[time-nuts] Trimble/Symmetricom Reverse Engineering

[Bryan _]

Hello:
For those who have or interested in the Trimble/Symmetricom units found on flea 
bay, here is a link to a user who posted some information on the 50 pin header 
pin.
http://tipok.org.ua/node/53
-=Bryan=-
  
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Re: [time-nuts] Tbolt issues

[Bob kb8tq]

Hi

The problem is that ADEV is not really the best tool for measuring / modeling 
narrow band noise. There are other measures that are better. None of them 
really give you a direct connection to a band limited noise process. Without a 
model for the process, coming up with a max limit is just speculation. It is 
frighteningly easy to come up with nasty processes that look fine when viewed 
with this or that measure. The repeated requests on list for raw data are a 
direct result of people having seen this.

Bob

> On Sep 2, 2016, at 5:06 PM, Lars Walenius  wrote:
> 
> You are absolute right in that it is a that depends sort of things. 
> 
> Fast temperature changes might really be something that upsets a GPSDO 
> especially if the time constant is long. 
> 
> By taking temperature data and multiply with your oscillators temperature 
> coefficient you can do ADEV for the temperature dependence. Quite interesting 
> especially with an HVAC or the sun shining on the GPSDO! Or you can simply 
> take the maximum temperature shift x temperature coefficient for the same 
> time as your GPSDO  time constant to estimate the frequency error you can 
> have depending on the temperature. Of course that is also a that depend sort 
> of thing but at least gives an indication. Say that you have for example a 
> time constant of 1000secs and a temperature change of 2°C during 1000secs and 
> a temperature coefficient of 5E-11/°C that will give you a change of 1E-10 
> and the loop will not manage to compensate for it in time.
> 
> Lars
> 
>> From: Bob
>> Skickat: den 2 september 2016 22:00
> 
>> Since the measurement in the frequency domain is a "peak" measure, you need 
>> to convert both to frequency error and to an absolute max. If you *do* care 
>> about the one second per day (or 10 days) as some do, that is a different 
>> factor than one second out of two minutes. Since the noise is likely not to 
>> be white noise, the factor is one of those "that depends" sort of things. It 
>> includes messy stuff like the room temperature changes and the control 
>> loop's response to them. In some designs the response may be multi level. 
>> The temp transient hits the voltage reference, DAC, and crystal in the OCXO 
>> at different times...
> 
>> Bob
> 
>>> On Sep 2, 2016, at 3:08 PM, Lars Walenius  wrote:
>> 
>> I might be completely wrong with my ”quick rule of thumb” (frequency 
>> accuracy: 10x the worst ADEV at all Taus longer than the gate time). but my 
>> assumptions are these:
>> 
>> 1. You have a GPSDO. (A free running oscillator as a rubidium or OCXO will 
>> not work if that is what you call a ”normal” frequency standard).
>> 2. The GPSDO design is such that the frequency error goes towards zero the 
>> longer time you measure the frequency. Otherwise you can say nothing from 
>> the ADEV to the absolute frequency error I think.
>> 3. ADEV can be seen as the standard deviation of all differences in 
>> frequency between two nearby frequency measurements (with no dead times) 
>> multiplied with a small factor (sqrt 0.5).
>> 4. Absolute frequency errors will at least be in the same range as the 
>> differences if the long-term error is near zero.
>> 5. It will always be larger frequency errors for shorter times. My 
>> assumption is for example that at 100 seconds you have 30ppt frequency error 
>> that is 3ns drift in 100seconds, If you plot that as straight line you will 
>> also have 30ppt at all shorter ”gate times”. If the line isn´t straight you 
>> will always find ”points” that has more than 30ppt frequency errors.
>> 6. At least around the Taus similar to the time constant of the GPSDO 
>> especially the GPS noise will give peak frequency errors compared to the 
>> average that are quite high. A factor of ten may be very conservative but as 
>> can be seen in the Tbolt measurements by TvB it is quite close. With OCXO 
>> and Rb GPSDO´s that I have tried to optimize I have seen about this factor 
>> or slightly less. With the DOT050 VCTCXO the ratio was even higher, up to 14 
>> (ADEV 7E-11 1-100secs and 1E-9 max freq errors at 1 second gate time).
>> 
>> Lars
>> 
>>> From: Bob
>>> Sent: den 2 september 2016 15:20
>> 
>>> The GPSDO might have an ADEV of 1 ppt at 1 sec and that rises to 30 ppt at 
>>> 100 sec. It also might not, but let's use those numbers.
>> 
>>> ADEV is a standard deviation. You can get an idea of the magnitude of the 
>>> change reading to reading from it. It does not give you a sign for that 
>>> change. In the case above, it is a good bet that you see strings of 1 sec 
>>> data with mostly the same sign.  They have to add up to the 30X larger 
>>> number when tau gets to 100 sec.
>> 
>>> That creates a major problem if you just look at the 1 sec data. A "normal" 
>>> frequency standard does not have a rise or bump like that in the ADEV plot. 
>>> Thus the quick rule of thumb stuff falls apart. The correct way to do it 
>>> will 

