measurement about how
good (or bad) they are.

The tools I have are a Hameg HM8123 with a 10MHz OCXO I shoehorned inside
and a Picotest U6200A with original OCXO. I can log period information from
both using serial/USB port. I can make a histogram of the data. I don´t
have any better idea about what to do and would like to hear from you :)

Daniel
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Re: [time-nuts] help

[Adrian Godwin]

Since you have an impulse clock system, you could use that to fire the bell
- you could modify a slave clock or use one of these :

http://www.ebay.co.uk/itm/111982558390

or possibly this one :

http://www.ebay.co.uk/itm/291730808914

The first seems rather expensive to me, I've more commonly seen them at
more like the second price. You can probably find one nearer to you.

You still then have the problem that you want to drive the impulse from an
accurate time source. There are impulse drivers that operate from a cheap
crystal available on ebay. I don't think we want to talk about those here.

A nicer solution would be to transform the 1pps signal from a gps receiver
into a suitable pulse : again, this is easy to do with a microcontroller
and a small amount of electronics, but it seems like a useful idea. Perhaps
worth working out properly and publishing.

I have in the past run a slave clock from an RS232 port : it needs a small
circuit to generate the current pulse (powered by the RS232 port itself)
and operated by a small script program on a computer, so locked to NTP.
However, it needs a computer (preferably Unix) running 24/7.




On Mon, May 2, 2016 at 7:11 PM, Mark Sims  wrote:

> If you want to get fancy you could modify Lady Heather to do the deed.
> Heather has a "singing clock" mode and a cuckoo/chime clock mode for
> playing sound files at various times.  It also has routines for controlling
> the serial port DTR and RTS lines (currently used for PWMing a fan if
> temperature control mode is enabled).   You could add some code to the
> program to pulse the DTR or RTS line... these can easily drive a solid
> state relay.
>
>
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Re: [time-nuts] help

[Tom Van Baak]

It turns out OP (Bill Baker) is using a very nice GMR1000 GPS time standard:

http://www.masterclock.com/products/master-clocks/gmr1000/

So that's why he was asking about an off-the-shelf device to turn SMPTE into an 
hourly switch for his fog bell.

Since the GMR1000 also has a network connection, the proposed Raspberry Pi 
solutions will work. In addition, the GMR1000 has a serial port that will 
output NMEA (GPZDA), so even a simple PIC or Arduino solution is possible.

Given a choice between RS232 + Arduino on the one hand and LAN + Raspberry Pi + 
Linux + NTP on the other, I'd pick Arduino. But I know people that would throw 
Linux at this; everyone has their favorite hammer. In fact, I bet Walter 
Shawlee could design a simple TTL shift-register circuit that would parse the 
RS232 GPZDA bitstream and drive the fog bell on the hour. And a hundred years 
from now his TTL board and the bell would be the only parts still working.

/tvb

For more information read GMR1000.pdf and GMR+Series+User+Manual.pdf from the 
site above.


> - Original Message - 
> From: "Bill Baker via time-nuts" <time-nuts@febo.com>
> Sent: Sunday, May 01, 2016 12:26 PM
> Subject: [time-nuts] help
>
> My problem:  I'd like some kind of off-the-shelf device that can take the 
> time code
> and switch on or impulse another circuit-- specifically  I'd like to trigger 
> a 180 year-old
> fog bell (I'm a lighthouse nut as well, www.henryisland.com) on the hour and 
> maybe
> be able to impulse my minute school clocks.  I'm not at this group's 
> technical level,
> so it's got to be pretty easy to program. So I need a box that I can program 
> with
> SMPTE time in and a timed switch impulse out.  Any ideas?
>Many thanks,
>W1BKR

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Re: [time-nuts] help

[albertson . chris]

You don't care about the lag in cron. You care about the variation of the lag.  
 

Then again. The main cause of lag in a fog horn is the speed of sound  

You set cron to fire at T minus the average lag time. 

> On May 2, 2016, at 2:36 PM, Nick Sayer via time-nuts  
> wrote:
> 
> 
>> On May 2, 2016, at 9:51 AM, jimlux  wrote:
>> 
>> 
>> The real question is whether "cron" is timely enough.  No matter, just write 
>> a script (or python) that reads time in a loop (and you can put a sleep in 
>> there) and pulses the GPIO when needed.
> 
> A Raspberry Pi with nothing else on its plate will have a cron-to-shell 
> script latency easily under 100 ms, possibly under 10.
> 
> If it were me and I were triggering a relay for some sort of external 
> circuit, I’d probably be happy it was on the right side of 500 ms. If I cared 
> more than that, then step 1 would be to do as others have suggested and come 
> up with a microcontroller + GPS solution instead of NTP + cron. Ironically, 
> that’d be around the same price (albeit more engineering work).
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Re: [time-nuts] help

[Martin Burnicki]

Am 3. Mai 2016 18:06:49 MESZ, schrieb Hendrik Dietrich :
>
>Picking up the time from a DAYTIME Server is easier to implement than 
>NTP, these respond just with a string containing date and time.

If you don't want to run NTP then eventually you sould use the "time" protocol 
rather than daytime . 

"time" returns UTC,  but IIRC then daytime can even return some local time,  
and the string format may depend on / vary wit the server you are contacting. 
It's more for human interaction. 

Martin 

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[time-nuts] help

[Hendrik Dietrich]

Hi,

about getting time from the Internet to a clockwork:
Have a look at the ESP8266, which you can get from china for as low as 
4€ in the embodiment of a AMICA board:


Its a controller with some GPIOs and WLAN enabled, freely programmable 
(Either with the ARDUINO IDE, or with a LUA or BASIC Firmware.)
Picking up the time from a DAYTIME Server is easier to implement than 
NTP, these respond just with a string containing date and time.
At ~100 mA fully on its a good competitor to the Raspies regarding 
current consumption.


BR
Hendrik

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[time-nuts] help

[Mark Sims]

If you want to get fancy you could modify Lady Heather to do the deed.  Heather 
has a "singing clock" mode and a cuckoo/chime clock mode for playing sound 
files at various times.  It also has routines for controlling the serial port 
DTR and RTS lines (currently used for PWMing a fan if temperature control mode 
is enabled).   You could add some code to the program to pulse the DTR or RTS 
line... these can easily drive a solid state relay.

  
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Re: [time-nuts] help

[Bob Camp]

Hi

A cheap GPS module and any of the nearly infinite number of sub $20 “demo 
boards” would make 
short work of looking at the pps, the time string out of the GPS and figuring 
out when it’s the top of the 
hour. I doubt it’s over 200 lines of code. I’m sure *somebody* will pop up with 
an example well below
that. No need for an OS. No need for anything complex. There’s sure to be 
enough room even on a $2 board
to include added stuff like real time clock driver and correcting the “local 
time” against GPS. 

Bob

> On May 2, 2016, at 5:36 PM, Nick Sayer via time-nuts  
> wrote:
> 
> 
>> On May 2, 2016, at 9:51 AM, jimlux  wrote:
>> 
>> 
>> The real question is whether "cron" is timely enough.  No matter, just write 
>> a script (or python) that reads time in a loop (and you can put a sleep in 
>> there) and pulses the GPIO when needed.
>> 
> 
> A Raspberry Pi with nothing else on its plate will have a cron-to-shell 
> script latency easily under 100 ms, possibly under 10.
> 
> If it were me and I were triggering a relay for some sort of external 
> circuit, I’d probably be happy it was on the right side of 500 ms. If I cared 
> more than that, then step 1 would be to do as others have suggested and come 
> up with a microcontroller + GPS solution instead of NTP + cron. Ironically, 
> that’d be around the same price (albeit more engineering work).
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Re: [time-nuts] help

[Nick Sayer via time-nuts]

> On May 2, 2016, at 9:51 AM, jimlux  wrote:
> 
> 
> The real question is whether "cron" is timely enough.  No matter, just write 
> a script (or python) that reads time in a loop (and you can put a sleep in 
> there) and pulses the GPIO when needed.
> 

A Raspberry Pi with nothing else on its plate will have a cron-to-shell script 
latency easily under 100 ms, possibly under 10.

If it were me and I were triggering a relay for some sort of external circuit, 
I’d probably be happy it was on the right side of 500 ms. If I cared more than 
that, then step 1 would be to do as others have suggested and come up with a 
microcontroller + GPS solution instead of NTP + cron. Ironically, that’d be 
around the same price (albeit more engineering work).
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Re: [time-nuts] help

[Adrian Godwin]

Here's a possible solution. It's ethernet-connected and will switch a 10A
output. It's made for UK use but would probably be fine if you have a 220V
supply. It doesn't say whether it tracks NTP, but looking at the specs i'd
suggest it's linux inside and can do that.

http://www.audon.co.uk/webcontrol/EZ-21g.html


On Mon, May 2, 2016 at 7:21 PM, Adrian Godwin  wrote:

> They're a LED and some current limiting. Some are specced as low as 3V and
> 10mA but they're optimised for 12-24. I'd definitely use a transistor and
> at least 5V, especially from something like a Pi or Teensy, which have 3v3
> logic levels.
>
> My reading is that Bill doesn't want to mess around with micros and
> electronics, though. He wants an off-the-shelf timeswitch that - for
> perfectly understandable reasons of engineering pedantry - is always
> correct.
>
> On Mon, May 2, 2016 at 5:56 PM, jimlux  wrote:
>
>> On 5/2/16 8:24 AM, Nick Sayer via time-nuts wrote:
>>
>>> To flesh this out a bit more, on a Raspberry Pi, it would be easy to
>>> make a cron job that would pulse a GPIO pin high. They really *want* you to
>>> use Python (thus the name), but this is easy to do in just a shell script.
>>> First, do this to set things up:
>>>
>>> #! /bin/sh
>>>
>>> GPIO_PIN=9 # pick whatever one you like
>>>
>>> echo $GPIO_PIN > /sys/class/gpio/export
>>> echo out > /sys/class/gpio/gpio${GPIO_PIN}/direction
>>> echo 0 > /sys/class/gpio/gpio${GPIO_PIN}/value
>>>
>>> Next, run this script out of cron:
>>>
>>> #! /bin/sh
>>>
>>> GPIO_PIN=9
>>> echo 1 > /sys/class/gpio/gpio${GPIO_PIN}/value
>>> sleep 1
>>> echo 0 > /sys/class/gpio/gpio${GPIO_PIN}/value
>>>
>>> That will make a positive going pulse with the leading edge synchronized
>>> to cron (for sufficiently vague definitions of “synchronized”).
>>>
>>> As for the hardware side, take the GPIO pin and connect a 10k resistor
>>> between it and the base of a 2N4401 transistor. Connect the emitter to
>>> ground and the collector is a classic “open collector” switching output.
>>> Think of it like a switch connection to ground. When it’s on, there is a
>>> low impedance path to ground. When it’s off, it’s high impedance. You can
>>> use it to work a relay (be sure to add a flyback diode across the relay
>>> coil) or directly to switch any load that doesn’t exceed the abilities of
>>> the transistor.
>>>
>>> If you want to be a little safer, you can use an opto-isolator instead.
>>> Connect the GPIO pin to a 150 Ω resistor and then to the anode of the LED
>>> in an optoisolator. Connect the cathode to ground. The optoisolator itself
>>> can be either a phototransistor type or a driver triac type (the latter
>>> would be used to drive a power triac to switch AC loads on and off).
>>>
>>>
>>>
>>
>> SSR data sheet at mouser (they are <$20)
>> http://www.mouser.com/ds/2/307/g3na_ds_e_11_1_csm165-892371.pdf
>>
>> myriad varieties of inputs and outputs, whether it has an indicator (nice
>> for testing), whether it's a zero voltage switch.
>>
>> BUT.. it kind of looks like it wants to see 4V to turn on for sure. Maybe
>> your 5V USB powered widget puts out that on a GPIO pin, maybe it doesn't.
>> I've had very mixed luck with driving SSRs directly from logic (because the
>> real threshold voltage and the real logic output voltage vary with
>> temperature, for instance).
>>
>> I'd use the extra transistor as an open collector and a 12V wall wart or
>> similar to provide the current for the SSR input.
>>
>>
>>
>>
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>>
>
>
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Re: [time-nuts] help

[Adrian Godwin]

They're a LED and some current limiting. Some are specced as low as 3V and
10mA but they're optimised for 12-24. I'd definitely use a transistor and
at least 5V, especially from something like a Pi or Teensy, which have 3v3
logic levels.

My reading is that Bill doesn't want to mess around with micros and
electronics, though. He wants an off-the-shelf timeswitch that - for
perfectly understandable reasons of engineering pedantry - is always
correct.

On Mon, May 2, 2016 at 5:56 PM, jimlux  wrote:

> On 5/2/16 8:24 AM, Nick Sayer via time-nuts wrote:
>
>> To flesh this out a bit more, on a Raspberry Pi, it would be easy to make
>> a cron job that would pulse a GPIO pin high. They really *want* you to use
>> Python (thus the name), but this is easy to do in just a shell script.
>> First, do this to set things up:
>>
>> #! /bin/sh
>>
>> GPIO_PIN=9 # pick whatever one you like
>>
>> echo $GPIO_PIN > /sys/class/gpio/export
>> echo out > /sys/class/gpio/gpio${GPIO_PIN}/direction
>> echo 0 > /sys/class/gpio/gpio${GPIO_PIN}/value
>>
>> Next, run this script out of cron:
>>
>> #! /bin/sh
>>
>> GPIO_PIN=9
>> echo 1 > /sys/class/gpio/gpio${GPIO_PIN}/value
>> sleep 1
>> echo 0 > /sys/class/gpio/gpio${GPIO_PIN}/value
>>
>> That will make a positive going pulse with the leading edge synchronized
>> to cron (for sufficiently vague definitions of “synchronized”).
>>
>> As for the hardware side, take the GPIO pin and connect a 10k resistor
>> between it and the base of a 2N4401 transistor. Connect the emitter to
>> ground and the collector is a classic “open collector” switching output.
>> Think of it like a switch connection to ground. When it’s on, there is a
>> low impedance path to ground. When it’s off, it’s high impedance. You can
>> use it to work a relay (be sure to add a flyback diode across the relay
>> coil) or directly to switch any load that doesn’t exceed the abilities of
>> the transistor.
>>
>> If you want to be a little safer, you can use an opto-isolator instead.
>> Connect the GPIO pin to a 150 Ω resistor and then to the anode of the LED
>> in an optoisolator. Connect the cathode to ground. The optoisolator itself
>> can be either a phototransistor type or a driver triac type (the latter
>> would be used to drive a power triac to switch AC loads on and off).
>>
>>
>>
>
> SSR data sheet at mouser (they are <$20)
> http://www.mouser.com/ds/2/307/g3na_ds_e_11_1_csm165-892371.pdf
>
> myriad varieties of inputs and outputs, whether it has an indicator (nice
> for testing), whether it's a zero voltage switch.
>
> BUT.. it kind of looks like it wants to see 4V to turn on for sure. Maybe
> your 5V USB powered widget puts out that on a GPIO pin, maybe it doesn't.
> I've had very mixed luck with driving SSRs directly from logic (because the
> real threshold voltage and the real logic output voltage vary with
> temperature, for instance).
>
> I'd use the extra transistor as an open collector and a 12V wall wart or
> similar to provide the current for the SSR input.
>
>
>
>
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Re: [time-nuts] help

[jimlux]

On 5/2/16 8:24 AM, Nick Sayer via time-nuts wrote:

To flesh this out a bit more, on a Raspberry Pi, it would be easy to make a 
cron job that would pulse a GPIO pin high. They really *want* you to use Python 
(thus the name), but this is easy to do in just a shell script. First, do this 
to set things up:

#! /bin/sh

GPIO_PIN=9 # pick whatever one you like

echo $GPIO_PIN > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio${GPIO_PIN}/direction
echo 0 > /sys/class/gpio/gpio${GPIO_PIN}/value

Next, run this script out of cron:

#! /bin/sh

GPIO_PIN=9
echo 1 > /sys/class/gpio/gpio${GPIO_PIN}/value
sleep 1
echo 0 > /sys/class/gpio/gpio${GPIO_PIN}/value

That will make a positive going pulse with the leading edge synchronized to 
cron (for sufficiently vague definitions of “synchronized”).

As for the hardware side, take the GPIO pin and connect a 10k resistor between 
it and the base of a 2N4401 transistor. Connect the emitter to ground and the 
collector is a classic “open collector” switching output. Think of it like a 
switch connection to ground. When it’s on, there is a low impedance path to 
ground. When it’s off, it’s high impedance. You can use it to work a relay (be 
sure to add a flyback diode across the relay coil) or directly to switch any 
load that doesn’t exceed the abilities of the transistor.

If you want to be a little safer, you can use an opto-isolator instead. Connect 
the GPIO pin to a 150 Ω resistor and then to the anode of the LED in an 
optoisolator. Connect the cathode to ground. The optoisolator itself can be 
either a phototransistor type or a driver triac type (the latter would be used 
to drive a power triac to switch AC loads on and off).





SSR data sheet at mouser (they are <$20)
http://www.mouser.com/ds/2/307/g3na_ds_e_11_1_csm165-892371.pdf

myriad varieties of inputs and outputs, whether it has an indicator 
(nice for testing), whether it's a zero voltage switch.


BUT.. it kind of looks like it wants to see 4V to turn on for sure. 
Maybe your 5V USB powered widget puts out that on a GPIO pin, maybe it 
doesn't. I've had very mixed luck with driving SSRs directly from logic 
(because the real threshold voltage and the real logic output voltage 
vary with temperature, for instance).


I'd use the extra transistor as an open collector and a 12V wall wart or 
similar to provide the current for the SSR input.




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Re: [time-nuts] help

[jimlux]

On 5/2/16 8:24 AM, Nick Sayer via time-nuts wrote:

To flesh this out a bit more, on a Raspberry Pi, it would be easy to make a 
cron job that would pulse a GPIO pin high. They really *want* you to use Python 
(thus the name), but this is easy to do in just a shell script. First, do this 
to set things up:

#! /bin/sh

GPIO_PIN=9 # pick whatever one you like

echo $GPIO_PIN > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio${GPIO_PIN}/direction
echo 0 > /sys/class/gpio/gpio${GPIO_PIN}/value

Next, run this script out of cron:

#! /bin/sh

GPIO_PIN=9
echo 1 > /sys/class/gpio/gpio${GPIO_PIN}/value
sleep 1
echo 0 > /sys/class/gpio/gpio${GPIO_PIN}/value

That will make a positive going pulse with the leading edge synchronized to 
cron (for sufficiently vague definitions of “synchronized”).

As for the hardware side, take the GPIO pin and connect a 10k resistor between 
it and the base of a 2N4401 transistor. Connect the emitter to ground and the 
collector is a classic “open collector” switching output. Think of it like a 
switch connection to ground. When it’s on, there is a low impedance path to 
ground. When it’s off, it’s high impedance. You can use it to work a relay (be 
sure to add a flyback diode across the relay coil) or directly to switch any 
load that doesn’t exceed the abilities of the transistor.

If you want to be a little safer, you can use an opto-isolator instead. Connect 
the GPIO pin to a 150 Ω resistor and then to the anode of the LED in an 
optoisolator. Connect the cathode to ground. The optoisolator itself can be 
either a phototransistor type or a driver triac type (the latter would be used 
to drive a power triac to switch AC loads on and off).




Or just buy a DC controlled solid state relay..  The NPN open collector 
current booster might be nice still, but the SSR takes care of all the 
galvanic isolation, etc.



The real question is whether "cron" is timely enough.  No matter, just 
write a script (or python) that reads time in a loop (and you can put a 
sleep in there) and pulses the GPIO when needed.






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Re: [time-nuts] help

[Nick Sayer via time-nuts]

To flesh this out a bit more, on a Raspberry Pi, it would be easy to make a 
cron job that would pulse a GPIO pin high. They really *want* you to use Python 
(thus the name), but this is easy to do in just a shell script. First, do this 
to set things up:

#! /bin/sh

GPIO_PIN=9 # pick whatever one you like

echo $GPIO_PIN > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio${GPIO_PIN}/direction
echo 0 > /sys/class/gpio/gpio${GPIO_PIN}/value

Next, run this script out of cron:

#! /bin/sh

GPIO_PIN=9
echo 1 > /sys/class/gpio/gpio${GPIO_PIN}/value
sleep 1
echo 0 > /sys/class/gpio/gpio${GPIO_PIN}/value

That will make a positive going pulse with the leading edge synchronized to 
cron (for sufficiently vague definitions of “synchronized”).

As for the hardware side, take the GPIO pin and connect a 10k resistor between 
it and the base of a 2N4401 transistor. Connect the emitter to ground and the 
collector is a classic “open collector” switching output. Think of it like a 
switch connection to ground. When it’s on, there is a low impedance path to 
ground. When it’s off, it’s high impedance. You can use it to work a relay (be 
sure to add a flyback diode across the relay coil) or directly to switch any 
load that doesn’t exceed the abilities of the transistor.

If you want to be a little safer, you can use an opto-isolator instead. Connect 
the GPIO pin to a 150 Ω resistor and then to the anode of the LED in an 
optoisolator. Connect the cathode to ground. The optoisolator itself can be 
either a phototransistor type or a driver triac type (the latter would be used 
to drive a power triac to switch AC loads on and off).


> On May 1, 2016, at 6:30 PM, Chris Albertson  wrote:
> 
>> But are you sure you want SMPTE... Do you have a source already?
>> 
>> 
> You don't need GPS or SMPTE if you have an Internet connection.  The
> computer can use a set of NTP servers from the "pool" to get time.  The
> result is good enough that the seed of sound delay resulting from your
> random distance to the bell will be the largest source of error.
> 
> If you convert timing errors to distance at the speed of sound.   You would
> need the GPS only if you car about bell to ear distances of about one foot,
> give or take
> 
> So for this use case the OP does not need a GPS or even a SMTPE connection
> just a WiFi link to the internet would be more than enough for controlling
> a horn blast from a light house
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] help

[jimlux]

On 5/1/16 6:30 PM, Chris Albertson wrote:

But are you sure you want SMPTE... Do you have a source already?



You don't need GPS or SMPTE if you have an Internet connection.  The
computer can use a set of NTP servers from the "pool" to get time.  The
result is good enough that the seed of sound delay resulting from your
random distance to the bell will be the largest source of error.

If you convert timing errors to distance at the speed of sound.   You would
need the GPS only if you car about bell to ear distances of about one foot,
give or take

So for this use case the OP does not need a GPS or even a SMTPE connection
just a WiFi link to the internet would be more than enough for controlling
a horn blast from a light house





However, depending on how much work you want to do, it's easier to 
decode the serial stream from a GPS receiver or SMPTE and close a relay, 
than it is to set up an internet connection, make sure it's not 
vulnerable, etc.etc.etc.


If you already have a PC with a connection, sure, it's straightforward, 
but if you're starting from scratch, the work to get the whole internet 
software stack up and running particularly on a small cheap board is 
substantial.


If you already have a Arduino/Beaglebone/Rpi set up, and safely 
connected to the internet, then you could just copy that; but if you've 
not done it before, it takes a while.



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Re: [time-nuts] help

[Mike Cook]

> Le 2 mai 2016 à 03:14, Chris Albertson  a écrit :
> 
> On Sun, May 1, 2016 at 12:26 PM, Bill Baker via time-nuts <
> time-nuts@febo.com> wrote:
> 
>> My problem:  I'd like some kind of off-the-shelf device that can take the
>> time code and switch on or impulse another circuit-- specifically  I'd like
>> to trigger a 180 year-old fog bell (I'm a lighthouse nut as well,
>> www.henryisland.com) on the hour and maybe be able to impulse my minute
>> school clocks.  I'm not at this group's technical level, so it's got to be
>> pretty easy to program. So I need a box that I can program with SMPTE time
>> in and a timed switch impulse out.  Any ideas?
> 
> 
> I assume you only need to be accurate to within about 1/10th of a second or
> so.  Any general purpose computer like and old PC can do this but today
> you'd go with a Raspberry Pi 2 or some other single board computer.   The
> first step is to keep the computer's internal clock in sync with your time
> signal (NTP can do that and NTP will likely already be installed on the
> computer)  then if the computer is running a Unix-like OS (such as Linux,
> BSD or Mac OS X) there is a table you can set up that will run various apps
> at certain scheduled times.   You'd simply set s cron tab entry to blow the
> horn on every hour every hour.  

cron isn’t good enough for < 1s accuracy timing even with a GPS steered clock.
It only wakes up every minute and the time used scanning all crontab tables to 
see what needs to be run in that minute and scheduling those means that you 
rarely get a job executed in < 1s of the desired time. 

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Re: [time-nuts] help

[Chris Albertson]

> But are you sure you want SMPTE... Do you have a source already?
>
>
You don't need GPS or SMPTE if you have an Internet connection.  The
computer can use a set of NTP servers from the "pool" to get time.  The
result is good enough that the seed of sound delay resulting from your
random distance to the bell will be the largest source of error.

If you convert timing errors to distance at the speed of sound.   You would
need the GPS only if you car about bell to ear distances of about one foot,
give or take

So for this use case the OP does not need a GPS or even a SMTPE connection
just a WiFi link to the internet would be more than enough for controlling
a horn blast from a light house


-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] help

[Chris Albertson]

On Sun, May 1, 2016 at 12:26 PM, Bill Baker via time-nuts <
time-nuts@febo.com> wrote:

> My problem:  I'd like some kind of off-the-shelf device that can take the
> time code and switch on or impulse another circuit-- specifically  I'd like
> to trigger a 180 year-old fog bell (I'm a lighthouse nut as well,
> www.henryisland.com) on the hour and maybe be able to impulse my minute
> school clocks.  I'm not at this group's technical level, so it's got to be
> pretty easy to program. So I need a box that I can program with SMPTE time
> in and a timed switch impulse out.  Any ideas?


I assume you only need to be accurate to within about 1/10th of a second or
so.  Any general purpose computer like and old PC can do this but today
you'd go with a Raspberry Pi 2 or some other single board computer.   The
first step is to keep the computer's internal clock in sync with your time
signal (NTP can do that and NTP will likely already be installed on the
computer)  then if the computer is running a Unix-like OS (such as Linux,
BSD or Mac OS X) there is a table you can set up that will run various apps
at certain scheduled times.   You'd simply set s cron tab entry to blow the
horn on every hour every hour.   Not much software to write as this kind of
stuff (syncing to an external clock and doing things on a schedule) is
built in to the OS.

OK if you need to be much more accurate it gets harder but really this is a
audio alarm and the speed of sound is very slow such that the delay you'd
experience from sending 100 feet from the fog bell is longer than the delay
introduced by the software

So yjr only thing you need is to write software that does just one thing,
ring the bell then quit and let "crond" call it based on entries from the
table.

I see suggestion to use an Arduino or the like and program it.  That could
work too but if the little computer is powerful enough to run a unix-lil OS
you save some effort because they already come with built-in utilities to
do things on a schulue and to stay sync'd with an external clock signal.
-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] help

[jimlux]

On 5/1/16 1:26 PM, jimlux wrote:

On 5/1/16 12:26 PM, Bill Baker via time-nuts wrote:

My problem:  I'd like some kind of off-the-shelf device that can take
the time code and switch on or impulse another circuit-- specifically
I'd like to trigger a 180 year-old fog bell (I'm a lighthouse nut as
well, www.henryisland.com) on the hour and maybe be able to impulse my
minute school clocks.  I'm not at this group's technical level, so
it's got to be pretty easy to program. So I need a box that I can
program with SMPTE time in and a timed switch impulse out.  Any ideas?
Many thanks,
W1BKR


An Arduino or Teensy (http://www.pjrc.com) are both trivially easy to
program and have easy interfaces (With a large number of off the shelf
interface widgets like relays, optoisolators, etc.).  There's probably
off the shelf code and hardware interfaces for decoding your SMPTE or
other time codes.



In fact
http://forum.arduino.cc/index.php?topic=8237.0

https://hackaday.io/project/7694-arduino-timecode-smpte-ltc-reader-generator-shield/log/27289-stripped-down-ltc-reader-code-for-arduino

references someone decoding SMPTE from an audio signal.



But are you sure you want SMPTE... Do you have a source already?


Seems to me you'd want something like a GPS receiver.. equally easy. 
I've got code the reads a Garmin GPS-18 on a teensy somewhere around, 
and I'm sure others have stuff for basically any GPS receiver made.


Lately, i've just been logging 1pps from various sources using the teensy.

After all, don't you want your fog bell to be accurate to fractions of a 
microsecond, because otherwise you're not really a time-nut .







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Re: [time-nuts] help

[jimlux]

On 5/1/16 12:26 PM, Bill Baker via time-nuts wrote:

My problem:  I'd like some kind of off-the-shelf device that can take the time 
code and switch on or impulse another circuit-- specifically  I'd like to 
trigger a 180 year-old fog bell (I'm a lighthouse nut as well, 
www.henryisland.com) on the hour and maybe be able to impulse my minute school 
clocks.  I'm not at this group's technical level, so it's got to be pretty easy 
to program. So I need a box that I can program with SMPTE time in and a timed 
switch impulse out.  Any ideas?
Many thanks,
W1BKR


An Arduino or Teensy (http://www.pjrc.com) are both trivially easy to 
program and have easy interfaces (With a large number of off the shelf 
interface widgets like relays, optoisolators, etc.).  There's probably 
off the shelf code and hardware interfaces for decoding your SMPTE or 
other time codes.


The coding would be simple - the widget's not doing anything else, so 
there's nothing wrong with a structure like


void loop(){
if (msgavailable) {
get message
decode message
if right message{
digitalWrite(relaypin,HIGH)
sleep (10)
digitalWrite(relaypin,LOW)
}
}
}



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[time-nuts] help

[Bill Baker via time-nuts]

My problem:  I'd like some kind of off-the-shelf device that can take the time 
code and switch on or impulse another circuit-- specifically  I'd like to 
trigger a 180 year-old fog bell (I'm a lighthouse nut as well, 
www.henryisland.com) on the hour and maybe be able to impulse my minute school 
clocks.  I'm not at this group's technical level, so it's got to be pretty easy 
to program. So I need a box that I can program with SMPTE time in and a timed 
switch impulse out.  Any ideas?
Many thanks,
W1BKR
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Re: [time-nuts] Help with my ADEV measurement setup

[Dan Watson]

Oddly enough I do have a PPS output from the TCXO I was measuring. It's on
a little board I made and there is a PicDiv right on it. I'll have to play
around with that.

I did notice the aliasing issue trying to measure a 12MHz crystal. It
appeared to have incredible stability and accuracy for a plain old XO...
Also it has a frequency offset of over 1kHz, and I noticed that I had to
manually type in the correct initial frequency during setup to have
meaningful data in the frequency difference view. i.e, 12001053 instead of
12E6. But of course with a marginally stably oscillator, that poses a
problem. How long do I wait to find a mean frequency to type in...? It
makes total sense why this is so in TI mode, but still it's one more thing
to deal with.

I think I'll stick with frequency mode for most things. Many of the
oscillators I want to measure are right around 10^-8 or 10^-9, and I'd hate
to constantly be fighting the noise floor of the instrument. I'll treat the
data from frequency mode as relative and that should get me what I need. At
least until I own a better instrument.


Thanks

Dan

On Tue, Jun 30, 2015 at 10:49 PM, John Miles j...@miles.io wrote:

 Yep, it will ignore any non-numeric data like us suffixes.  It will
 always interpret incoming data as seconds, so the 1E-6 scale factor is
 appropriate if the counter is returning microseconds.  I'll tweak the
 mouseover help text for the scale factor field to clarify that.

 I think you're basically getting valid data.  The 53131A's one-shot
 resolution is 0.5 ns, and you're seeing about 2E-9 residual ADEV at t=1s.
 It's in the right ballpark, anyway... e.g., on a 20-ps HP 5370, the
 residual ADEV at t=1s will usually be in the neighborhood of 30-60 ps.

 I would, however, be worried about aliasing with a TCXO.  If its frequency
 is more than 5E-8 off -- meaning it drifts more than 50 nanoseconds per
 second with 10 MHz at the STOP jack --  its error will end up
 underrepresented in the measurement.  In this case your oscillator is
 drifting quite a bit (as expected) -- look at the 'w' view of the original
 phase compared to the unwrapped 'p' phase.  You could try putting 1pps on
 both the START and STOP jacks but that'll require more futzing with scale
 factors, 1pps dividers and the like, and may leave you more vulnerable to
 trigger uncertainty from various causes.  For measurement of a TCXO, I'd
 stick with frequency mode.  The ADEV plots won't be 100% kosher but they'll
 be fine for relative comparisons with other plots from the same measurement
 setup.

 -- john, KE5FX
 Miles Design LLC


  -Original Message-
  From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan
  Watson
  Sent: Tuesday, June 30, 2015 5:05 PM
  To: Discussion of precise time and frequency measurement
  Subject: Re: [time-nuts] Help with my ADEV measurement setup
 
  I tried both the PPS and the 10MHz signal on channel 1, with the 10MHz
 DUT
  on channel 2. Tom emailed me and it turns out the software was not
  detecting the units correctly from the serial string. (What are 6 powers
 of
  ten between friends, right? :) ) Likely a settings mistake on my part, I
  sent him a screen cap to see what's up.
 
  None the less, I manually enter the time units and was able to plot some
  data. I attached a new screen cap. How does this look?
 
  Thanks
 
  Dan
 
  On Tue, Jun 30, 2015 at 5:36 PM, Bob Camp kb...@n1k.org wrote:
 
   Hi
  
   Are you using a PPS as the “start” and the 10 MHz as the “stop” or
   comparing two PPS signals?
  
   Bob
  
On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com
  wrote:
   
Hi,
   
I'm trying to take some ADEV measurements with my 53131A, and I'm
  having
some issues. This is my setup:
   
- 53131A with the OCXO option. Calibrated against a T-bolt. I also
 did
   the
TI Quik cal and it passed
- I'm using RS-232 out with a null modem cable into a Serial-USB
   converter
- Software is TimeLab in talk-only mode. 53131A check box is checked.
- The counter is in TI mode, with a T-bolt on Channel 1 and DUT on
   Channel 2
- A delay of 1 second is set on the counter. TimeLab seems to
 accurately
detect this interval
   
I started measuring various devices, and could never seem to get
 better
than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6.
Finally I put the T-bolt on channel 1 with common mode on to both
   channels,
and it still measures around 10^-6. A picture of that is attached.
 Surely
this can't be right.
   
I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and
 T-bolt,
as expected. I understand the issues with filtering that the 53131A
 does
internally on this mode, but at least it shows my setup is working to
   some
degree. It's TI mode that seems to be wonky.
   
I'm probably doing something really stupid.
   
Thanks for any help you all can suggest.
   
Regards,
   
Dan W

Re: [time-nuts] Help with my ADEV measurement setup

[Dan Watson]

I tried both the PPS and the 10MHz signal on channel 1, with the 10MHz DUT
on channel 2. Tom emailed me and it turns out the software was not
detecting the units correctly from the serial string. (What are 6 powers of
ten between friends, right? :) ) Likely a settings mistake on my part, I
sent him a screen cap to see what's up.

None the less, I manually enter the time units and was able to plot some
data. I attached a new screen cap. How does this look?

Thanks

Dan

On Tue, Jun 30, 2015 at 5:36 PM, Bob Camp kb...@n1k.org wrote:

 Hi

 Are you using a PPS as the “start” and the 10 MHz as the “stop” or
 comparing two PPS signals?

 Bob

  On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com wrote:
 
  Hi,
 
  I'm trying to take some ADEV measurements with my 53131A, and I'm having
  some issues. This is my setup:
 
  - 53131A with the OCXO option. Calibrated against a T-bolt. I also did
 the
  TI Quik cal and it passed
  - I'm using RS-232 out with a null modem cable into a Serial-USB
 converter
  - Software is TimeLab in talk-only mode. 53131A check box is checked.
  - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on
 Channel 2
  - A delay of 1 second is set on the counter. TimeLab seems to accurately
  detect this interval
 
  I started measuring various devices, and could never seem to get better
  than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6.
  Finally I put the T-bolt on channel 1 with common mode on to both
 channels,
  and it still measures around 10^-6. A picture of that is attached. Surely
  this can't be right.
 
  I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt,
  as expected. I understand the issues with filtering that the 53131A does
  internally on this mode, but at least it shows my setup is working to
 some
  degree. It's TI mode that seems to be wonky.
 
  I'm probably doing something really stupid.
 
  Thanks for any help you all can suggest.
 
  Regards,
 
  Dan W
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Re: [time-nuts] Help with my ADEV measurement setup

[Bob Camp]

Hi

Your OCXO and the TBolt *should* be down around 1x10^-11 to 1x10^-12 at one 
second. 
That’s a factor of 10 to 100X better than the 53131 can do at a random 
frequency. At exactly
10 MHz it may be even worse than that. Effectively what you will be doing is 
measuring the 
noise floor of the counter out to a few hundred seconds. To get useful data, 
plan on runs of
at least several hours, if not a few days. 