Re: [time-nuts] What's the best Windows 10 ntp client?

[Clay Autery]

PS

I am running BOTH the Meinberg ntpd AND the monitor...

My fault for allowing you to make me doubt myself  .

__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389

On 9/2/2016 8:09 AM, Martin Burnicki wrote:
> Clay Autery wrote:
>> NTP Time Server Monitor by Meinberg.
> Sorry, no.
>
> As the name suggests this is only a *monitor* program for NTP service
> (ntpd). You can use it to start/stop the NTP service, have a graphical
> presentation of the loopstats files optionally generated by ntpd, etc.
>
> So this is a nice optional addon for ntpd, but you need ntpd to actually
> synchronize the system time. The monitor program doesn't do that.
>
> Martin (working @meinberg)
>

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Re: [time-nuts] What's the best Windows 10 ntp client?

[Clay Autery]

Well then the ntpd program written into MY Windows CONTROLLED by the
program represented in the attached image

It says it is a Monitor, but it ALSO controls how NTP works on MY machine...

It keeps my computer as accurate as can be expected considering I'm
using remote server sources and wireless connection to the internet...

I'll worry about compiling my own ntpd, et al. once I decide to run my
own stratum 1 server...

I'm pretty consistently within +/- 4 milliseconds at any given time... 
usually < +/- 2 ms.

__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389

On 9/2/2016 8:09 AM, Martin Burnicki wrote:
> Clay Autery wrote:
>> NTP Time Server Monitor by Meinberg.
> Sorry, no.
>
> As the name suggests this is only a *monitor* program for NTP service
> (ntpd). You can use it to start/stop the NTP service, have a graphical
> presentation of the loopstats files optionally generated by ntpd, etc.
>
> So this is a nice optional addon for ntpd, but you need ntpd to actually
> synchronize the system time. The monitor program doesn't do that.
>
> Martin (working @meinberg)

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Re: [time-nuts] Tbolt issues

[Lars Walenius]

You are absolute right in that it is a that depends sort of things. 

Fast temperature changes might really be something that upsets a GPSDO 
especially if the time constant is long. 

By taking temperature data and multiply with your oscillators temperature 
coefficient you can do ADEV for the temperature dependence. Quite interesting 
especially with an HVAC or the sun shining on the GPSDO! Or you can simply take 
the maximum temperature shift x temperature coefficient for the same time as 
your GPSDO  time constant to estimate the frequency error you can have 
depending on the temperature. Of course that is also a that depend sort of 
thing but at least gives an indication. Say that you have for example a time 
constant of 1000secs and a temperature change of 2°C during 1000secs and a 
temperature coefficient of 5E-11/°C that will give you a change of 1E-10 and 
the loop will not manage to compensate for it in time.

Lars

>From: Bob
>Skickat: den 2 september 2016 22:00

>Since the measurement in the frequency domain is a "peak" measure, you need to 
>convert both to frequency error and to an absolute max. If you *do* care about 
>the one second per day (or 10 days) as some do, that is a different factor 
>than one second out of two minutes. Since the noise is likely not to be white 
>noise, the factor is one of those "that depends" sort of things. It includes 
>messy stuff like the room temperature changes and the control loop's response 
>to them. In some designs the response may be multi level. The temp transient 
>hits the voltage reference, DAC, and crystal in the OCXO at different times...