Bob

 On Jun 30, 2015, at 8:05 PM, Dan Watson watsondani...@gmail.com wrote:
 
 I tried both the PPS and the 10MHz signal on channel 1, with the 10MHz DUT
 on channel 2. Tom emailed me and it turns out the software was not
 detecting the units correctly from the serial string. (What are 6 powers of
 ten between friends, right? :) ) Likely a settings mistake on my part, I
 sent him a screen cap to see what's up.
 
 None the less, I manually enter the time units and was able to plot some
 data. I attached a new screen cap. How does this look?
 
 Thanks
 
 Dan
 
 On Tue, Jun 30, 2015 at 5:36 PM, Bob Camp kb...@n1k.org wrote:
 
 Hi
 
 Are you using a PPS as the “start” and the 10 MHz as the “stop” or
 comparing two PPS signals?
 
 Bob
 
 On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com wrote:
 
 Hi,
 
 I'm trying to take some ADEV measurements with my 53131A, and I'm having
 some issues. This is my setup:
 
 - 53131A with the OCXO option. Calibrated against a T-bolt. I also did
 the
 TI Quik cal and it passed
 - I'm using RS-232 out with a null modem cable into a Serial-USB
 converter
 - Software is TimeLab in talk-only mode. 53131A check box is checked.
 - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on
 Channel 2
 - A delay of 1 second is set on the counter. TimeLab seems to accurately
 detect this interval
 
 I started measuring various devices, and could never seem to get better
 than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6.
 Finally I put the T-bolt on channel 1 with common mode on to both
 channels,
 and it still measures around 10^-6. A picture of that is attached. Surely
 this can't be right.
 
 I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt,
 as expected. I understand the issues with filtering that the 53131A does
 internally on this mode, but at least it shows my setup is working to
 some
 degree. It's TI mode that seems to be wonky.
 
 I'm probably doing something really stupid.
 
 Thanks for any help you all can suggest.
 
 Regards,
 
 Dan W
 adevtest.png___
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Re: [time-nuts] Help with my ADEV measurement setup

[John Miles]

Let's see a snapshot of your acquisition dialog, just before you hit 'Start'.  
(Or send me a .tim file directly.)  It can be tricky to configure the test 
setup for a TI measurement, since so many more things can go wrong compared to 
a frequency-based setup.

-- john, KE5FX
Miles Design LLC

 -Original Message-
 From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan
 Watson
 Sent: Tuesday, June 30, 2015 11:48 AM
 To: time-nuts@febo.com
 Subject: [time-nuts] Help with my ADEV measurement setup
 
 Hi,
 
 I'm trying to take some ADEV measurements with my 53131A, and I'm having
 some issues. This is my setup...

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Re: [time-nuts] Help with my ADEV measurement setup

[Dan Watson]

Attached is a screenshot of the setup window. I manually typed in 1E-6 as
the units. I also hit Monitor and let it average the reporting interval for
a while until it settled at 1.00 seconds.

Originally I was leaving the time unit as 1, and microseconds in in the
serial string was not being detected to set the units automatically.

I'd be happy to send you a tim file as well if necessary. Let me know.

Thanks

Dan

On Tue, Jun 30, 2015 at 8:51 PM, John Miles j...@miles.io wrote:

 Let's see a snapshot of your acquisition dialog, just before you hit
 'Start'.  (Or send me a .tim file directly.)  It can be tricky to configure
 the test setup for a TI measurement, since so many more things can go wrong
 compared to a frequency-based setup.

 -- john, KE5FX
 Miles Design LLC

  -Original Message-
  From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan
  Watson
  Sent: Tuesday, June 30, 2015 11:48 AM
  To: time-nuts@febo.com
  Subject: [time-nuts] Help with my ADEV measurement setup
 
  Hi,
 
  I'm trying to take some ADEV measurements with my 53131A, and I'm having
  some issues. This is my setup...

 ___
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Re: [time-nuts] Help with my ADEV measurement setup

[John Miles]

Yep, it will ignore any non-numeric data like us suffixes.  It will always 
interpret incoming data as seconds, so the 1E-6 scale factor is appropriate if 
the counter is returning microseconds.  I'll tweak the mouseover help text for 
the scale factor field to clarify that.  

I think you're basically getting valid data.  The 53131A's one-shot resolution 
is 0.5 ns, and you're seeing about 2E-9 residual ADEV at t=1s.  It's in the 
right ballpark, anyway... e.g., on a 20-ps HP 5370, the residual ADEV at t=1s 
will usually be in the neighborhood of 30-60 ps. 

I would, however, be worried about aliasing with a TCXO.  If its frequency is 
more than 5E-8 off -- meaning it drifts more than 50 nanoseconds per second 
with 10 MHz at the STOP jack --  its error will end up underrepresented in the 
measurement.  In this case your oscillator is drifting quite a bit (as 
expected) -- look at the 'w' view of the original phase compared to the 
unwrapped 'p' phase.  You could try putting 1pps on both the START and STOP 
jacks but that'll require more futzing with scale factors, 1pps dividers and 
the like, and may leave you more vulnerable to trigger uncertainty from various 
causes.  For measurement of a TCXO, I'd stick with frequency mode.  The ADEV 
plots won't be 100% kosher but they'll be fine for relative comparisons with 
other plots from the same measurement setup.

-- john, KE5FX
Miles Design LLC


 -Original Message-
 From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan
 Watson
 Sent: Tuesday, June 30, 2015 5:05 PM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Help with my ADEV measurement setup
 
 I tried both the PPS and the 10MHz signal on channel 1, with the 10MHz DUT
 on channel 2. Tom emailed me and it turns out the software was not
 detecting the units correctly from the serial string. (What are 6 powers of
 ten between friends, right? :) ) Likely a settings mistake on my part, I
 sent him a screen cap to see what's up.
 
 None the less, I manually enter the time units and was able to plot some
 data. I attached a new screen cap. How does this look?
 
 Thanks
 
 Dan
 
 On Tue, Jun 30, 2015 at 5:36 PM, Bob Camp kb...@n1k.org wrote:
 
  Hi
 
  Are you using a PPS as the “start” and the 10 MHz as the “stop” or
  comparing two PPS signals?
 
  Bob
 
   On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com
 wrote:
  
   Hi,
  
   I'm trying to take some ADEV measurements with my 53131A, and I'm
 having
   some issues. This is my setup:
  
   - 53131A with the OCXO option. Calibrated against a T-bolt. I also did
  the
   TI Quik cal and it passed
   - I'm using RS-232 out with a null modem cable into a Serial-USB
  converter
   - Software is TimeLab in talk-only mode. 53131A check box is checked.
   - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on
  Channel 2
   - A delay of 1 second is set on the counter. TimeLab seems to accurately
   detect this interval
  
   I started measuring various devices, and could never seem to get better
   than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6.
   Finally I put the T-bolt on channel 1 with common mode on to both
  channels,
   and it still measures around 10^-6. A picture of that is attached. Surely
   this can't be right.
  
   I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt,
   as expected. I understand the issues with filtering that the 53131A does
   internally on this mode, but at least it shows my setup is working to
  some
   degree. It's TI mode that seems to be wonky.
  
   I'm probably doing something really stupid.
  
   Thanks for any help you all can suggest.
  
   Regards,
  
   Dan W
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[time-nuts] Help with my ADEV measurement setup

[Dan Watson]

Hi,

I'm trying to take some ADEV measurements with my 53131A, and I'm having
some issues. This is my setup:

- 53131A with the OCXO option. Calibrated against a T-bolt. I also did the
TI Quik cal and it passed
- I'm using RS-232 out with a null modem cable into a Serial-USB converter
- Software is TimeLab in talk-only mode. 53131A check box is checked.
- The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2
- A delay of 1 second is set on the counter. TimeLab seems to accurately
detect this interval

I started measuring various devices, and could never seem to get better
than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6.
Finally I put the T-bolt on channel 1 with common mode on to both channels,
and it still measures around 10^-6. A picture of that is attached. Surely
this can't be right.

I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt,
as expected. I understand the issues with filtering that the 53131A does
internally on this mode, but at least it shows my setup is working to some
degree. It's TI mode that seems to be wonky.

I'm probably doing something really stupid.

Thanks for any help you all can suggest.

Regards,

Dan W
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Re: [time-nuts] Help with my ADEV measurement setup

[Bob Camp]

Hi

Are you using a PPS as the “start” and the 10 MHz as the “stop” or comparing 
two PPS signals?

Bob

 On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com wrote:
 
 Hi,
 
 I'm trying to take some ADEV measurements with my 53131A, and I'm having
 some issues. This is my setup:
 
 - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the
 TI Quik cal and it passed
 - I'm using RS-232 out with a null modem cable into a Serial-USB converter
 - Software is TimeLab in talk-only mode. 53131A check box is checked.
 - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2
 - A delay of 1 second is set on the counter. TimeLab seems to accurately
 detect this interval
 
 I started measuring various devices, and could never seem to get better
 than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6.
 Finally I put the T-bolt on channel 1 with common mode on to both channels,
 and it still measures around 10^-6. A picture of that is attached. Surely
 this can't be right.
 
 I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt,
 as expected. I understand the issues with filtering that the 53131A does
 internally on this mode, but at least it shows my setup is working to some
 degree. It's TI mode that seems to be wonky.
 
 I'm probably doing something really stupid.
 
 Thanks for any help you all can suggest.
 
 Regards,
 
 Dan W
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Re: [time-nuts] Help me make some sense of adev measurements of SR620'sown clock

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 25 Jan 2015 23:02, Tom Van Baak t...@leapsecond.com wrote:

 You're getting 1e-12 at 1 second. Sounds fine to me.

Obviously you have the experience to know that 1e-12 at 1 second is fine.

But if it's possible,  I would like to understand the relationship between
the counters specification and the adev (or one of the modifications of it)
one would expect to see.

Obviously it is nice to know that the counter is working ok, but I would
like to understand how one can ascertain that from the data I recorded,
based on the SR620's specifications.

 Also, when you plot phase with TimeLab you'll notice a jump around
T+23600 seconds. This is likely you breathing near the instrument, or
touching a cable, or closing a door.

That's interesting.  It is about 4:30 am local time here, so when I was
asleep. I would have expected data then to be better than during the day
when I move around. The biggest disturbance occurred at a time I would have
least expected it.

  Do most people save time information as I have done there, or phase
  information?

 Always save phase. Not sure what you mean by time.
The counter can measure the time between the start and stop inputs, which
is what I done. The numbers are around 17.5 ns due to the cable length.

But instead of saving those time values, I could have configured the
counter to save the phase in the range -180 to +180 degrees. Your adev1
programe expected time in seconds rather than phase in degrees, which is
why I saved time rather than phase.  But I will use adev5 as you
suggested.  I used adev1 primarily since you had a web page on it.

I am not talking about elapsed time, time of the day etc. That's something
quite different.

 Even better is to save both phase and elapsed time or real time; the
latter can be used as a check that your sample rates are what you expect.

I did save elapsed time as you can see. I was in fact a bit surprised that
the data points are spaced very slightly *less* than a second apart. I
would have expected the data to take 1 second to collect, then some time
processing time, especially since I introduced a delay of about 200 us to
stop the GPIB reads randomly failing.   That's a bit of a mystery.

 Personally, I prefix every ascii line received with a MJD timestamp. That
way all my log files, everything from counters to temperature sensors to
GPS NMEA lines can all be correlated against themselves and with other
people.

I had never heard of the MJD, but I will do what you suggest.

  Data collection started at: 23:2:55 GMT on 24/01/2015 (day/month/year
format)

 Always use leading zeros for hours, minutes, and seconds.

That was not intensional. I would have intended to put the leading zero.

 The preferred way to write this is simply 2015-01-24 23:02:55 (see ISO
8601).

OK, I'll do that, despite it seems quite unnatural to us brits!

John's software looks impressive. In fact is TimePod hardware too, but far
out of my budget. I will have to make do with the SR620.

I just wish I didn't have to load the data into a Windows program. Maybe at
some point I will try to get gnuplot to do similar.

 /tvb

Thank you Tom. Also to Bob. I will do as Bob suggested and repeat using an
external 10 MHz source, rather than use the counters own timebase.

Dave
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Re: [time-nuts] Help me make some sense of adev measurements of SR620's own clock

[Bob Camp]

HI

If you want to check your counter, simply look at the standard deviation of the 
readings you are getting. When I put them in to Excel here, they come up at 
6.944 ps. That’s well within the counter’s specs. It’s not at all uncommon with 
the SR620 to get “to good to be true” readings using the internal standard. The 
reason is that the noise on the standard cancels out to some degree when you 
use it as your test source. To get a more realistic number, feed it with a 10 
MHz source that is not the same as it’s internal reference. 

Bob

 On Jan 25, 2015, at 10:43 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
 drkir...@kirkbymicrowave.co.uk wrote:
 
 After sorting out some GPIB issues, I finally got to be able to make
 some measurements on my Stanford Research SR620 time-interval counter.
 I thought it sensible to first try to determine the performance of the
 counter, which is using its own high stability clock (option 001). So
 no external reference, such as one derived from GPS, is used.
 
 I took the 10 MHz reference output from the SR620 via a cable about
 0.5 m to the A input of the counter, which also had a BNC T on the
 counter. From the A input to the B input is a cable about 3.6 m long
 (longer than I would have liked with hindsight). I then measured the
 time-interval every second for 55488 seconds - it is actually still
 collecting data. The data file is here.
 
 http://www.kirkbymicrowave.co.uk/time-stuff/ref-out-to-A-3.6m-cable-to-B-rev4.zip
 
 The format should be pretty self-explanatory. Note the counter sample
 size is 1000, so it takes 1 sec. Note A is an high impedance input,
 and B 50 Ohms, which seems a logical choice if tapping off a bit from
 a 50 Ohm cable for the A input.
 
 # Data collected with ./tic version 0.01
 # GPIB address 17 on host 'buzzard'
 # Data collection started at: 23:2:55 GMT on 24/01/2015 (day/month/year 
 format)
 # Instrument settings are as follows:
 # Sample size: 1E3
 # Trigger level (external): -0.21 V
 # Trigger level (A): -0.01 V
 # Trigger level (B): -0.01 V
 # Coupling (A): AC
 # Coupling (B): AC
 # Termination (external): 100 Ohm
 # Termination (A): 100 Ohm
 # Termination (B): 50 Ohm
 # Mode = Time
 # Column 1 is the time from the SR620 in seconds
 # Column 2 is a hash(#) character, used to denote a comment
 # Column 3 is the delay in seconds since data was first collected
 1.7540E-8 # 0.00 s
 1.7538E-8 # 0.988158 s
 1.7538E-8 # 1.976571 s
 1.7538E-8 # 2.964327 s
 
 The times recorded, about 17.5 ns, are consistent with what one would
 expect with a cable about the length I have.
 
 I then used Tom's adev1
 
 http://www.leapsecond.com/tools/adev1.htm
 http://www.leapsecond.com/tools/adev1.c
 
 to analyze the data.
 
 drkirkby@buzzard:/tmp$ adev1 1  ref-out-to-A-3.6m-cable-to-B.txt
 
 ** Sampling period: 1 s
 ** Phase data scale factor: 1.000e+00
 ** Total phase samples: 56165
 ** Normal and Overlapping Allan deviation:
 
   1 tau, 1.0066e-12 adev(n=56163), 1.0066e-12 oadev(n=56163)
   2 tau, 5.2611e-13 adev(n=28081), 5.2820e-13 oadev(n=56161)
   5 tau, 2.4461e-13 adev(n=11231), 2.4397e-13 oadev(n=56155)
  10 tau, 1.5235e-13 adev(n=5615),  1.5188e-13 oadev(n=56145)
  20 tau, 9.8477e-14 adev(n=2807),  9.9323e-14 oadev(n=56125)
  50 tau, 5.7764e-14 adev(n=1122),  5.9520e-14 oadev(n=56065)
 100 tau, 4.1609e-14 adev(n=560),   4.2643e-14 oadev(n=55965)
 200 tau, 2.7712e-14 adev(n=279),   2.8362e-14 oadev(n=55765)
 500 tau, 8.1848e-15 adev(n=111),   9.3519e-15 oadev(n=55165)
1000 tau, 4.9553e-15 adev(n=55),5.2360e-15 oadev(n=54165)
2000 tau, 3.3500e-15 adev(n=27),3.0661e-15 oadev(n=52165)
5000 tau, 1.8873e-15 adev(n=10),1.4325e-15 oadev(n=46165)
   1 tau, 8.6819e-16 adev(n=4), 8.6732e-16 oadev(n=36165)
   2 tau, 1.4849e-15 adev(n=1), 6.3165e-16 oadev(n=16165)
 
 I'm puzzled about, is how to interpret this, and if interpretation is
 correct, my counter might not be in spec.
 
 I thought from reading Wikipedia and
 
 en.wikipedia.org/wiki/Allan_variance
 
 that at 1 tau, the Allen Deviation represents the RMS deviation
 between two observations 1 second apart.  So that is 1.0066 ps.
 
 The SR620 counter's display has resolution of 1 ps, and supposedly a
 25 ps rms single short resolution. Would I be right in assuming that
 after 1 second (1000 samples), I would expect to see an adev of
 25e-12/sqrt(1000) = 8e-13, suggesting my counter is not achieving the
 25 ps rms resolution, but rather sqrt(1000)*1.0066e-12=31.8 ps? I've
 run Autocal on this counter, and put the oscillator on frequency with
 one of the calbytes, but have not done any other adjustments. Needless
 to say its an eBay purchase, and I doubt has been near a cal lab in
 years.
 
 Again based on a 25 ps rms resolution, would I expect after 500
 seconds (50,000 counts), to see an adev of 25e-12/sqrt(5)=1.118 x
 10^-13, rather than the 8.1848e-15 the 

Re: [time-nuts] Help me make some sense of adev measurements of SR620'sown clock

[Tom Van Baak]

 http://www.kirkbymicrowave.co.uk/time-stuff/ref-out-to-A-3.6m-cable-to-B-rev4.zip
 
 The format should be pretty self-explanatory. Note the counter sample

Well done, nicely self-documenting.

 I then used Tom's adev1
 
 http://www.leapsecond.com/tools/adev1.htm
 http://www.leapsecond.com/tools/adev1.c
 
 to analyze the data.

That will work, but adev5 is a more recent version that I now use instead.