>Bob

>> On Sep 2, 2016, at 3:08 PM, Lars Walenius  wrote:
> 
> I might be completely wrong with my ”quick rule of thumb” (frequency 
> accuracy: 10x the worst ADEV at all Taus longer than the gate time). but my 
> assumptions are these:
> 
> 1. You have a GPSDO. (A free running oscillator as a rubidium or OCXO will 
> not work if that is what you call a ”normal” frequency standard).
> 2. The GPSDO design is such that the frequency error goes towards zero the 
> longer time you measure the frequency. Otherwise you can say nothing from the 
> ADEV to the absolute frequency error I think.
> 3. ADEV can be seen as the standard deviation of all differences in frequency 
> between two nearby frequency measurements (with no dead times) multiplied 
> with a small factor (sqrt 0.5).
> 4. Absolute frequency errors will at least be in the same range as the 
> differences if the long-term error is near zero.
> 5. It will always be larger frequency errors for shorter times. My assumption 
> is for example that at 100 seconds you have 30ppt frequency error that is 3ns 
> drift in 100seconds, If you plot that as straight line you will also have 
> 30ppt at all shorter ”gate times”. If the line isn´t straight you will always 
> find ”points” that has more than 30ppt frequency errors.
> 6. At least around the Taus similar to the time constant of the GPSDO 
> especially the GPS noise will give peak frequency errors compared to the 
> average that are quite high. A factor of ten may be very conservative but as 
> can be seen in the Tbolt measurements by TvB it is quite close. With OCXO and 
> Rb GPSDO´s that I have tried to optimize I have seen about this factor or 
> slightly less. With the DOT050 VCTCXO the ratio was even higher, up to 14 
> (ADEV 7E-11 1-100secs and 1E-9 max freq errors at 1 second gate time).
> 
> Lars
> 
>> From: Bob
>> Sent: den 2 september 2016 15:20
> 
>> The GPSDO might have an ADEV of 1 ppt at 1 sec and that rises to 30 ppt at 
>> 100 sec. It also might not, but let's use those numbers.
> 
>> ADEV is a standard deviation. You can get an idea of the magnitude of the 
>> change reading to reading from it. It does not give you a sign for that 
>> change. In the case above, it is a good bet that you see strings of 1 sec 
>> data with mostly the same sign.  They have to add up to the 30X larger 
>> number when tau gets to 100 sec.
> 
>> That creates a major problem if you just look at the 1 sec data. A "normal" 
>> frequency standard does not have a rise or bump like that in the ADEV plot. 
>> Thus the quick rule of thumb stuff falls apart. The correct way to do it 
>> will always be to work out what the noise process is and calculate based on 
>> it. That is not a popular thing to do 
> 
>> Bob
> 
>> On Sep 2, 2016, at 6:38 AM, Lars Walenius wrote:
>> 
>> Hello Bert,
>> 
>> For me your findings look very much the same as this:
>> http://www.leapsecond.com/pages/tbolt-8d/ 
>> At least for me I should say the (absolute) frequency accuracy for this 
>> Tbolt is not better than +-1E10 with 1 or 10 seconds gate times on a 
>> counter. Maybe I am totally wrong as both Tom and Charles says that your 
>> Tbolt is bad.
>> 
>> As Bob Camp said we need a confidence interval. For me in this case it is 
>> peak values if they occur more than a couple of times. Think of  voltmeters. 
>> 

Re: [time-nuts] Tbolt issues

[Bob kb8tq]

Hi

Since the measurement in the frequency domain is a "peak" measure, you need to 
convert both to frequency error and to an absolute max. If you *do* care about 
the one second per day (or 10 days) as some do, that is a different factor than 
one second out of two minutes. Since the noise is likely not to be white noise, 
the factor is one of those "that depends" sort of things. It includes messy 
stuff like the room temperature changes and the control loop's response to 
them. In some designs the response may be multi level. The temp transient hits 
the voltage reference, DAC, and crystal in the OCXO at different times...

Bob

> On Sep 2, 2016, at 3:08 PM, Lars Walenius  wrote:
> 
> I might be completely wrong with my ”quick rule of thumb” (frequency 
> accuracy: 10x the worst ADEV at all Taus longer than the gate time). but my 
> assumptions are these:
> 
> 1. You have a GPSDO. (A free running oscillator as a rubidium or OCXO will 
> not work if that is what you call a ”normal” frequency standard).
> 2. The GPSDO design is such that the frequency error goes towards zero the 
> longer time you measure the frequency. Otherwise you can say nothing from the 
> ADEV to the absolute frequency error I think.
> 3. ADEV can be seen as the standard deviation of all differences in frequency 
> between two nearby frequency measurements (with no dead times) multiplied 
> with a small factor (sqrt 0.5).
> 4. Absolute frequency errors will at least be in the same range as the 
> differences if the long-term error is near zero.
> 5. It will always be larger frequency errors for shorter times. My assumption 
> is for example that at 100 seconds you have 30ppt frequency error that is 3ns 
> drift in 100seconds, If you plot that as straight line you will also have 
> 30ppt at all shorter ”gate times”. If the line isn´t straight you will always 
> find ”points” that has more than 30ppt frequency errors.
> 6. At least around the Taus similar to the time constant of the GPSDO 
> especially the GPS noise will give peak frequency errors compared to the 
> average that are quite high. A factor of ten may be very conservative but as 
> can be seen in the Tbolt measurements by TvB it is quite close. With OCXO and 
> Rb GPSDO´s that I have tried to optimize I have seen about this factor or 
> slightly less. With the DOT050 VCTCXO the ratio was even higher, up to 14 
> (ADEV 7E-11 1-100secs and 1E-9 max freq errors at 1 second gate time).
> 
> Lars
> 
>> From: Bob
>> Sent: den 2 september 2016 15:20
> 
>> The GPSDO might have an ADEV of 1 ppt at 1 sec and that rises to 30 ppt at 
>> 100 sec. It also might not, but let's use those numbers.
> 
>> ADEV is a standard deviation. You can get an idea of the magnitude of the 
>> change reading to reading from it. It does not give you a sign for that 
>> change. In the case above, it is a good bet that you see strings of 1 sec 
>> data with mostly the same sign.  They have to add up to the 30X larger 
>> number when tau gets to 100 sec.
> 
>> That creates a major problem if you just look at the 1 sec data. A "normal" 
>> frequency standard does not have a rise or bump like that in the ADEV plot. 
>> Thus the quick rule of thumb stuff falls apart. The correct way to do it 
>> will always be to work out what the noise process is and calculate based on 
>> it. That is not a popular thing to do 
> 
>> Bob
> 
>> On Sep 2, 2016, at 6:38 AM, Lars Walenius wrote:
>> 
>> Hello Bert,
>> 
>> For me your findings look very much the same as this:
>> http://www.leapsecond.com/pages/tbolt-8d/ 
>> At least for me I should say the (absolute) frequency accuracy for this 
>> Tbolt is not better than +-1E10 with 1 or 10 seconds gate times on a 
>> counter. Maybe I am totally wrong as both Tom and Charles says that your 
>> Tbolt is bad.
>> 
>> As Bob Camp said we need a confidence interval. For me in this case it is 
>> peak values if they occur more than a couple of times. Think of  voltmeters. 
>> If it is out of spec say for only a couple of hours but it happens several 
>> times say during a month or year and the voltmeters is not considered bad I 
>> should say change the spec. If I were going to use the Tbolt as a reference 
>> in a production environment with a 1 or 10 sec gate time I probably would 
>> set the internal spec to 2E-10.
>> 
>> If I understand correct the Tracor 527E has a low pass filter with a time 
>> constant of 1second so the 1 second frequency average data should be 
>> relevant.
>> 
>> As I am also interested in frequency accuracy with GPSDO´s used with 
>> frequency counters, I have a maybe far to simplistic rule of accuracy: (10x 
>> the worst ADEV at all Taus longer than the gate time). So for the Tbolt with 
>> time constant of 100 seconds it is a hump of about 1E-11 at 100seconds so at 
>> gate times shorter than 100seconds I expect to see excursions up to 1E-10. 
>> If you set the time constant to 1000seconds and the OCXO in the Thunderbolt 

Re: [time-nuts] Tbolt issues

[Lars Walenius]

I might be completely wrong with my ”quick rule of thumb” (frequency accuracy: 
10x the worst ADEV at all Taus longer than the gate time). but my assumptions 
are these:

1. You have a GPSDO. (A free running oscillator as a rubidium or OCXO will not 
work if that is what you call a ”normal” frequency standard).
2. The GPSDO design is such that the frequency error goes towards zero the 
longer time you measure the frequency. Otherwise you can say nothing from the 
ADEV to the absolute frequency error I think.
3. ADEV can be seen as the standard deviation of all differences in frequency 
between two nearby frequency measurements (with no dead times) multiplied with 
a small factor (sqrt 0.5).
4. Absolute frequency errors will at least be in the same range as the 
differences if the long-term error is near zero.
5. It will always be larger frequency errors for shorter times. My assumption 
is for example that at 100 seconds you have 30ppt frequency error that is 3ns 
drift in 100seconds, If you plot that as straight line you will also have 30ppt 
at all shorter ”gate times”. If the line isn´t straight you will always find 
”points” that has more than 30ppt frequency errors.
6. At least around the Taus similar to the time constant of the GPSDO 
especially the GPS noise will give peak frequency errors compared to the 
average that are quite high. A factor of ten may be very conservative but as 
can be seen in the Tbolt measurements by TvB it is quite close. With OCXO and 
Rb GPSDO´s that I have tried to optimize I have seen about this factor or 
slightly less. With the DOT050 VCTCXO the ratio was even higher, up to 14 (ADEV 
7E-11 1-100secs and 1E-9 max freq errors at 1 second gate time).

Lars

>From: Bob
>Sent: den 2 september 2016 15:20

>The GPSDO might have an ADEV of 1 ppt at 1 sec and that rises to 30 ppt at 100 
>sec. It also might not, but let's use those numbers.

>ADEV is a standard deviation. You can get an idea of the magnitude of the 
>change reading to reading from it. It does not give you a sign for that 
>change. In the case above, it is a good bet that you see strings of 1 sec data 
>with mostly the same sign.  They have to add up to the 30X larger number when 
>tau gets to 100 sec.

>That creates a major problem if you just look at the 1 sec data. A "normal" 
>frequency standard does not have a rise or bump like that in the ADEV plot. 
>Thus the quick rule of thumb stuff falls apart. The correct way to do it will 
>always be to work out what the noise process is and calculate based on it. 
>That is not a popular thing to do 

>Bob

> On Sep 2, 2016, at 6:38 AM, Lars Walenius wrote:
> 
> Hello Bert,
> 
> For me your findings look very much the same as this:
> http://www.leapsecond.com/pages/tbolt-8d/ 
> At least for me I should say the (absolute) frequency accuracy for this Tbolt 
> is not better than +-1E10 with 1 or 10 seconds gate times on a counter. Maybe 
> I am totally wrong as both Tom and Charles says that your Tbolt is bad.
> 
> As Bob Camp said we need a confidence interval. For me in this case it is 
> peak values if they occur more than a couple of times. Think of  voltmeters. 
> If it is out of spec say for only a couple of hours but it happens several 
> times say during a month or year and the voltmeters is not considered bad I 
> should say change the spec. If I were going to use the Tbolt as a reference 
> in a production environment with a 1 or 10 sec gate time I probably would set 
> the internal spec to 2E-10.
> 
> If I understand correct the Tracor 527E has a low pass filter with a time 
> constant of 1second so the 1 second frequency average data should be relevant.
> 
> As I am also interested in frequency accuracy with GPSDO´s used with 
> frequency counters, I have a maybe far to simplistic rule of accuracy: (10x 
> the worst ADEV at all Taus longer than the gate time). So for the Tbolt with 
> time constant of 100 seconds it is a hump of about 1E-11 at 100seconds so at 
> gate times shorter than 100seconds I expect to see excursions up to 1E-10. If 
> you set the time constant to 1000seconds and the OCXO in the Thunderbolt is 
> good to 2 to 3E-12 all the way 1-1000 seconds you probably don´t have 
> excursions higher than 2 to 3E-11 at 1-100 seconds gate times.
> 
> Lars
> 
> 
> Från: Bert Kehren via time-nuts
> Skickat: den 1 september 2016 19:09
> 
> We have been following the Tbolt power discussions but what I am missing is 
>  the main problem with Tbolts. All the power work will not improve the 
> frequency  performance of the unit because the frequency is constantly 
> changed 
> to correct  time. Tbolt is an excellent time device but not good for 
> frequency reference  past 1E-10. I noticed it when I bought it and compared 
> it with 
> my Tracor 527E on  the needle and ever since used an Austron 2110 with a 
> digital 100 sec. loop for  clean up. My Swiss partner Juerg has relied on an 
> OSA F3 for Tbolt clean up but  continuous bad results on our work 

Re: [time-nuts] 10Mhz TXCO for LTE-Lite?