C:\tmpskip 17  ref-out-to-A-3.6m-cable-to-B.txt | fld 1 | adev5 /a 0 10 .5
** log(tau) from 0 to 10 step 0.5, that is, tau from 1 to 1e+010 with 2 
steps/decade
  0.   1 a -11.997131 1.006628e-012 56163
  0.5000   3 a -12.432202 3.696563e-013 56159
  1.  10 a -12.818504 1.518784e-013 56145
  1.5000  32 a -13.123597 7.523206e-014 56101
  2. 100 a -13.370151 4.264311e-014 55965
  2.5000 316 a -13.787569 1.630914e-014 55533
  3.1000 a -14.280998 5.236028e-015 54165
  3.50003162 a -14.694447 2.020940e-015 49841
  4.   1 a -15.061822 8.673176e-016 36165

Better yet, use John's TimeLab, import with 'L' and see nice phase, frequency, 
adev, tdev plots within seconds. Here are the plots you will get:
http://leapsecond.com/tmp/dave1-phase.gif
http://leapsecond.com/tmp/dave1-freq.gif
http://leapsecond.com/tmp/dave1-adev.gif
http://leapsecond.com/tmp/dave1-tdev.gif
http://leapsecond.com/tmp/dave1-tdev10.gif

 I'm puzzled about, is how to interpret this, and if interpretation is
 correct, my counter might not be in spec.

Your interpretation is correct. You can also get TDEV numbers using adev5 /t

 The SR620 counter's display has resolution of 1 ps, and supposedly a
 25 ps rms single short resolution. Would I be right in assuming that
 after 1 second (1000 samples), I would expect to see an adev of
 25e-12/sqrt(1000) = 8e-13, suggesting my counter is not achieving the
 25 ps rms resolution, but rather sqrt(1000)*1.0066e-12=31.8 ps?

You're getting 1e-12 at 1 second. Sounds fine to me. Don't sweat the 10 vs 9 vs 
8e-13 thing; the counter is working fine. The TDEV gets down to 4e-13 at 4 
seconds if you want nice numbers. You're partly limited by 1 ps LSDigit 
quantization as well.

 Also, why would the adev rise at 2 tau, when this is only
 measuring the time between its own reference, and a version delayed by
 about 17.5 ns due to a few metres of cable? But maybe there's not
 really enough data at 2 seconds.

There are many things hidden inside the word measuring itself. Internal and 
external enviromental effects will start to play a role in this time frame.

Also, when you plot phase with TimeLab you'll notice a jump around T+23600 
seconds. This is likely you breathing near the instrument, or touching a cable, 
or closing a door. We're talking ps here, so you can't even look at it while 
it's running.

 Do most people save time information as I have done there, or phase
 information? I'm guessing the two are easily related, but I'm
 wondering what will work with most peoples software. What I like about
 Tom's is it compiles easily on my Unix box, without me having to use
 Windows. But I note some of Tom's software wants phase, and the other
 time.

Always save phase. Not sure what you mean by time. Even better is to save both 
phase and elapsed time or real time; the latter can be used as a check that 
your sample rates are what you expect.

Personally, I prefix every ascii line received with a MJD timestamp. That way 
all my log files, everything from counters to temperature sensors to GPS NMEA 
lines can all be correlated against themselves and with other people.

 Data collection started at: 23:2:55 GMT on 24/01/2015 (day/month/year format)

Always use leading zeros for hours, minutes, and seconds. The preferred way to 
write this is simply 2015-01-24 23:02:55 (see ISO 8601).

/tvb
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[time-nuts] Help me make some sense of adev measurements of SR620's own clock

[Dr. David Kirkby (Kirkby Microwave Ltd)]

After sorting out some GPIB issues, I finally got to be able to make
some measurements on my Stanford Research SR620 time-interval counter.
I thought it sensible to first try to determine the performance of the
counter, which is using its own high stability clock (option 001). So
no external reference, such as one derived from GPS, is used.

I took the 10 MHz reference output from the SR620 via a cable about
0.5 m to the A input of the counter, which also had a BNC T on the
counter. From the A input to the B input is a cable about 3.6 m long
(longer than I would have liked with hindsight). I then measured the
time-interval every second for 55488 seconds - it is actually still
collecting data. The data file is here.

http://www.kirkbymicrowave.co.uk/time-stuff/ref-out-to-A-3.6m-cable-to-B-rev4.zip

The format should be pretty self-explanatory. Note the counter sample
size is 1000, so it takes 1 sec. Note A is an high impedance input,
and B 50 Ohms, which seems a logical choice if tapping off a bit from
a 50 Ohm cable for the A input.

# Data collected with ./tic version 0.01
# GPIB address 17 on host 'buzzard'
# Data collection started at: 23:2:55 GMT on 24/01/2015 (day/month/year format)
# Instrument settings are as follows:
# Sample size: 1E3
# Trigger level (external): -0.21 V
# Trigger level (A): -0.01 V
# Trigger level (B): -0.01 V
# Coupling (A): AC
# Coupling (B): AC
# Termination (external): 100 Ohm
# Termination (A): 100 Ohm
# Termination (B): 50 Ohm
# Mode = Time
# Column 1 is the time from the SR620 in seconds
# Column 2 is a hash(#) character, used to denote a comment
# Column 3 is the delay in seconds since data was first collected
1.7540E-8 # 0.00 s
1.7538E-8 # 0.988158 s
1.7538E-8 # 1.976571 s
1.7538E-8 # 2.964327 s

The times recorded, about 17.5 ns, are consistent with what one would
expect with a cable about the length I have.

I then used Tom's adev1

http://www.leapsecond.com/tools/adev1.htm
http://www.leapsecond.com/tools/adev1.c

to analyze the data.

drkirkby@buzzard:/tmp$ adev1 1  ref-out-to-A-3.6m-cable-to-B.txt

** Sampling period: 1 s
** Phase data scale factor: 1.000e+00
** Total phase samples: 56165
** Normal and Overlapping Allan deviation:

   1 tau, 1.0066e-12 adev(n=56163), 1.0066e-12 oadev(n=56163)
   2 tau, 5.2611e-13 adev(n=28081), 5.2820e-13 oadev(n=56161)
   5 tau, 2.4461e-13 adev(n=11231), 2.4397e-13 oadev(n=56155)
  10 tau, 1.5235e-13 adev(n=5615),  1.5188e-13 oadev(n=56145)
  20 tau, 9.8477e-14 adev(n=2807),  9.9323e-14 oadev(n=56125)
  50 tau, 5.7764e-14 adev(n=1122),  5.9520e-14 oadev(n=56065)
 100 tau, 4.1609e-14 adev(n=560),   4.2643e-14 oadev(n=55965)
 200 tau, 2.7712e-14 adev(n=279),   2.8362e-14 oadev(n=55765)
 500 tau, 8.1848e-15 adev(n=111),   9.3519e-15 oadev(n=55165)
1000 tau, 4.9553e-15 adev(n=55),5.2360e-15 oadev(n=54165)
2000 tau, 3.3500e-15 adev(n=27),3.0661e-15 oadev(n=52165)
5000 tau, 1.8873e-15 adev(n=10),1.4325e-15 oadev(n=46165)
   1 tau, 8.6819e-16 adev(n=4), 8.6732e-16 oadev(n=36165)
   2 tau, 1.4849e-15 adev(n=1), 6.3165e-16 oadev(n=16165)

I'm puzzled about, is how to interpret this, and if interpretation is
correct, my counter might not be in spec.

I thought from reading Wikipedia and

en.wikipedia.org/wiki/Allan_variance

that at 1 tau, the Allen Deviation represents the RMS deviation
between two observations 1 second apart.  So that is 1.0066 ps.

The SR620 counter's display has resolution of 1 ps, and supposedly a
25 ps rms single short resolution. Would I be right in assuming that
after 1 second (1000 samples), I would expect to see an adev of
25e-12/sqrt(1000) = 8e-13, suggesting my counter is not achieving the
25 ps rms resolution, but rather sqrt(1000)*1.0066e-12=31.8 ps? I've
run Autocal on this counter, and put the oscillator on frequency with
one of the calbytes, but have not done any other adjustments. Needless
to say its an eBay purchase, and I doubt has been near a cal lab in
years.

Again based on a 25 ps rms resolution, would I expect after 500
seconds (50,000 counts), to see an adev of 25e-12/sqrt(5)=1.118 x
10^-13, rather than the 8.1848e-15 the data shows?

Also, why would the adev rise at 2 tau, when this is only
measuring the time between its own reference, and a version delayed by
about 17.5 ns due to a few metres of cable? But maybe there's not
really enough data at 2 seconds.

Do most people save time information as I have done there, or phase
information? I'm guessing the two are easily related, but I'm
wondering what will work with most peoples software. What I like about
Tom's is it compiles easily on my Unix box, without me having to use
Windows. But I note some of Tom's software wants phase, and the other
time.

I'm still collecting data, so will at some point upload a larger file
to http://www.kirkbymicrowave.co.uk/time-stuff/ with more data. I'll
certainly 

Re: [time-nuts] Help me make some sense of adev measurements of SR620'sown clock

[Magnus Danielson]

David,

Looking at the ADEV plot, I see the ripple that I expect from some 
oscillatory property.


Looking at the phase, I see some of it, and picking it up in fityk (to 
view the phase info) I see a sawtooth like pattern, seeing typ around 4 
cycles in 2000 s or so, which is typical of heating/AC type of 
behaviour. Hence, I may be looking at a temp-sensor.


Shielding from temperature-variations can be tricky, as the SR620 
produces a lot of heat. Putting thermal mass all around it 
(waterbottles) might be a fun experiment, but for most part, I think the 
performance you get is good and you should not be bothered with it.


The ADEV measure you got that was higher had only one degree of freedom, 
so the confidence interval was very wide, so you should just ignore 
that. You should look at the oadev list instead.


Cheers,
Magnus

On 01/25/2015 11:21 PM, Tom Van Baak wrote:

http://www.kirkbymicrowave.co.uk/time-stuff/ref-out-to-A-3.6m-cable-to-B-rev4.zip

The format should be pretty self-explanatory. Note the counter sample


Well done, nicely self-documenting.


I then used Tom's adev1

http://www.leapsecond.com/tools/adev1.htm
http://www.leapsecond.com/tools/adev1.c

to analyze the data.


That will work, but adev5 is a more recent version that I now use instead.

C:\tmpskip 17  ref-out-to-A-3.6m-cable-to-B.txt | fld 1 | adev5 /a 0 10 .5
** log(tau) from 0 to 10 step 0.5, that is, tau from 1 to 1e+010 with 2 
steps/decade
   0.   1 a -11.997131 1.006628e-012 56163
   0.5000   3 a -12.432202 3.696563e-013 56159
   1.  10 a -12.818504 1.518784e-013 56145
   1.5000  32 a -13.123597 7.523206e-014 56101
   2. 100 a -13.370151 4.264311e-014 55965
   2.5000 316 a -13.787569 1.630914e-014 55533
   3.1000 a -14.280998 5.236028e-015 54165
   3.50003162 a -14.694447 2.020940e-015 49841
   4.   1 a -15.061822 8.673176e-016 36165

Better yet, use John's TimeLab, import with 'L' and see nice phase, frequency, 
adev, tdev plots within seconds. Here are the plots you will get:
http://leapsecond.com/tmp/dave1-phase.gif
http://leapsecond.com/tmp/dave1-freq.gif
http://leapsecond.com/tmp/dave1-adev.gif
http://leapsecond.com/tmp/dave1-tdev.gif
http://leapsecond.com/tmp/dave1-tdev10.gif


I'm puzzled about, is how to interpret this, and if interpretation is
correct, my counter might not be in spec.


Your interpretation is correct. You can also get TDEV numbers using adev5 /t


The SR620 counter's display has resolution of 1 ps, and supposedly a
25 ps rms single short resolution. Would I be right in assuming that
after 1 second (1000 samples), I would expect to see an adev of
25e-12/sqrt(1000) = 8e-13, suggesting my counter is not achieving the
25 ps rms resolution, but rather sqrt(1000)*1.0066e-12=31.8 ps?


You're getting 1e-12 at 1 second. Sounds fine to me. Don't sweat the 10 vs 9 vs 
8e-13 thing; the counter is working fine. The TDEV gets down to 4e-13 at 4 
seconds if you want nice numbers. You're partly limited by 1 ps LSDigit 
quantization as well.


Also, why would the adev rise at 2 tau, when this is only
measuring the time between its own reference, and a version delayed by
about 17.5 ns due to a few metres of cable? But maybe there's not
really enough data at 2 seconds.


There are many things hidden inside the word measuring itself. Internal and 
external enviromental effects will start to play a role in this time frame.

Also, when you plot phase with TimeLab you'll notice a jump around T+23600 
seconds. This is likely you breathing near the instrument, or touching a cable, 
or closing a door. We're talking ps here, so you can't even look at it while 
it's running.


Do most people save time information as I have done there, or phase
information? I'm guessing the two are easily related, but I'm
wondering what will work with most peoples software. What I like about
Tom's is it compiles easily on my Unix box, without me having to use
Windows. But I note some of Tom's software wants phase, and the other
time.


Always save phase. Not sure what you mean by time. Even better is to save both 
phase and elapsed time or real time; the latter can be used as a check that 
your sample rates are what you expect.

Personally, I prefix every ascii line received with a MJD timestamp. That way 
all my log files, everything from counters to temperature sensors to GPS NMEA 
lines can all be correlated against themselves and with other people.


Data collection started at: 23:2:55 GMT on 24/01/2015 (day/month/year format)


Always use leading zeros for hours, minutes, and seconds. The preferred way to 
write this is simply 2015-01-24 23:02:55 (see ISO 8601).

/tvb
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Re: [time-nuts] Help identifying a display board

[ed breya]

It could be a combined time display with a channel number and 
measured value, from some kind of data logging instrument. LN was 
big in thermocouple measurements and the like. With those digits you 
could show temperature at three digits resolution, selected channel 
00-99, and hours and minutes, with the LED for AM/PM.


Or NOT.

One clue would be to see if they used any of the Panaplex decimal 
points. None would be needed on time or channel readouts. If only the 
second DP of the three-digit one is connected, then it could be set 
to 1 or 0.1 degree resolution. If no DPs at all are used, then the 
temperature could show 1 degree resolution, and display -99 to 999 
deg F or C, which is a pretty decent range for common T/Cs, depending 
on the application. It could even work for cryogenics, reading say 
000-999 deg K.


The board also appears to be missing one DM8880.

Ed

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[time-nuts] Help identifying a display board

[Dan Veeneman]

Over the weekend I picked up a display board that appears to have come
from a clock or time code device.  It has four Panaplex display modules
and a single LED.  The board is silkscreened with a LN logo and
appears to be circa 1974 (if what looks like a date code is actually a
date code).

I have pictures up at
http://www.decodesystems.com/help-wanted/index.html#panaplex.  Does
anyone recognize the logo and/or the device this board might have come from?


Thanks,
Dan
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Re: [time-nuts] Help identifying a display board

[Robert LaJeunesse]

Sure looks like Leeds  Northrup to me.

http://www.ebay.com/itm/Leeds-and-Northrup-Light-Beam-Galvanometer-2430-C-/281460565063?pt=LH_DefaultDomain_0hash=item41885b6447

Bob L.

 Sent: Wednesday, October 08, 2014 at 2:41 PM
 From: Dan Veeneman d...@decodesystems.com
 To: time-nuts@febo.com
 Subject: [time-nuts] Help identifying a display board

 Over the weekend I picked up a display board that appears to have come
 from a clock or time code device.  It has four Panaplex display modules
 and a single LED.  The board is silkscreened with a LN logo and
 appears to be circa 1974 (if what looks like a date code is actually a
 date code).
 
 I have pictures up at
 http://www.decodesystems.com/help-wanted/index.html#panaplex.  Does
 anyone recognize the logo and/or the device this board might have come from?
 
 
 Thanks,
 Dan
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[time-nuts] Help identifying a display board

[Gordon Batey]

Dan

That might possibly be Leeds  Northrup???

73 Gordon WA4FJC

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Re: [time-nuts] Help understanding an ADEV

[Hal Murray]

b...@evoria.net said:
 Note: The DAC module is designed specifically for audio applications and is
 not recommended for control type applications.

 I had hoped that it wouldn't be a problem for driving an OCXO, but my
 mistake.  The datasheet also notes that the DAC has 16-bit resolution but
 only 14-bit accuracy.  It didn't seem to have even that at DC.  The PWM
 version doesn't have any escape clauses.  You set x parameters and it's
 supposed to be 16-bits wide.  Maybe audio means within the human auditory
 passband? 

In the old days, the specs for DACs and ADCs were easy to understand, at 
least after you figured things out, and all the major vendors had app-notes 
explaining what the parameters meant.  There was INL, DNL and a few buzzwords 
like no-missing-codes and monotonic.

Ballpark of 20 years ago, things got much more complicated.  A new generation 
of chips came out targeted at DSP applications.  FFT plots started appearing 
in data sheets.  Parameters like ENOB (effective number of bits) became the 
important ones.

On top of that, if you are interested in audio or radar, temperature 
stability is not an important parameter.



-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Help understanding an ADEV

[Bob Stewart]

Hi Andrew,

Yeah, it was a pretty dumb mistake, but I think I learned my lesson.  At the 
very least, my scripts now allow me to skip as many initial samples as I like 
before the data is plotted.

And, the PWM version of the chip is in.  It's orders of magnitude more stable 
than the audio DAC in the one I've been posting about.  So, I'm doing testing 
and tuning, and will be back with still more questions.  But, I'm finally 
starting to get reasonable results.


Bob - AE6RV



 From: Andrew Rodland and...@cleverdomain.org
To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency 
measurement time-nuts@febo.com 
Cc: Tom Van Baak t...@leapsecond.com 
Sent: Friday, September 12, 2014 4:29 PM
Subject: Re: [time-nuts] Help understanding an ADEV
 

Your intuition isn't completely wrong -- the law of averages still
applies. As you provide more and more good data it will eventually
overwhelm the initial bad data, and the result will get closer to
correct.

But it will take a *lot* of data to overwhelm even a few data points
that have a deviation a hundred thousand times as large as the
deviation you're trying to measure. You would probably have to run for
months before you could trust the plot out to tau = 1s. Removing
the bad data is a superior alternative, if you ask me :)

Andrew




On Thu, Sep 11, 2014 at 5:21 PM, Bob Stewart b...@evoria.net wrote:
 Hi Tom,

 And thank you very much for taking the time to look at this.  No, I don't 
 know what the heck a lot of this means, and it's no surprise that I used the 
 wrong tool.  I had noticed the first few seconds of bad data, but didn't 
 think it would matter over long sample sessions.

 I'll take some time to get this together properly and see what I can find 
 out.  The new PIC arrives tomorrow, so I'll know pretty quickly if there is a 
 big improvement in the noise.

 Thank you again, and everyone else who has taken even a moment of time to 
 help me during this project!


 Bob



 
  From: Tom Van Baak t...@leapsecond.com
 To: Discussion of precise time and frequency measurement time-nuts@febo.com
 Sent: Thursday, September 11, 2014 3:53 PM
 Subject: Re: [time-nuts] Help understanding an ADEV


 I've been wondering if it would be better to look in the frequency domain.
 I'll have to look at Tom's site to see if he has code to do that.
 Bob

 Hi Bob,

 Ok, I think I found the problem with your plot. There's one mistake, one 
 misunderstanding, and a miscalibration.


 1) It appears you're allowing bogus DAC readings to pollute the ADEV 
 calculation. Based on the raw data you kindly sent, your nominal DAC value is 
 about 2.1 volts and your DAC voltage typically changes by tens or low 
 hundreds of microvolts.

 However the first couple of data points are 0.0 and 1.0 volts. The ADEV 
 calculation is therefore seeing changes of millions (!) of microvolts. This 
 completely messes up every ADEV calculation at every tau of your plot. You 
 must feed clean data into any ADEV calculation. Either fix your 
 instrumentation, or put checks in your scripts, or visually examine time 
 series data before you blindly feed it into a statistical formula or a tool.

 I don't know why the plotting package you used does not show these points. 
 Those four bogus points should have been an instant red flag.


 2) Realize that we normally make ADEV plots only from phase data or from 
 frequency data. Phase data is the net time difference (or time interval) 
 between the DUT and the REF. Units are seconds. Frequency data is the 
 (normalized) relative frequency difference between the DUT and the REF. This 
 is unitless.

 Now in your case, you want to make an ADEV plot from DAC data. This is ok, 
 since DAC voltage is essentially a proxy for frequency offset. But you can't 
 feed DAC or frequency data into the adev1 tool, since that tool expects phase 
 data only. Make sense?

 The details are that ADEV is based on the 2nd difference in phase, which is 
 the 1st difference in frequency. You have accidentally feed frequency data 
 into a phase calculation and the result is some sort of 3rd difference! This 
 is not what you want.

 The solution is either to integrate your DAC or frequency data so it looks 
 like phase. Or, just use a tool that will take frequency data instead of 
 phase data. Stable32 and TimeLab offer this option. Or you can use adev1f.exe 
 (www.leapsecond.com/tools/) which I just made for you.


 3) To get an accurate ADEV plot you must scale your arbitrary DAC voltage to 
 real Hz. Use the known or measured EFC offset and gain to convert absolute 
 voltage to relative voltage to relative frequency error. This data can then 
 be given to Stable32 (Data Type: Freq), or TimeLab (File data: Frequency 
 difference), or feed directly to the new tool, adev1f.

 Let me know if you have any questions.

 /tvb


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Re: [time-nuts] Help understanding an ADEV

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 11 Sep 2014 04:35, Bob Stewart b...@evoria.net wrote:

 I've ordered the PWM version of the PIC, and hopefully, since it's the
motor control version (as opposed to the audio version) it will have much
better noise performance.

I don't know the PIC but I would have thought chips for audio would be
optimised for low noise far less than one for driving motors.

Dr David Kirkby
Managing Director
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3
6DT, United Kingdom
Registered in England and Wales as company number 08914892
http://www.kirkbymicrowave.co.uk/
Tel 07910 441670 / +44 7910 441670 (0900-2100 GMT)
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Re: [time-nuts] Help understanding an ADEV

[Dr. David Kirkby (Kirkby Microwave Ltd)]

OOPS! CORRECTION.

I don't know the PIC but I would have thought chips for audio would be
optimised for low noise far MOOR than one for driving motors.

Ears are more sensitive to a bit of noise than motors.

I assume I have misunderstood you.

Dave
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Re: [time-nuts] Help understanding an ADEV

[Bob Stewart]

Hi David,


It's an odd situation.  From the datasheet:

Note: The DAC module is designed specifically for audio applications and is 
not recommended for control type applications.

I had hoped that it wouldn't be a problem for driving an OCXO, but my mistake.  
The datasheet also notes that the DAC has 16-bit resolution but only 14-bit 
accuracy.  It didn't seem to have even that at DC.  The PWM version doesn't 
have any escape clauses.  You set x parameters and it's supposed to be 
16-bits wide.  Maybe audio means within the human auditory passband?


Bob




 From: Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk
To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency 
measurement time-nuts@febo.com 
Sent: Saturday, September 13, 2014 4:27 PM
Subject: Re: [time-nuts] Help understanding an ADEV
 





On 11 Sep 2014 04:35, Bob Stewart b...@evoria.net wrote:
 I've ordered the PWM version of the PIC, and hopefully, since it's the motor 
 control version (as opposed to the audio version) it will have much better 
 noise performance.
I don't know the PIC but I would have thought chips for audio would be 
optimised for low noise far less than one for driving motors.
Dr David Kirkby
Managing Director
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Chelmsford, Essex, CM3 6DT, 
United Kingdom
Registered in England and Wales as company number 08914892
http://www.kirkbymicrowave.co.uk/
Tel 07910 441670 / +44 7910 441670 (0900-2100 GMT)
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Re: [time-nuts] Help understanding an ADEV

[Andrew Rodland]

Your intuition isn't completely wrong -- the law of averages still
applies. As you provide more and more good data it will eventually
overwhelm the initial bad data, and the result will get closer to
correct.

But it will take a *lot* of data to overwhelm even a few data points
that have a deviation a hundred thousand times as large as the
deviation you're trying to measure. You would probably have to run for
months before you could trust the plot out to tau = 1s. Removing
the bad data is a superior alternative, if you ask me :)

Andrew

On Thu, Sep 11, 2014 at 5:21 PM, Bob Stewart b...@evoria.net wrote:
 Hi Tom,

 And thank you very much for taking the time to look at this.  No, I don't 
 know what the heck a lot of this means, and it's no surprise that I used the 
 wrong tool.  I had noticed the first few seconds of bad data, but didn't 
 think it would matter over long sample sessions.

 I'll take some time to get this together properly and see what I can find 
 out.  The new PIC arrives tomorrow, so I'll know pretty quickly if there is a 
 big improvement in the noise.

 Thank you again, and everyone else who has taken even a moment of time to 
 help me during this project!


 Bob



 
  From: Tom Van Baak t...@leapsecond.com
 To: Discussion of precise time and frequency measurement time-nuts@febo.com
 Sent: Thursday, September 11, 2014 3:53 PM
 Subject: Re: [time-nuts] Help understanding an ADEV


 I've been wondering if it would be better to look in the frequency domain.
 I'll have to look at Tom's site to see if he has code to do that.
 Bob

 Hi Bob,

 Ok, I think I found the problem with your plot. There's one mistake, one 
 misunderstanding, and a miscalibration.


 1) It appears you're allowing bogus DAC readings to pollute the ADEV 
 calculation. Based on the raw data you kindly sent, your nominal DAC value is 
 about 2.1 volts and your DAC voltage typically changes by tens or low 
 hundreds of microvolts.

 However the first couple of data points are 0.0 and 1.0 volts. The ADEV 
 calculation is therefore seeing changes of millions (!) of microvolts. This 
 completely messes up every ADEV calculation at every tau of your plot. You 
 must feed clean data into any ADEV calculation. Either fix your 
 instrumentation, or put checks in your scripts, or visually examine time 
 series data before you blindly feed it into a statistical formula or a tool.

 I don't know why the plotting package you used does not show these points. 
 Those four bogus points should have been an instant red flag.


 2) Realize that we normally make ADEV plots only from phase data or from 
 frequency data. Phase data is the net time difference (or time interval) 
 between the DUT and the REF. Units are seconds. Frequency data is the 
 (normalized) relative frequency difference between the DUT and the REF. This 
 is unitless.

 Now in your case, you want to make an ADEV plot from DAC data. This is ok, 
 since DAC voltage is essentially a proxy for frequency offset. But you can't 
 feed DAC or frequency data into the adev1 tool, since that tool expects phase 
 data only. Make sense?

 The details are that ADEV is based on the 2nd difference in phase, which is 
 the 1st difference in frequency. You have accidentally feed frequency data 
 into a phase calculation and the result is some sort of 3rd difference! This 
 is not what you want.

 The solution is either to integrate your DAC or frequency data so it looks 
 like phase. Or, just use a tool that will take frequency data instead of 
 phase data. Stable32 and TimeLab offer this option. Or you can use adev1f.exe 
 (www.leapsecond.com/tools/) which I just made for you.


 3) To get an accurate ADEV plot you must scale your arbitrary DAC voltage to 
 real Hz. Use the known or measured EFC offset and gain to convert absolute 
 voltage to relative voltage to relative frequency error. This data can then 
 be given to Stable32 (Data Type: Freq), or TimeLab (File data: Frequency 
 difference), or feed directly to the new tool, adev1f.

 Let me know if you have any questions.

 /tvb


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Re: [time-nuts] Help understanding an ADEV

[Bob Camp]

Hi

The plot pretty much confirms what you already know - there is a noise spectrum 
and it’s not what you want to have. In a closed loop system, it’s all going to 
add up. The big unknown is - do you get noise out of the DAC trying to correct 
the OCXO’s noise or just noise out of the DAC? Is the DAC noise from the DAC 
it’s self or from the loop?

One source of noise is the LSB on the DAC. If you have a 1 ppm EFC and a 
1x10^-12 OCXO and a 1 LSB change at 1 second (yes that’s a lot …) - That’s a 
1x10^6 delta, you must have a ~20 bit DAC. If you have 1x10^-8 out of your GPS, 
 your loop (or filter) must have a 10,000:1 attenuation at 1 Hz. That’s 80 db. 
If you have a simple loop, you get 20 db / decade. That would put your tau 
below 0.0001 Hz.

Yes those are fast and simple numbers. The real stuff has a lot more if’s and’s 
and but’s in it.  

Simple way to check things:

1) Do an ADEV on the OCXO + EFC and make sure it looks right outside the loop.
2) Do an ADEV on your GPS and figure out where it’s at. 
3) Consider checking the noise in the frequency domain, it’s easier to 
understand.

So much fun.

Bob

On Sep 10, 2014, at 11:06 PM, Bob Stewart b...@evoria.net wrote:

 After spending a lot of effort trying to get some useful tuning figures for 
 the PID in my GPSDO engine, I decided to capture the DAC output with my 
 3456A.  And, of course I've made an ADEV plot.  If I understand this 
 correctly, it means that there is mostly justnoise out to 2 tau, and an area 
 from about 4-5 tau is mostly noise, as well.  Could someone tell me if I have 
 this right?  It matches what I'm seeing on the delta plot, and would explain 
 why we couldn't get anything approaching reasonable stability from the OCXO, 
 since the noise is larger than the increments being made to the DAC.
 
 
 I've ordered the PWM version of the PIC, and hopefully, since it's the motor 
 control version (as opposed to the audio version) it will have much better 
 noise performance.
 
 The red scatter is the EFC measured at the OCXO in tens of microvolts, and 
 the blue line is the ADEV.  I'm using a short shielded twisted-pair with 
 mini-clipsas the probe.  Hopefully I've got things scaled properly and have 
 run the test properly.
 
 
 http://evoria.net/AE6RV/TIC/DAC.wander.png
 
 Bob - AE6RV
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Re: [time-nuts] Help understanding an ADEV

[Tom Van Baak]

Hi Bob S,

Since you're using DAC voltage as an input, did you calculate ADEV using the 
y equation (single difference) instead of the usual x equation (double 
difference)?

Looking at the red dots, there is significant measurement quantization (1 unit, 
or 10 uV) and a massive amount of noise (close to 50 units, half a millivolt). 
Is this due to your voltmeter, your measurement setup, or is the DAC really 
that terrible?

In your case, an ADEV plot made from a phase or frequency measurement should 
match an ADEV plot made from a DAC measurement. However, the fidelity of the 
plot is highly dependent on the resolution of the instrument being used. 
Typically you choose between a phase meter, frequency counter, or voltmeter by 
which one gives you the best resolution. Otherwise your ADEV plot is just 
showing the limitations of your instrument, not the GPSDO that you're trying to 
measure.

/tvb

- Original Message - 
From: Bob Stewart b...@evoria.net
To: Time Nuts time-nuts@febo.com
Sent: Wednesday, September 10, 2014 8:06 PM
Subject: [time-nuts] Help understanding an ADEV


 After spending a lot of effort trying to get some useful tuning figures for 
 the PID in my GPSDO engine, I decided to capture the DAC output with my 
 3456A.  And, of course I've made an ADEV plot.  If I understand this 
 correctly, it means that there is mostly justnoise out to 2 tau, and an area 
 from about 4-5 tau is mostly noise, as well.  Could someone tell me if I have 
 this right?  It matches what I'm seeing on the delta plot, and would explain 
 why we couldn't get anything approaching reasonable stability from the OCXO, 
 since the noise is larger than the increments being made to the DAC.
 
 
 I've ordered the PWM version of the PIC, and hopefully, since it's the motor 
 control version (as opposed to the audio version) it will have much better 
 noise performance.
 
 The red scatter is the EFC measured at the OCXO in tens of microvolts, and 
 the blue line is the ADEV.  I'm using a short shielded twisted-pair with 
 mini-clipsas the probe.  Hopefully I've got things scaled properly and have 
 run the test properly.
 
 
 http://evoria.net/AE6RV/TIC/DAC.wander.png
 
 Bob - AE6RV


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Re: [time-nuts] Help understanding an ADEV

[Bob Stewart]

Hi Bob,

After I posted last night, I realized that the loop was running, so I froze 
the DAC and did another sample.  Here is the voltage plot in 10s of uV, 
as well as the ADEV.  I can pull the op-amp out of the GSPDO engine and 
plot it without the DAC attached if that would be helpful.  There is a 
voltage-divider at the OCXO attached to the VRef output from the OCXO.  As 
always, I use Tom's adev1 software.


http://evoria.net/AE6RV/TIC/DAC.wander.2.png

I don't understand what you are asking for to do an ADEV of the GPS.  What do I 
plot and under what conditions?

I've been wondering if it would be better to look in the frequency domain.  
I'll have to look at Tom's site to see if he has code to do that.
Bob



 From: Bob Camp kb...@n1k.org
To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency 
measurement time-nuts@febo.com 
Sent: Thursday, September 11, 2014 6:10 AM
Subject: Re: [time-nuts] Help understanding an ADEV
 

Hi

The plot pretty much confirms what you already know - there is a noise spectrum 
and it’s not what you want to have. In a closed loop system, it’s all going to 
add up. The big unknown is - do you get noise out of the DAC trying to correct 
the OCXO’s noise or just noise out of the DAC? Is the DAC noise from the DAC 
it’s self or from the loop?

One source of noise is the LSB on the DAC. If you have a 1 ppm EFC and a 
1x10^-12 OCXO and a 1 LSB change at 1 second (yes that’s a lot …) - That’s a 
1x10^6 delta, you must have a ~20 bit DAC. If you have 1x10^-8 out of your GPS, 
 your loop (or filter) must have a 10,000:1 attenuation at 1 Hz. That’s 80 db. 
If you have a simple loop, you get 20 db / decade. That would put your tau 
below 0.0001 Hz.

Yes those are fast and simple numbers. The real stuff has a lot more if’s and’s 
and but’s in it.  

Simple way to check things:

1) Do an ADEV on the OCXO + EFC and make sure it looks right outside the loop.
2) Do an ADEV on your GPS and figure out where it’s at. 
3) Consider checking the noise in the frequency domain, it’s easier to 
understand.

So much fun.

Bob


On Sep 10, 2014, at 11:06 PM, Bob Stewart b...@evoria.net wrote:

 After spending a lot of effort trying to get some useful tuning figures for 
 the PID in my GPSDO engine, I decided to capture the DAC output with my 
 3456A.  And, of course I've made an ADEV plot.  If I understand this 
 correctly, it means that there is mostly justnoise out to 2 tau, and an area 
 from about 4-5 tau is mostly noise, as well.  Could someone tell me if I have 
 this right?  It matches what I'm seeing on the delta plot, and would explain 
 why we couldn't get anything approaching reasonable stability from the OCXO, 
 since the noise is larger than the increments being made to the DAC.
 
 
 I've ordered the PWM version of the PIC, and hopefully, since it's the motor 
 control version (as opposed to the audio version) it will have much better 
 noise performance.
 
 The red scatter is the EFC measured at the OCXO in tens of microvolts, and 
 the blue line is the ADEV.  I'm using a short shielded twisted-pair with 
 mini-clipsas the probe.  Hopefully I've got things scaled properly and have 
 run the test properly.
 
 
 http://evoria.net/AE6RV/TIC/DAC.wander.png
 
 Bob - AE6RV
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Re: [time-nuts] Help understanding an ADEV

[Bob Stewart]

Here are a couple of reference plots.  The only thing really important is the 
voltage trace in red.  It's in 10s of microvolts.

The first one is just measuring the EFC at the OCXO which is only being driven 
by the VRef output of the OCXO.  I think it clears the 3456A of any wrongdoing.

http://evoria.net/AE6RV/TIC/VRef.vs.3456A.png

The second one tests the noise from the op-amp by supplying its input with 3.3V 
from the PIC's VDD.  The PIC's DAC output is disconnected for this plot.  
There's a few more tens of microvolts of noise than in the one above, but 
that's to be expected, I think.  It's certainly nowhere near the noise on the 
other two plots driven by the DAC.


http://evoria.net/AE6RV/TIC/Op-Amp.png

Bob






 From: Bob Stewart b...@evoria.net
To: Time Nuts time-nuts@febo.com 
Sent: Wednesday, September 10, 2014 10:06 PM
Subject: [time-nuts] Help understanding an ADEV
 

After spending a lot of effort trying to get some useful tuning figures for the 
PID in my GPSDO engine, I decided to capture the DAC output with my 3456A.  
And, of course I've made an ADEV plot.  If I understand this correctly, it 
means that there is mostly justnoise out to 2 tau, and an area from about 4-5 
tau is mostly noise, as well.  Could someone tell me if I have this right?  It 
matches what I'm seeing on the delta plot, and would explain why we couldn't 
get anything approaching reasonable stability from the OCXO, since the noise is 
larger than the increments being made to the DAC.


I've ordered the PWM version of the PIC, and hopefully, since it's the motor 
control version (as opposed to the audio version) it will have much better 
noise performance.