[paul swed]

Jim
Its always just around the corner type of project.
The unit works well enough. I have the 20 MHz version. So the plan sort of
doesn't happen. That would be to add a small OCXO. Call it lazy.
Paul
WB8TSL

On Fri, Sep 2, 2016 at 9:44 AM, Jim Miller  wrote:

> Did anyone implement an external 10Mhz TXCO for the Jackson-Labs LTE Lite?
>
> I'm finally getting around to trying to get 10Mhz out of this with a low
> enough impedance to drive a 50ohm cable.
>
> Thanks
>
> jim ab3cv
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Re: [time-nuts] What's the best Windows 10 ntp client?

[robkimberley]

I use the Windows NTP available on the Meinberg web site. Works well with 
Win10. In conjunction wuth their NTP Monitor it's a great combination. Rob


Sent from my Samsung Galaxy smartphone.
 Original message From: Mark Sims  Date: 
02/09/2016  18:04  (GMT+00:00) To: time-nuts@febo.com Subject: [time-nuts] 
What's the best Windows 10 ntp client? 
You never said what accuracy you need for your time.   Lady Heather's time set 
function should get you down to the 40 msec area.  You can configure it to set 
the time once,  periodically, or whenever receiver time and system time diverge 
by "x" milliseconds.    The time set is a "jam sync" of the system clock, so no 
fancy pants long term smoothing or guarantees of a monotonically increasing 
system clock.

The next release of Lady Heather has improved the time functions and uses 
default values of the measured offset from when the GPS receiver time message 
arrives and the time in the message for many different types of receivers.   Or 
you can set the offset value to your own.  It also has the ability to measure 
the receiver message offset (best done on a Linux box with a good NTP 
implementation but you could use Lady Heather to sync the Windows time and then 
have it measure the receiver message offset)
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Re: [time-nuts] What's the best Windows 10 ntp client?

[Oz-in-DFW]

On 9/2/2016 1:29 AM, Dr. David Kirkby wrote:
> At my amateur radio club we have Internet access via a WiFi dongle with a Pay 
> As You Go card. A Windows 10 PC is only powered up while we are there, so on 
> around 2-4 hours per week. 
>
> Does anyone have any thoughts on what might be the most suitable software to 
> run on our Windows 10 PC to set the time correct? 
>
> Someone installed "Dimension 4" 
>
> http://www.thinkman.com/dimension4/
>
> As far as I can see, this takes the time from one single NTP server, which I 
> believe is not a good idea.  However,  given we only run the PC on 2-4 hours 
> per week,  maybe no ntp client will work well,  but I would have thought 
> using multiple servers being better than one. 
>
> I am wondering if anyone has any better suggestions for software. .
>
> Dave.
>


The key to my response is your (reasonable) request for "most suitable."

Given your scenario, I suspect the most demanding need for time is file
system coordination and possibly logging software time stamping. 
Operating on that assumption, and that you are running on a "WiFi
Dongle" which I suspect is actually a cellular data card, the native
syncing capability of Win10 combined with the PC's real time clock is
probably more than adequate. It's also probably going to be more
economical as it will be considerably less 'chatty' that serious NTP
clients.

I know this doesn't meet the standards of time-nuttery, but it's
probably more than adequate for this particular application. 

Oz (N1OZ, in DFW) standing next to the fire extinguisher.

-- 
mailto:o...@ozindfw.net
Oz
POB 93167 
Southlake, TX 76092 (Near DFW Airport) 



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Re: [time-nuts] Tbolt issues

[Bob kb8tq]

Hi

Just to be a bit more clear:

This is *not* something unique to the Tbolt. It shows up on all GPSDO's. There 
have been a lot of posts with data plots showing this on lots of GPSDO's. The 
issue is more basic than a goof in a control loop setting. To some extent it is 
a problem on all frequency sources. GPSDO's just happen to get looked at more 
often.

Bob

> On Sep 2, 2016, at 1:11 PM, Mark Sims  wrote:
> 
> If you don't like how the Tbolt adjusts the oscillator on your Tbolt... do it 
> yourself.   You can set up the Tbolt for manual DAC control and implement 
> your own control loop.   Warren Sarkison and I implemented a alternate 
> control PID for the Tbolt DAC.   Yep,  it's in Lady Heather.  It's been a 
> while since I've played with it.   I seem to remember people getting down 
> close to the 1E-13 range.
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Re: [time-nuts] What's the best Windows 10 ntp client?

[David J Taylor]

From: Cube Central

I would like to retract my previous statement.  If you are only using the 
Windows system a couple hours a week, that may not be enough time for you to 
see any benefit from using NTP.