The red scatter is the EFC measured at the OCXO in tens of microvolts, and the 
blue line is the ADEV.  I'm using a short shielded twisted-pair with 
mini-clipsas the probe.  Hopefully I've got things scaled properly and have run 
the test properly.


http://evoria.net/AE6RV/TIC/DAC.wander.png

Bob - AE6RV
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Re: [time-nuts] Help understanding an ADEV

[Tom Van Baak]

 I've been wondering if it would be better to look in the frequency domain.  
 I'll have to look at Tom's site to see if he has code to do that.
 Bob

Hi Bob,

Ok, I think I found the problem with your plot. There's one mistake, one 
misunderstanding, and a miscalibration.


1) It appears you're allowing bogus DAC readings to pollute the ADEV 
calculation. Based on the raw data you kindly sent, your nominal DAC value is 
about 2.1 volts and your DAC voltage typically changes by tens or low hundreds 
of microvolts.

However the first couple of data points are 0.0 and 1.0 volts. The ADEV 
calculation is therefore seeing changes of millions (!) of microvolts. This 
completely messes up every ADEV calculation at every tau of your plot. You must 
feed clean data into any ADEV calculation. Either fix your instrumentation, or 
put checks in your scripts, or visually examine time series data before you 
blindly feed it into a statistical formula or a tool.

I don't know why the plotting package you used does not show these points. 
Those four bogus points should have been an instant red flag.


2) Realize that we normally make ADEV plots only from phase data or from 
frequency data. Phase data is the net time difference (or time interval) 
between the DUT and the REF. Units are seconds. Frequency data is the 
(normalized) relative frequency difference between the DUT and the REF. This is 
unitless.

Now in your case, you want to make an ADEV plot from DAC data. This is ok, 
since DAC voltage is essentially a proxy for frequency offset. But you can't 
feed DAC or frequency data into the adev1 tool, since that tool expects phase 
data only. Make sense?

The details are that ADEV is based on the 2nd difference in phase, which is the 
1st difference in frequency. You have accidentally feed frequency data into a 
phase calculation and the result is some sort of 3rd difference! This is not 
what you want.

The solution is either to integrate your DAC or frequency data so it looks like 
phase. Or, just use a tool that will take frequency data instead of phase data. 
Stable32 and TimeLab offer this option. Or you can use adev1f.exe 
(www.leapsecond.com/tools/) which I just made for you.


3) To get an accurate ADEV plot you must scale your arbitrary DAC voltage to 
real Hz. Use the known or measured EFC offset and gain to convert absolute 
voltage to relative voltage to relative frequency error. This data can then be 
given to Stable32 (Data Type: Freq), or TimeLab (File data: Frequency 
difference), or feed directly to the new tool, adev1f.

Let me know if you have any questions.

/tvb


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Re: [time-nuts] Help understanding an ADEV

[Bob Stewart]

Hi Tom,

And thank you very much for taking the time to look at this.  No, I don't know 
what the heck a lot of this means, and it's no surprise that I used the wrong 
tool.  I had noticed the first few seconds of bad data, but didn't think it 
would matter over long sample sessions.  

I'll take some time to get this together properly and see what I can find out.  
The new PIC arrives tomorrow, so I'll know pretty quickly if there is a big 
improvement in the noise.

Thank you again, and everyone else who has taken even a moment of time to help 
me during this project!


Bob




 From: Tom Van Baak t...@leapsecond.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com 
Sent: Thursday, September 11, 2014 3:53 PM
Subject: Re: [time-nuts] Help understanding an ADEV
 

 I've been wondering if it would be better to look in the frequency domain.  
 I'll have to look at Tom's site to see if he has code to do that.
 Bob

Hi Bob,

Ok, I think I found the problem with your plot. There's one mistake, one 
misunderstanding, and a miscalibration.


1) It appears you're allowing bogus DAC readings to pollute the ADEV 
calculation. Based on the raw data you kindly sent, your nominal DAC value is 
about 2.1 volts and your DAC voltage typically changes by tens or low hundreds 
of microvolts.

However the first couple of data points are 0.0 and 1.0 volts. The ADEV 
calculation is therefore seeing changes of millions (!) of microvolts. This 
completely messes up every ADEV calculation at every tau of your plot. You must 
feed clean data into any ADEV calculation. Either fix your instrumentation, or 
put checks in your scripts, or visually examine time series data before you 
blindly feed it into a statistical formula or a tool.

I don't know why the plotting package you used does not show these points. 
Those four bogus points should have been an instant red flag.


2) Realize that we normally make ADEV plots only from phase data or from 
frequency data. Phase data is the net time difference (or time interval) 
between the DUT and the REF. Units are seconds. Frequency data is the 
(normalized) relative frequency difference between the DUT and the REF. This is 
unitless.

Now in your case, you want to make an ADEV plot from DAC data. This is ok, 
since DAC voltage is essentially a proxy for frequency offset. But you can't 
feed DAC or frequency data into the adev1 tool, since that tool expects phase 
data only. Make sense?

The details are that ADEV is based on the 2nd difference in phase, which is the 
1st difference in frequency. You have accidentally feed frequency data into a 
phase calculation and the result is some sort of 3rd difference! This is not 
what you want.

The solution is either to integrate your DAC or frequency data so it looks like 
phase. Or, just use a tool that will take frequency data instead of phase data. 
Stable32 and TimeLab offer this option. Or you can use adev1f.exe 
(www.leapsecond.com/tools/) which I just made for you.


3) To get an accurate ADEV plot you must scale your arbitrary DAC voltage to 
real Hz. Use the known or measured EFC offset and gain to convert absolute 
voltage to relative voltage to relative frequency error. This data can then be 
given to Stable32 (Data Type: Freq), or TimeLab (File data: Frequency 
difference), or feed directly to the new tool, adev1f.

Let me know if you have any questions.

/tvb


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[time-nuts] Help understanding an ADEV

[Bob Stewart]

After spending a lot of effort trying to get some useful tuning figures for the 
PID in my GPSDO engine, I decided to capture the DAC output with my 3456A.  
And, of course I've made an ADEV plot.  If I understand this correctly, it 
means that there is mostly justnoise out to 2 tau, and an area from about 4-5 
tau is mostly noise, as well.  Could someone tell me if I have this right?  It 
matches what I'm seeing on the delta plot, and would explain why we couldn't 
get anything approaching reasonable stability from the OCXO, since the noise is 
larger than the increments being made to the DAC.


I've ordered the PWM version of the PIC, and hopefully, since it's the motor 
control version (as opposed to the audio version) it will have much better 
noise performance.

The red scatter is the EFC measured at the OCXO in tens of microvolts, and the 
blue line is the ADEV.  I'm using a short shielded twisted-pair with 
mini-clipsas the probe.  Hopefully I've got things scaled properly and have run 
the test properly.


http://evoria.net/AE6RV/TIC/DAC.wander.png

Bob - AE6RV
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[time-nuts] help me understand AM noise

[life speed]

Hi Guys.  It has been a while since I posted, hope you can help with a slightly 
time-related topic.  Can't have frequency without amplitude . . .

I recently designed an Automatic Level Control circuit consisting of dual-slope 
detector logger, open and closed loop references with AM modulation, and a 
linearizer (volts/dB) driver for series/shunt microwave attenuators.  This is 
part of a DC - 20 GHz microwave synthesizer.  I measured the AM noise at 3 GHz, 
both open and closed loop, and find the noise level is higher at the output of 
the attenuator/amplifier chain at similar power levels to the input (13 dBm).  
The input RF chain saturates at about 17 dBm, while the output amp following 
the attenuators saturates at about 20 dBm.

I understand that an amplifier in compression will suppress AM noise.  What I 
wonder is are my measurements of increased AM noise (red trace) at the output 
of the attenuator/amp lineup to be expected based on the higher available 
saturated power?  Is it possible to attenuate the signal using the power 
control (open loop in this example, ALC is not used) without degrading AM noise 
performance?  Does anybody have any suggested reading on this subject?  I am 
trying to understand how well my circuit performs, in general.  I do observe 
that control the power to a lower  level increases the AM noise.  But it is a 
relative measurement to begin with, so what is good?  I have been reading the 
Agilent E5500 user guide on AM noise measurements, but don't find a great deal 
of information there regarding AM noise performance of a Device Under Test.

Thanks,

Lifespeed

http://home.comcast.net/~claybu/pics/electronics/am_noise_1.png

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[time-nuts] Help OCXO ID

[Francesco Messineo]

Hello all,

does anyone know what's the OCXO (or else) in this picture?

http://www.electronicsurplus.it/open2b/var/catalog/images/1354/0-c26b2bc0-800.jpg

I'm trying to understand if it's something worth buying, but I can't
find any information on the site other than 5 MHz oven quartz
oscillator (and I'm not sure they exactly know even that).

Thanks in advance.

Frank IZ8DWF
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Re: [time-nuts] Help for general GPIB problem

[Ulrich Bangert]

John,

thank you for your help. The idea to use IBDEV resulted from the following
official NI statement:

Snip

For current and new GPIB applications, IBDEV should be used. IBFIND will
return a board or device descriptor based off the device templates in the
GPIB.ini file. Since IBFIND relies on GPIB.ini to return the board or device
descriptor, it is difficult to port. For example, with the device templates,
the device name can be changed to a custom name. Unless the device templates
are ported to the target machine, the call will fail. IBFIND is found in
older applications and can be easily updated to using IBDEV instead.

IBDEV is far more portable in that it frees the application from the need to
rely on specific device names. IBDEV also returns a board or device
descriptor but allows you to programmatically specify all the required input
parameters in the parameter list of IBDEV (thus avoiding the need to refer
to device templates). IBDEV should be used when creating a new GPIB device
application.

IBFIND should still be used to open a GPIB board communication session, not
for communication with instruments.

Snip---

But i will of course follow your suggestion to look up Timelab's enumeration
function.

73's de Ulrich, DF6JB 

 -Ursprungliche Nachricht-
 Von: time-nuts-boun...@febo.com 
 [mailto:time-nuts-boun...@febo.com] Im Auftrag von John Miles
 Gesendet: Freitag, 24. Januar 2014 08:58
 An: 'Discussion of precise time and frequency measurement'
 Betreff: Re: [time-nuts] Help for general GPIB problem
 
 
 You probably want ibfind() rather than ibdev().  Take a look 
 at gpibport.cpp in the TimeLab source 
 (drivers/shared/gpibport.cpp under the installation folder), 
 in the enumerate_ports() function.  
 
 -- john, KE5FX
 Miles Design LLC
 
  -Original Message-
  From: time-nuts-boun...@febo.com [mailto:time-nuts- 
 boun...@febo.com] 
  On Behalf Of Ulrich Bangert
  Sent: Thursday, January 23, 2014 3:23 AM
  To: Time nuts
  Subject: [time-nuts] Help for general GPIB problem
  
  Gentlemen,
  
  I am just going to improve my EZGPIB utility so that it can 
 make use 
  of
 more
  than one GPIB-interface (supported by GPIB32.Dll, not Prologix). I 
  have been trying to enumerate all detected interfaces by using
  
  ibdev(bi,0,0,T300ms,0,1)
  
  in a loop where bi starts with 0 and is incremented by 
 1 until the 
  result of the call gets negative. Much to my surprise this loop 
  detects 4
  (!) interfaces GPIB0 to GPIB3 even if absolutely NO 
 interface is connected
  to the pc.
  
  What am I doing wrong. Is 4 the maximum number of interfaces that 
  may be handled by GPIB32.Dll 
  
  What do I need to do to find the real number of detected interfaces 
  ?
  
  Best regards and TIA for your answers
  
  Ulrich Bangert
  www.ulrich-bangert.de
  Ortholzer Weg 1
  27243 Gross Ippener
  
  ___
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Re: [time-nuts] Help for general GPIB problem

[John Miles]

Hmm, yes, it's tough to say what might have motivated that recommendation.
I have no idea what a device template is, or what it might mean for
ibfind() to be difficult to port.  It's worked for many years here, with
both genuine and emulated (HP 82350-series) adapters.

The one issue I've experienced is the inability of 64-bit Windows apps to
detect the emulated NI488.2 devices provided by Agilent I/O Libraries for
the 82357 adapters.  This is why the 32-bit drivers are still linked with
gpib-32.obj rather than the newer ni4882.obj API module.  
 
-- john, KE5FX
Miles Design LLC


 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-
 boun...@febo.com] On Behalf Of Ulrich Bangert
 Sent: Friday, January 24, 2014 1:29 AM
 To: 'Discussion of precise time and frequency measurement'
 Subject: Re: [time-nuts] Help for general GPIB problem
 
 John,
 
 thank you for your help. The idea to use IBDEV resulted from the following
 official NI statement:
 
 Snip
 
 For current and new GPIB applications, IBDEV should be used. IBFIND will
 return a board or device descriptor based off the device templates in the
 GPIB.ini file. Since IBFIND relies on GPIB.ini to return the board or
device
 descriptor, it is difficult to port. For example, with the device
templates,
 the device name can be changed to a custom name. Unless the device
 templates
 are ported to the target machine, the call will fail. IBFIND is found in
 older applications and can be easily updated to using IBDEV instead.
 
 IBDEV is far more portable in that it frees the application from the need
to
 rely on specific device names. IBDEV also returns a board or device
 descriptor but allows you to programmatically specify all the required
input
 parameters in the parameter list of IBDEV (thus avoiding the need to refer
 to device templates). IBDEV should be used when creating a new GPIB
 device
 application.
 
 IBFIND should still be used to open a GPIB board communication session,
 not
 for communication with instruments.
 
 Snip---
 
 But i will of course follow your suggestion to look up Timelab's
enumeration
 function.
 
 73's de Ulrich, DF6JB
 
  -Ursprungliche Nachricht-
  Von: time-nuts-boun...@febo.com
  [mailto:time-nuts-boun...@febo.com] Im Auftrag von John Miles
  Gesendet: Freitag, 24. Januar 2014 08:58
  An: 'Discussion of precise time and frequency measurement'
  Betreff: Re: [time-nuts] Help for general GPIB problem
 
 
  You probably want ibfind() rather than ibdev().  Take a look
  at gpibport.cpp in the TimeLab source
  (drivers/shared/gpibport.cpp under the installation folder),
  in the enumerate_ports() function.
 
  -- john, KE5FX
  Miles Design LLC
 
   -Original Message-
   From: time-nuts-boun...@febo.com [mailto:time-nuts-
  boun...@febo.com]
   On Behalf Of Ulrich Bangert
   Sent: Thursday, January 23, 2014 3:23 AM
   To: Time nuts
   Subject: [time-nuts] Help for general GPIB problem
  
   Gentlemen,
  
   I am just going to improve my EZGPIB utility so that it can
  make use
   of
  more
   than one GPIB-interface (supported by GPIB32.Dll, not Prologix). I
   have been trying to enumerate all detected interfaces by using
  
   ibdev(bi,0,0,T300ms,0,1)
  
   in a loop where bi starts with 0 and is incremented by
  1 until the
   result of the call gets negative. Much to my surprise this loop
   detects 4
   (!) interfaces GPIB0 to GPIB3 even if absolutely NO
  interface is connected
   to the pc.
  
   What am I doing wrong. Is 4 the maximum number of interfaces that
   may be handled by GPIB32.Dll 
  
   What do I need to do to find the real number of detected interfaces
   ?
  
   Best regards and TIA for your answers
  
   Ulrich Bangert
   www.ulrich-bangert.de
   Ortholzer Weg 1
   27243 Gross Ippener
  
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[time-nuts] Help for general GPIB problem

[Ulrich Bangert]

Gentlemen,

I am just going to improve my EZGPIB utility so that it can make use of more
than one GPIB-interface (supported by GPIB32.Dll, not Prologix). I have been
trying to enumerate all detected interfaces by using

ibdev(bi,0,0,T300ms,0,1)

in a loop where bi starts with 0 and is incremented by 1 until the
result of the call gets negative. Much to my surprise this loop detects 4
(!) interfaces GPIB0 to GPIB3 even if absolutely NO interface is connected
to the pc. 

What am I doing wrong. Is 4 the maximum number of interfaces that may be
handled by GPIB32.Dll 

What do I need to do to find the real number of detected interfaces ?

Best regards and TIA for your answers

Ulrich Bangert
www.ulrich-bangert.de
Ortholzer Weg 1
27243 Gross Ippener 

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Re: [time-nuts] Help for general GPIB problem

[Azelio Boriani]

Try to stop the HPIB driver... maybe the driver is reporting as
available even if no hardware is actually connected.

On Thu, Jan 23, 2014 at 12:22 PM, Ulrich Bangert
df...@ulrich-bangert.de wrote:
 Gentlemen,

 I am just going to improve my EZGPIB utility so that it can make use of more
 than one GPIB-interface (supported by GPIB32.Dll, not Prologix). I have been
 trying to enumerate all detected interfaces by using

 ibdev(bi,0,0,T300ms,0,1)

 in a loop where bi starts with 0 and is incremented by 1 until the
 result of the call gets negative. Much to my surprise this loop detects 4
 (!) interfaces GPIB0 to GPIB3 even if absolutely NO interface is connected
 to the pc.

 What am I doing wrong. Is 4 the maximum number of interfaces that may be
 handled by GPIB32.Dll 

 What do I need to do to find the real number of detected interfaces ?

 Best regards and TIA for your answers

 Ulrich Bangert
 www.ulrich-bangert.de
 Ortholzer Weg 1
 27243 Gross Ippener

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Re: [time-nuts] Help for general GPIB problem

[Ulrich Bangert]

Azelio,

 Try to stop the HPIB driver...

I do not have any HPIB (=HP specific) driver in my system. Instead I use the
GPIB32.DLL that comes together with every National Instruments GPIB
interface adapter. The DLL is basically thought as the National Instruments
support for C-Programmers but I wrote a wrapper unit to be able to use the
DLL from my Delphi programming environment.  

The DLL is the BASIC translation between software and hardware and can
hardly been left away. It is responsible for the fact that you can use the
same DLL function calls regardless of what physical interface is used, i.e.
it works with a PCI plugin card as well as with USB to GPIB adapters as well
as with network based GPIB adapters (as long as the all come from NI). That
is one of the really NEAT things with NI stuff.

Best regards
Ulrich 



 -Ursprungliche Nachricht-
 Von: time-nuts-boun...@febo.com 
 [mailto:time-nuts-boun...@febo.com] Im Auftrag von Azelio Boriani
 Gesendet: Donnerstag, 23. Januar 2014 14:27
 An: Discussion of precise time and frequency measurement
 Betreff: Re: [time-nuts] Help for general GPIB problem
 
 
 Try to stop the HPIB driver... maybe the driver is reporting 
 as available even if no hardware is actually connected.
 
 On Thu, Jan 23, 2014 at 12:22 PM, Ulrich Bangert 
 df...@ulrich-bangert.de wrote:
  Gentlemen,
 
  I am just going to improve my EZGPIB utility so that it can 
 make use 
  of more than one GPIB-interface (supported by GPIB32.Dll, not 
  Prologix). I have been trying to enumerate all detected 
 interfaces by 
  using
 
  ibdev(bi,0,0,T300ms,0,1)
 
  in a loop where bi starts with 0 and is incremented by 
 1 until the 
  result of the call gets negative. Much to my surprise this loop 
  detects 4
  (!) interfaces GPIB0 to GPIB3 even if absolutely NO 
 interface is connected
  to the pc.
 
  What am I doing wrong. Is 4 the maximum number of interfaces that 
  may be handled by GPIB32.Dll 
 
  What do I need to do to find the real number of detected interfaces 
  ?
 
  Best regards and TIA for your answers
 
  Ulrich Bangert
  www.ulrich-bangert.de
  Ortholzer Weg 1
  27243 Gross Ippener
 
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Re: [time-nuts] Help for general GPIB problem

[Azelio Boriani]

OK, understood. So it seems that the next step is to try to connect
with those reported devices and see if an error is returned,
identifying the really connected ones from the placeholders...

On Thu, Jan 23, 2014 at 5:00 PM, Ulrich Bangert df...@ulrich-bangert.de wrote:
 Azelio,

 Try to stop the HPIB driver...

 I do not have any HPIB (=HP specific) driver in my system. Instead I use the
 GPIB32.DLL that comes together with every National Instruments GPIB
 interface adapter. The DLL is basically thought as the National Instruments
 support for C-Programmers but I wrote a wrapper unit to be able to use the
 DLL from my Delphi programming environment.

 The DLL is the BASIC translation between software and hardware and can
 hardly been left away. It is responsible for the fact that you can use the
 same DLL function calls regardless of what physical interface is used, i.e.
 it works with a PCI plugin card as well as with USB to GPIB adapters as well
 as with network based GPIB adapters (as long as the all come from NI). That
 is one of the really NEAT things with NI stuff.

 Best regards
 Ulrich



 -Ursprungliche Nachricht-
 Von: time-nuts-boun...@febo.com
 [mailto:time-nuts-boun...@febo.com] Im Auftrag von Azelio Boriani
 Gesendet: Donnerstag, 23. Januar 2014 14:27
 An: Discussion of precise time and frequency measurement
 Betreff: Re: [time-nuts] Help for general GPIB problem


 Try to stop the HPIB driver... maybe the driver is reporting
 as available even if no hardware is actually connected.

 On Thu, Jan 23, 2014 at 12:22 PM, Ulrich Bangert
 df...@ulrich-bangert.de wrote:
  Gentlemen,
 
  I am just going to improve my EZGPIB utility so that it can
 make use
  of more than one GPIB-interface (supported by GPIB32.Dll, not
  Prologix). I have been trying to enumerate all detected
 interfaces by
  using
 
  ibdev(bi,0,0,T300ms,0,1)
 
  in a loop where bi starts with 0 and is incremented by
 1 until the
  result of the call gets negative. Much to my surprise this loop
  detects 4
  (!) interfaces GPIB0 to GPIB3 even if absolutely NO
 interface is connected
  to the pc.
 
  What am I doing wrong. Is 4 the maximum number of interfaces that
  may be handled by GPIB32.Dll 
 
  What do I need to do to find the real number of detected interfaces
  ?
 
  Best regards and TIA for your answers
 
  Ulrich Bangert
  www.ulrich-bangert.de
  Ortholzer Weg 1
  27243 Gross Ippener
 
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Re: [time-nuts] Help for general GPIB problem

[John Miles]

You probably want ibfind() rather than ibdev().  Take a look at gpibport.cpp
in the TimeLab source (drivers/shared/gpibport.cpp under the installation
folder), in the enumerate_ports() function.  

-- john, KE5FX
Miles Design LLC

 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-
 boun...@febo.com] On Behalf Of Ulrich Bangert
 Sent: Thursday, January 23, 2014 3:23 AM
 To: Time nuts
 Subject: [time-nuts] Help for general GPIB problem
 
 Gentlemen,
 
 I am just going to improve my EZGPIB utility so that it can make use of
more
 than one GPIB-interface (supported by GPIB32.Dll, not Prologix). I have
 been
 trying to enumerate all detected interfaces by using
 
 ibdev(bi,0,0,T300ms,0,1)
 
 in a loop where bi starts with 0 and is incremented by 1 until the
 result of the call gets negative. Much to my surprise this loop detects 4
 (!) interfaces GPIB0 to GPIB3 even if absolutely NO interface is connected
 to the pc.
 
 What am I doing wrong. Is 4 the maximum number of interfaces that may
 be
 handled by GPIB32.Dll 
 
 What do I need to do to find the real number of detected interfaces ?
 
 Best regards and TIA for your answers
 
 Ulrich Bangert
 www.ulrich-bangert.de
 Ortholzer Weg 1
 27243 Gross Ippener
 
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[time-nuts] Help in Locking a Windows Computer to GPS Time

[Rex Moncur]

I am trying to lock a Windows XP computer to GPS time taking advantage of
both the NEMA sentence and the 1PPS with the hope of getting to within a few
ms.

I am using a Garmin GPS 18PC and the NMEATime program.  When I tick the box
to implement the 1PPS feature on NMEATime the program locks up each time it
attempts to correct the PC time.  Perhaps there is something I need to do to
configure the GPS 18PC to fix this.

I would be grateful for advice as to whether and how one can use NMEATime
for this purpose with a Garmin GPS 18 PC or advice on other programs to
achieve accurate locking of the PC.

Rex VK7MO

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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[David J Taylor]

I am trying to lock a Windows XP computer to GPS time taking advantage of
both the NEMA sentence and the 1PPS with the hope of getting to within a few
ms.

I am using a Garmin GPS 18PC and the NMEATime program.  When I tick the box
to implement the 1PPS feature on NMEATime the program locks up each time it
attempts to correct the PC time.  Perhaps there is something I need to do to
configure the GPS 18PC to fix this.

I would be grateful for advice as to whether and how one can use NMEATime
for this purpose with a Garmin GPS 18 PC or advice on other programs to
achieve accurate locking of the PC.

Rex VK7MO
==

Rex,

Does the GPS 18PC even have a PPS output?  A module which does is this one:

 http://www.adafruit.com/products/746

and there are lots of others.

With Windows-8 and a bit of luck, you don't even need the PPS to get within 
a millisecond - see:


 http://www.satsignal.eu/mrtg/bergen_ntp_2.html

and that's over a Wi-Fi connection!  More typically, though, using PPS will 
get you within a millisecond = how much depends on the version of Windows 
you are using:


 http://www.satsignal.eu/mrtg/performance_ntp.php#windows-stratum-1

(PC Feenix is currently playing up, hence the glitches)  PC Alta is 
Windows-7, and PC Stamsund Windows-8.  I also have an XP PC whose graphs are 
not so regularly updated:


 http://www.satsignal.eu/mrtg/Old-Feenix/feenix_ntp_2.html

using a ublox NEO 6M module from China.

Rather than NMEATime, which uses just a small subset of the capabilities on 
NTP, use the standard NTP software from Meinberg, installed as per my 
instructions here:


 http://www.satsignal.eu/ntp/setup.html

Once that is done, and you have the serial GPS recognised (its performance 
won't be that good), add the PPS support with the special driver, as 
documented here:


 http://www.satsignal.eu/ntp/NTP-on-Windows-Vista.html

Performance of a Windows-7 system using that kernel-mode driver is here:

 http://www.satsignal.eu/mrtg/alta_ntp_2.html

Averaged jitter of under 35 microseconds.  The Windows-8 system (where the 
more precise timestamp instructions are available in the OS) has jitter 
under 20 microseconds.


73,
David GM8ARV
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk 


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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[Chris Albertson]

It's simple, just install and run NTP
http://www.ntp.org/downloads.html


On Wed, Aug 21, 2013 at 9:02 PM, Rex Moncur rmon...@bigpond.net.au wrote:

 I am trying to lock a Windows XP computer to GPS time taking advantage of
 both the NEMA sentence and the 1PPS with the hope of getting to within a
 few
 ms.

 I am using a Garmin GPS 18PC and the NMEATime program.  When I tick the box
 to implement the 1PPS feature on NMEATime the program locks up each time it
 attempts to correct the PC time.  Perhaps there is something I need to do
 to
 configure the GPS 18PC to fix this.

 I would be grateful for advice as to whether and how one can use NMEATime
 for this purpose with a Garmin GPS 18 PC or advice on other programs to
 achieve accurate locking of the PC.

 Rex VK7MO

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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[Dimitry Borzenko]

 

 Hello. 

You can try  

  

Regards. 

 On 21/08/13 23:48 , Chris Albertson albertson.ch...@gmail.com sent:
  It's simple, just install and run NTP

 On Wed, Aug 21, 2013 at 9:02 PM, Rex Moncur  wrote:

  I am trying to lock a Windows XP computer to GPS time taking advantage
of
  both the NEMA sentence and the 1PPS with the hope of getting to within
a
  few
  ms.
 
  I am using a Garmin GPS 18PC and the NMEATime program. When I tick the
box
  to implement the 1PPS feature on NMEATime the program locks up each
time it
  attempts to correct the PC time. Perhaps there is something I need to
do
  to
  configure the GPS 18PC to fix this.
 
  I would be grateful for advice as to whether and how one can use
NMEATime
  for this purpose with a Garmin GPS 18 PC or advice on other programs to
  achieve accurate locking of the PC.
 
  Rex VK7MO
 
  ___
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  and follow the instructions there.
 

 -- 

 Chris Albertson
 Redondo Beach, California
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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[Chris Albertson]

Hit send a bit to soon.

NTP will use the best reference clocks it finds.  If that is GPS it will
use that.  It can also use other NTP servers.   Typically people use those
rather then getting their own GPS receiver.  If the PC has a network
connection you can likely get time to within a few milliseconds using NTP
and a few of the pool time servers.

I would defiantly recommend getting NTP to work using the pool servers
first.  Then add GPS.

Be warned that the NMEA spec says that messages apply to the current
second.  This means the NMEA data from the serial port can be up to one
second off.  It is used only to tell you the number of the second, not
for accurate timing.For that NTP uses the PPS reference clock.  On some
GPS receivers (not your Garmin unit) the PPS is good for a few tens of
nanoseconds.

I looked up NMEATime.  It uses SNTP protocol.  It will never be very
accurate.  Think about a mechanical clock that you want to set.  First to
set it then you wait a day or so and see if it gains or looses time.  Then
you adust the rate, faster or slower.  Eventually the clock keeps good time
after a few more cycles of adjust and wait and check.   NTP works like
this.  SNTP simply sets the clock once then quits and never even looks at
the rate.

This is the place to get NTP
http://www.ntp.org
However many Windows users like to get third party versions of NTP.  These
are packages with installers and are good for people who can't build and
install the source distribution.  Google should find one.

About your Garmin GPS.   You can buy a real timing receiver for under $20
on eBay.  If you need nanoseconds that is the way to go.   A timing
reciever will have at least two features (1) position hold, where the
receiver is told it is NOT moving and (2) self survey, where the reciever
can take about 30 minutes or longer to deterim it's position to typically
less than a meter.  Position uncertainty creates time uncertainty (by the
speed of light) so not knowing you location by a meter means you don't know
the time within about 3 nanoseconds.






On Wed, Aug 21, 2013 at 11:48 PM, Chris Albertson albertson.ch...@gmail.com
 wrote:

 It's simple, just install and run NTP
 http://www.ntp.org/downloads.html


 On Wed, Aug 21, 2013 at 9:02 PM, Rex Moncur rmon...@bigpond.net.auwrote:

 I am trying to lock a Windows XP computer to GPS time taking advantage of
 both the NEMA sentence and the 1PPS with the hope of getting to within a
 few
 ms.

 I am using a Garmin GPS 18PC and the NMEATime program.  When I tick the
 box
 to implement the 1PPS feature on NMEATime the program locks up each time
 it
 attempts to correct the PC time.  Perhaps there is something I need to do
 to
 configure the GPS 18PC to fix this.

 I would be grateful for advice as to whether and how one can use NMEATime
 for this purpose with a Garmin GPS 18 PC or advice on other programs to
 achieve accurate locking of the PC.

 Rex VK7MO

 ___
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 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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 --

 Chris Albertson
 Redondo Beach, California




-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[Dimitry Borzenko]

 

 Hello 

You can try Nmeatime: www.visualgps.net/NMEATime/ 

 Regards

 On 21/08/13 23:48 , Chris Albertson albertson.ch...@gmail.com sent:
  It's simple, just install and run NTP

 On Wed, Aug 21, 2013 at 9:02 PM, Rex Moncur  wrote:

  I am trying to lock a Windows XP computer to GPS time taking advantage
of
  both the NEMA sentence and the 1PPS with the hope of getting to within
a
  few
  ms.
 
  I am using a Garmin GPS 18PC and the NMEATime program. When I tick the
box
  to implement the 1PPS feature on NMEATime the program locks up each
time it
  attempts to correct the PC time. Perhaps there is something I need to
do
  to
  configure the GPS 18PC to fix this.
 
  I would be grateful for advice as to whether and how one can use
NMEATime
  for this purpose with a Garmin GPS 18 PC or advice on other programs to
  achieve accurate locking of the PC.
 
  Rex VK7MO
 
  ___
  time-nuts mailing list -- 
  To unsubscribe, go to
  
  and follow the instructions there.
 

 -- 

 Chris Albertson
 Redondo Beach, California
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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[David J Taylor]

Hello

You can try Nmeatime: www.visualgps.net/NMEATime/

Regards
===

Some advantages of the standard NTP software over NMEATime are listed here:

 http://www.satsignal.eu/ntp/setup.html#why

The OP's main problem is that his GPS receiver does not include PPS, but a 
new, low-cost receiver easily solves that problem.


Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk 


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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[Hal Murray]

albertson.ch...@gmail.com said:
 NTP will use the best reference clocks it finds.  If that is GPS it will
 use that.  It can also use other NTP servers.   Typically people use those
 rather then getting their own GPS receiver.  If the PC has a network
 connection you can likely get time to within a few milliseconds using NTP
 and a few of the pool time servers. 

I think you are missing the big picture.

The OP wanted GPS time.

NTP isn't setup to work with GPS time rather than UTC.

None of the typical low cost GPS/NMEA receivers tell you GPS time rather than 
UTC.  Some of them tell you the offset.

If you really want GPS time, you have two choices.
  One is to get UTC via NTP and the offset via IERS, USNO, and NIST, and 
probably others.
  This has troubles when the leap-second offset changes.

  The other would be to listen to various GPS devices and see if you can get 
GPS time rather than UTC.  It might work to hack various refclock drivers 
distributed with the NTP reference package.





-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[David J Taylor]

From: Hal Murray

I think you are missing the big picture.

The OP wanted GPS time.

NTP isn't setup to work with GPS time rather than UTC.
[]
=

I think the OP wants UTC time from a GPS rather than GPS time.  But even 
if it /was/ GPS time, couldn't a set of simple fudge statements in the NTP 
configuration provide that?  OK, you would need to change the fudge lines 
when the GPS to UTC offset changed...


Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk 


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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[Hal Murray]

 I think the OP wants UTC time from a GPS rather than GPS time.

In case, it should be simple.


 But even  if it /was/ GPS time, couldn't a set of simple fudge statements
 in the NTP  configuration provide that?  OK, you would need to change the
 fudge lines  when the GPS to UTC offset changed...

I think that would work.

Another complication is that there isn't any fudge offset for other servers 
(non refclocks) so you can't use normal servers running on UTC as a sanity 
check.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[Rex Moncur]

Hi David

Yes I did not make myself clear but I am looking for UTC time from a GPS.
Thanks for all your references which I will work through and see how I go.

Regards Rex VK7MO

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of David J Taylor
Sent: Thursday, 22 August 2013 6:24 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

From: Hal Murray

I think you are missing the big picture.

The OP wanted GPS time.

NTP isn't setup to work with GPS time rather than UTC.
[]
=

I think the OP wants UTC time from a GPS rather than GPS time.  But even
if it /was/ GPS time, couldn't a set of simple fudge statements in the NTP
configuration provide that?  OK, you would need to change the fudge lines
when the GPS to UTC offset changed...

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk 

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Re: [time-nuts] Help in Locking a Windows Computer to GPS Time

[David J Taylor]

From: Hal Murray


I think the OP wants UTC time from a GPS rather than GPS time.


In case, it should be simple.


But even  if it /was/ GPS time, couldn't a set of simple fudge 
statements

in the NTP  configuration provide that?  OK, you would need to change the
fudge lines  when the GPS to UTC offset changed...


I think that would work.

Another complication is that there isn't any fudge offset for other servers
(non refclocks) so you can't use normal servers running on UTC as a sanity
check.
===

Oh, if you can't use a fudge on other servers, that's a pity, and I wouldn't 
then trust such a fiddled clock.  Mind you, I can quite understand why it's 
not allowed!


Thanks, Hal.

David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk 


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[time-nuts] Help support the microwave addiction.

[Lizeth Norman]

Hi all!

Having finally moved and having been able to sort the stuff, there's
some goodies for sale:
Do have a few more items that would be of interest to the time and
frequency folks, but here's the first two.

I have two Shera based gpsdo kits available. One board is built,
tested and working.  The other is a complete kit of all parts and the
A+A engineering pc board.

Included in each kit:
1 HP 10811a-60111
1 sma unknown 5v active patch gps L1 antenna
1 HP 58535a gps active splitter
1 Motorola M12+T gps receiver

The built kit gets an HP rack mount enclosure with a LCD display of
the efc voltage. Feel free to use the boards inside, but as you will
see, it was my first attempt at a partial kit where YOU the builder
must buy to spec and then integrate according to a plan. Looks like
hell. Works ok, though..

Would like to trade for equipment. Particularly microwave attenuators,
mixers, preamps. Will trade + cash for a signal generator good to 18
GHz.

Kit one (built board with enclosure and power supply. Ask for photos.)
$250
Kit two
$210

All reasonable offers considered.

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Re: [time-nuts] Help support the microwave addiction.

[Edgardo Molina]

Hi,

May I see pictures of both kits off list please?  xe1xus at amsat dot org 
Thanks.

Regards,



Edgardo Molina
Dirección IPTEL

www.iptel.net.mx

T : 55 55 55202444
M : 04455 10045822

Piensa en Bits SA de CV



Información anexa:




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On Dec 8, 2012, at 6:59 PM, Lizeth Norman normanliz...@gmail.com wrote:

 Hi all!
 
 Having finally moved and having been able to sort the stuff, there's
 some goodies for sale:
 Do have a few more items that would be of interest to the time and
 frequency folks, but here's the first two.
 
 I have two Shera based gpsdo kits available. One board is built,
 tested and working.  The other is a complete kit of all parts and the
 A+A engineering pc board.
 
 Included in each kit:
 1 HP 10811a-60111
 1 sma unknown 5v active patch gps L1 antenna
 1 HP 58535a gps active splitter
 1 Motorola M12+T gps receiver
 
 The built kit gets an HP rack mount enclosure with a LCD display of
 the efc voltage. Feel free to use the boards inside, but as you will
 see, it was my first attempt at a partial kit where YOU the builder
 must buy to spec and then integrate according to a plan. Looks like
 hell. Works ok, though..
 
 Would like to trade for equipment. Particularly microwave attenuators,
 mixers, preamps. Will trade + cash for a signal generator good to 18
 GHz.
 
 Kit one (built board with enclosure and power supply. Ask for photos.)
 $250
 Kit two
 $210
 
 All reasonable offers considered.
 
 ___
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Re: [time-nuts] Help support the microwave addiction.

[Lizeth Norman]

Pictures at:
http://www.flickr.com/photos/n3ykf/

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[time-nuts] Help on processing some data

[Javier Herrero]

Hello,

I've several data sets of frequency measurements taken at 500us 
intervals, and would like to extract phase noise data from them. In 
order to do a consistency check with my processing, could I request some 
help from any of you that have available Stable32 or other similar tool 
to process one file?


Best regards,

Javier, EA1CRB


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Re: [time-nuts] Help with HAMEG HM8123

[K. Szeker]

Hi all,

Hello Dani, sorry, but you cannot find some documentations, with
schematics, over more newer Hameg equipments, in all cases not from Hameg!
:-(  Its practically a illusion  a real problem...
K.

2011/12/8 Daniel Mendes dmend...@gmail.com

 Maybe i´m blind but at the Hameg site I can only find one PDF with the
 manual in 4 different languages together (english, spanish, german and
 french) but no schematics...

 Daniel


 Date: Wed, 7 Dec 2011 19:52:58 -
 From: Alan Meliaalan.melia@btinternet.**com alan.me...@btinternet.com
 
 To: Discussion of precise time and frequency measurement
time-nuts@febo.com
 Subject: Re: [time-nuts] Help with HAMEG HM8123
 Message-ID:002301ccb519$**dc57c050$4001a8c0@lark
 Content-Type: text/plain;   charset=iso-8859-1


 Get a manual from the Hameg site
 http://www.hameg.com/manuals.**0.html?no_cache=1L=1%3Ehttp://www.hameg.com/manuals.0.html?no_cache=1L=1%3E
 You may find that the English versions do no always contain the circuit
 diagrams .in this case download the German language version which will
 have the circuits at the back

 Alan G3NYK

 - Original Message -
 From: Daniel Mendesdmend...@gmail.com
 To:time-nuts@febo.com
 Sent: Wednesday, December 07, 2011 6:43 PM
 Subject: [time-nuts] Help with HAMEG HM8123


 Hi, i?ve got a hameg HM8123 that came without any front panel button

 working. Opening it i found that both flat cables from the panel to the
 mainboard got loose. I figured where to plug the fist one (because it
 could only plug in one connector...  it was a tight fit) but the other
 can be plugged in 2 different receptacles at the mainboard. Does someone
 have a repair manual or internal photos of one of these?


 __**_
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/**
 mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.

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Re: [time-nuts] Help with HAMEG HM8123

[Daniel Mendes]

Maybe i´m blind but at the Hameg site I can only find one PDF with the manual 
in 4 different languages together (english, spanish, german and french) but no 
schematics...

Daniel


Date: Wed, 7 Dec 2011 19:52:58 -
From: Alan Meliaalan.me...@btinternet.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Help with HAMEG HM8123
Message-ID:002301ccb519$dc57c050$4001a8c0@lark
Content-Type: text/plain;   charset=iso-8859-1

Get a manual from the Hameg site
http://www.hameg.com/manuals.0.html?no_cache=1L=1%3E
You may find that the English versions do no always contain the circuit
diagrams .in this case download the German language version which will
have the circuits at the back

Alan G3NYK

- Original Message -
From: Daniel Mendesdmend...@gmail.com
To:time-nuts@febo.com
Sent: Wednesday, December 07, 2011 6:43 PM
Subject: [time-nuts] Help with HAMEG HM8123


Hi, i?ve got a hameg HM8123 that came without any front panel button
working. Opening it i found that both flat cables from the panel to the
mainboard got loose. I figured where to plug the fist one (because it
could only plug in one connector...  it was a tight fit) but the other
can be plugged in 2 different receptacles at the mainboard. Does someone
have a repair manual or internal photos of one of these?


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and follow the instructions there.

Re: [time-nuts] Help with HAMEG HM8123

[Alan Melia]

Hi Danial I admit I have only downloaded scope manuals but for many of those
the schematics are only at the end of the German language version. They are
usually quite helpful so it might be worth contacting them.

Alan
G3NYK

- Original Message - 
From: Daniel Mendes dmend...@gmail.com
To: time-nuts@febo.com
Sent: Thursday, December 08, 2011 11:15 AM
Subject: Re: [time-nuts] Help with HAMEG HM8123


Maybe i´m blind but at the Hameg site I can only find one PDF with the
manual in 4 different languages together (english, spanish, german and
french) but no schematics...

Daniel


Date: Wed, 7 Dec 2011 19:52:58 -
From: Alan Meliaalan.me...@btinternet.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Help with HAMEG HM8123
Message-ID:002301ccb519$dc57c050$4001a8c0@lark
Content-Type: text/plain; charset=iso-8859-1

Get a manual from the Hameg site
http://www.hameg.com/manuals.0.html?no_cache=1L=1%3E
You may find that the English versions do no always contain the circuit
diagrams .in this case download the German language version which will
have the circuits at the back

Alan G3NYK

- Original Message -
From: Daniel Mendesdmend...@gmail.com
To:time-nuts@febo.com
Sent: Wednesday, December 07, 2011 6:43 PM
Subject: [time-nuts] Help with HAMEG HM8123


Hi, i?ve got a hameg HM8123 that came without any front panel button
working. Opening it i found that both flat cables from the panel to the
mainboard got loose. I figured where to plug the fist one (because it
could only plug in one connector...  it was a tight fit) but the other
can be plugged in 2 different receptacles at the mainboard. Does someone
have a repair manual or internal photos of one of these?


___
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To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


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Re: [time-nuts] Help with TCXO

[Azelio Boriani]

Yes, I remember that thread.
Anyway, Hal, are you suggesting to use the 3.2GHz clock to crank up the
counting speed? OK, strange, but can be a way...

On Wed, Dec 7, 2011 at 1:23 AM, Bob Camp li...@rtty.us wrote:

 Hi

 There was a point in time where a general purpose board could have been
 done on a group basis. The discussion of that offended some on the list.
 That prevented it from being done in a timely manner. The funds that would
 have gone to the project went to a closed design that is not available.

 Sorry about that.

 Bob



 On Dec 6, 2011, at 5:11 PM, Attila Kinali att...@kinali.ch wrote:

  On Tue, 6 Dec 2011 17:06:43 -0500
  Bob Camp li...@rtty.us wrote:
 
  It's the wave union one that the Fermi labs papers talk about. We
 started
  talking about a group design on one a while back. Ultimately it got
 taken
  off list 
 
  What is the status of that?
  I would try to help if i didnt know that i have way too
  little time currently :-(
 
 Attila Kinali
  --
  Why does it take years to find the answers to
  the questions one should have asked long ago?
 
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[time-nuts] Help with HAMEG HM8123

[Daniel Mendes]

Hi, i´ve got a hameg HM8123 that came without any front panel button 
working. Opening it i found that both flat cables from the panel to the 
mainboard got loose. I figured where to plug the fist one (because it 
could only plug in one connector...  it was a tight fit) but the other 
can be plugged in 2 different receptacles at the mainboard. Does someone 
have a repair manual or internal photos of one of these?


Thank you.

An aspiring time nut,

Daniel

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and follow the instructions there.

Re: [time-nuts] Help with HAMEG HM8123

[Alan Melia]

Get a manual from the Hameg site
http://www.hameg.com/manuals.0.html?no_cache=1L=1%3E
You may find that the English versions do no always contain the circuit
diagrams .in this case download the German language version which will
have the circuits at the back

Alan G3NYK

- Original Message - 
From: Daniel Mendes dmend...@gmail.com
To: time-nuts@febo.com
Sent: Wednesday, December 07, 2011 6:43 PM
Subject: [time-nuts] Help with HAMEG HM8123


Hi, i´ve got a hameg HM8123 that came without any front panel button
working. Opening it i found that both flat cables from the panel to the
mainboard got loose. I figured where to plug the fist one (because it
could only plug in one connector...  it was a tight fit) but the other
can be plugged in 2 different receptacles at the mainboard. Does someone
have a repair manual or internal photos of one of these?

Thank you.

An aspiring time nut,

Daniel

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To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


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Re: [time-nuts] Help with TCXO

[Attila Kinali]

On Tue, 29 Nov 2011 16:09:34 +0100
Azelio Boriani azelio.bori...@screen.it wrote:

 FPGA time interval counter? With an analog interpolator? No? Then, at most,
 you will get a nS resolution. I have a 2.5nS resolution TIC with 100MHz
 clock using four phases from the Xilinx DCM in a Spartan3.

I'm quite sure you can do better than ns resolution with an analog
interpolator. Heck, even the PICTIC does something arount 200ps 
if i'm not mistaken. And the PICTIC has a quite simple design too.

Attila Kinali
-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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Re: [time-nuts] Help with TCXO

[Attila Kinali]

On Tue, 29 Nov 2011 11:23:26 +1100
Michael Malloy mech...@gmail.com wrote:

 let me know if you want schematics for my other designs

I'm always interested in learning from others.
So, if it would be not too much a hassle, i'd greatly
appreciate if you could publish yous schematics/designs.
Especially, if you can write a few words on what your
design decisions were.

Attila Kinali
-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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Re: [time-nuts] Help with TCXO

[Azelio Boriani]

Yes, with an analog interpolator you can. Without an analog interpolator
and without using the vernier delay line (and other tricks like that), the
FPGA can only get to nS resolution so far (for example, in a Spartan3 or
equivalent). To implement a vernier delay line you need also to control the
logic translator and the technology fitter and know by heart your logic
chip. Maybe one day they pop up with a time-nut FPGA compiler that is aware
of intentionally-placed delay lines and stuff like this.

On Tue, Dec 6, 2011 at 3:43 PM, Attila Kinali att...@kinali.ch wrote:

 On Tue, 29 Nov 2011 11:23:26 +1100
 Michael Malloy mech...@gmail.com wrote:

  let me know if you want schematics for my other designs

 I'm always interested in learning from others.
 So, if it would be not too much a hassle, i'd greatly
 appreciate if you could publish yous schematics/designs.
 Especially, if you can write a few words on what your
 design decisions were.

Attila Kinali
 --
 The trouble with you, Shev, is you don't say anything until you've saved
 up a whole truckload of damned heavy brick arguments and then you dump
 them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [time-nuts] Help with TCXO

[Bob Camp]

Hi

Actually you can get to sub ns resolution with a delay line in a modern
cheap FPGA. Weather you can get to sub 50 ps across the full window is open
to a bit of debate. 

The amount of hassle goes up as your resolution gets better. Without heroic
efforts, sub 200 ps is quite possible. 

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Azelio Boriani
Sent: Tuesday, December 06, 2011 10:25 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Help with TCXO

Yes, with an analog interpolator you can. Without an analog interpolator
and without using the vernier delay line (and other tricks like that), the
FPGA can only get to nS resolution so far (for example, in a Spartan3 or
equivalent). To implement a vernier delay line you need also to control the
logic translator and the technology fitter and know by heart your logic
chip. Maybe one day they pop up with a time-nut FPGA compiler that is aware
of intentionally-placed delay lines and stuff like this.

On Tue, Dec 6, 2011 at 3:43 PM, Attila Kinali att...@kinali.ch wrote:

 On Tue, 29 Nov 2011 11:23:26 +1100
 Michael Malloy mech...@gmail.com wrote:

  let me know if you want schematics for my other designs

 I'm always interested in learning from others.
 So, if it would be not too much a hassle, i'd greatly
 appreciate if you could publish yous schematics/designs.
 Especially, if you can write a few words on what your
 design decisions were.

Attila Kinali
 --
 The trouble with you, Shev, is you don't say anything until you've saved
 up a whole truckload of damned heavy brick arguments and then you dump
 them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.

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Re: [time-nuts] Help with TCXO

[Azelio Boriani]

I have read about the two main delay line techniques: the vernier delay
line and the tapped delay line. These require a sort of on-the-fly
calibration virtually for every sample you get because of the temperature
and power supply dependency of the delay itself. Presently my
time-to-digital converter has a 2.5nS resolution made only by counters,
based on a 100MHz clock and on the capabilities of the Digital Clock
Manager in the Spartan3 XC3S50 FPGA. In your opinion what resolution can I
get from a Spartan3 (without any calibration) using delay lines? I have to
learn how to manage delay lines and how to direct their placement for
time-nut purposes.

On Tue, Dec 6, 2011 at 6:11 PM, Bob Camp li...@rtty.us wrote:

 Hi

 Actually you can get to sub ns resolution with a delay line in a modern
 cheap FPGA. Weather you can get to sub 50 ps across the full window is open
 to a bit of debate.

 The amount of hassle goes up as your resolution gets better. Without heroic
 efforts, sub 200 ps is quite possible.

 Bob

 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of Azelio Boriani
 Sent: Tuesday, December 06, 2011 10:25 AM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Help with TCXO

 Yes, with an analog interpolator you can. Without an analog interpolator
 and without using the vernier delay line (and other tricks like that), the
 FPGA can only get to nS resolution so far (for example, in a Spartan3 or
 equivalent). To implement a vernier delay line you need also to control the
 logic translator and the technology fitter and know by heart your logic
 chip. Maybe one day they pop up with a time-nut FPGA compiler that is aware
 of intentionally-placed delay lines and stuff like this.

 On Tue, Dec 6, 2011 at 3:43 PM, Attila Kinali att...@kinali.ch wrote:

  On Tue, 29 Nov 2011 11:23:26 +1100
  Michael Malloy mech...@gmail.com wrote:
 
   let me know if you want schematics for my other designs
 
  I'm always interested in learning from others.
  So, if it would be not too much a hassle, i'd greatly
  appreciate if you could publish yous schematics/designs.
  Especially, if you can write a few words on what your
  design decisions were.
 
 Attila Kinali
  --
  The trouble with you, Shev, is you don't say anything until you've saved
  up a whole truckload of damned heavy brick arguments and then you dump
  them all out and never look at the bleeding body mangled beneath the heap
 -- Tirin, The Dispossessed, U. Le Guin
 
  ___
  time-nuts mailing list -- time-nuts@febo.com
  To unsubscribe, go to
  https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
  and follow the instructions there.
 
 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.


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Re: [time-nuts] Help with TCXO

[Bob Camp]

Hi

With reasonable calibration, it looks like you can get below 200 ps. You
will need to boost the clock up to ~ 400 MHz with one of the internal PLL's
to get it to fit in a reasonable sized device.

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Azelio Boriani
Sent: Tuesday, December 06, 2011 3:47 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Help with TCXO

I have read about the two main delay line techniques: the vernier delay
line and the tapped delay line. These require a sort of on-the-fly
calibration virtually for every sample you get because of the temperature
and power supply dependency of the delay itself. Presently my
time-to-digital converter has a 2.5nS resolution made only by counters,
based on a 100MHz clock and on the capabilities of the Digital Clock
Manager in the Spartan3 XC3S50 FPGA. In your opinion what resolution can I
get from a Spartan3 (without any calibration) using delay lines? I have to
learn how to manage delay lines and how to direct their placement for
time-nut purposes.

On Tue, Dec 6, 2011 at 6:11 PM, Bob Camp li...@rtty.us wrote:

 Hi

 Actually you can get to sub ns resolution with a delay line in a modern
 cheap FPGA. Weather you can get to sub 50 ps across the full window is
open
 to a bit of debate.

 The amount of hassle goes up as your resolution gets better. Without
heroic
 efforts, sub 200 ps is quite possible.

 Bob

 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of Azelio Boriani
 Sent: Tuesday, December 06, 2011 10:25 AM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Help with TCXO

 Yes, with an analog interpolator you can. Without an analog interpolator
 and without using the vernier delay line (and other tricks like that), the
 FPGA can only get to nS resolution so far (for example, in a Spartan3 or
 equivalent). To implement a vernier delay line you need also to control
the
 logic translator and the technology fitter and know by heart your logic
 chip. Maybe one day they pop up with a time-nut FPGA compiler that is
aware
 of intentionally-placed delay lines and stuff like this.

 On Tue, Dec 6, 2011 at 3:43 PM, Attila Kinali att...@kinali.ch wrote:

  On Tue, 29 Nov 2011 11:23:26 +1100
  Michael Malloy mech...@gmail.com wrote:
 
   let me know if you want schematics for my other designs
 
  I'm always interested in learning from others.
  So, if it would be not too much a hassle, i'd greatly
  appreciate if you could publish yous schematics/designs.
  Especially, if you can write a few words on what your
  design decisions were.
 
 Attila Kinali
  --
  The trouble with you, Shev, is you don't say anything until you've saved
  up a whole truckload of damned heavy brick arguments and then you dump
  them all out and never look at the bleeding body mangled beneath the
heap
 -- Tirin, The Dispossessed, U. Le Guin
 
  ___
  time-nuts mailing list -- time-nuts@febo.com
  To unsubscribe, go to
  https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
  and follow the instructions there.
 
 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
 https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.


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 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
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Re: [time-nuts] Help with TCXO

[Attila Kinali]

On Tue, 6 Dec 2011 16:43:37 -0500
Bob Camp li...@rtty.us wrote:

 With reasonable calibration, it looks like you can get below 200 ps. You
 will need to boost the clock up to ~ 400 MHz with one of the internal PLL's
 to get it to fit in a reasonable sized device.

With which design would that be?

Attila Kinali
-- 
Why does it take years to find the answers to
the questions one should have asked long ago?

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