NTP needs more time than that to "discuss" the local system time with the 
other configured NTP servers out there on the Internet.  (and you would want 
more than a single server in the configuration file)

[]
-Randal
=

Randal,

Take a look at PC Puffin's timekeeping here:

 http://www.satsignal.eu/mrtg/performance_puffin.php

It is switched on every morning, and is within a couple of milliseconds 
almost immediately.  It runs Win-10 which helps (as would Win-8), and syncs 
to stratum-1 servers on my LAN.  Some of those servers are Raspberry Pi 
cards with a low-cost GPS/PPS, running continuously - possibly another 
interesting project for the radio club, together with using the RPi and an 
RTL dongle as a receiver between 50 and 1500 MHz.


Using the "pool" directive ensures that NTP has enough servers without 
having to edit any configuration file for specific servers.


Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 


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[time-nuts] Tbolt issues

[Mark Sims]

If you don't like how the Tbolt adjusts the oscillator on your Tbolt... do it 
yourself.   You can set up the Tbolt for manual DAC control and implement your 
own control loop.   Warren Sarkison and I implemented a alternate control PID 
for the Tbolt DAC.   Yep,  it's in Lady Heather.  It's been a while since I've 
played with it.   I seem to remember people getting down close to the 1E-13 
range.
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[time-nuts] What's the best Windows 10 ntp client?

[Mark Sims]

You never said what accuracy you need for your time.   Lady Heather's time set 
function should get you down to the 40 msec area.  You can configure it to set 
the time once,  periodically, or whenever receiver time and system time diverge 
by "x" milliseconds.The time set is a "jam sync" of the system clock, so no 
fancy pants long term smoothing or guarantees of a monotonically increasing 
system clock.

The next release of Lady Heather has improved the time functions and uses 
default values of the measured offset from when the GPS receiver time message 
arrives and the time in the message for many different types of receivers.   Or 
you can set the offset value to your own.  It also has the ability to measure 
the receiver message offset (best done on a Linux box with a good NTP 
implementation but you could use Lady Heather to sync the Windows time and then 
have it measure the receiver message offset)
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Re: [time-nuts] What's the best Windows 10 ntp client?

[Chris Albertson]

The best NTP program to run is the reference implementation at ntp.org
This is the one all the experts are looking at and fixing when problems or
improvements are found.   ftp.org also on their download page as a link to
third party parts and re-implementatons for those who for whatever reason
can't use the official release from ntp.org.  This is the same software
that almost all of the NTP servers out on the Internet are running.

You are right about using just one NTP server for time.  I'd suggest a
minimum of three but it cost not more to use five.  NTP will figure out
which of them are "best" from the set you get it.

What kind of accuracy do you need?   I assume if the computer is running
Windows 10 all you need is the nominal time to maybe 1/10th of a second at
best.That is 100 milliseconds and is dead-easy such that even MS
Windows with a poor internet connection can work at that level.   You
should be able to get to tens of milliseconds.

With effort the above software from ntp.org can run at the few micro
seconds level.  That should be within the means of any radio club but you
may not need it.   It would involve putting up a GPS antenna, running coax
to a GPS receiver.  Nothing a bunch of hams could not handle but you may
only need 30 to 50 millisecond accuracy and Windows can do using poll
servers on the Internet.

All that said,  You MAY already have a good NTP server running at your
site.  Many home routers run NTP inside and are left on and running 24x7.
The router uses ntp just to get the time of the log files correct and
likely does this bater then MS Windows.   If you have a local ntp server
then using just one server (the local one) is fine.



On Thu, Sep 1, 2016 at 11:29 PM, Dr. David Kirkby 
wrote:

> At my amateur radio club we have Internet access via a WiFi dongle with a
> Pay As You Go card. A Windows 10 PC is only powered up while we are there,
> so on around 2-4 hours per week.
>
> Does anyone have any thoughts on what might be the most suitable software
> to run on our Windows 10 PC to set the time correct?
>
> Someone installed "Dimension 4"
>
> http://www.thinkman.com/dimension4/
>
> As far as I can see, this takes the time from one single NTP server, which
> I believe is not a good idea.  However,  given we only run the PC on 2-4
> hours per week,  maybe no ntp client will work well,  but I would have
> thought using multiple servers being better than one.
>
> I am wondering if anyone has any better suggestions for software. .
>
> Dave.
> ___
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>



-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] What's the best Windows 10 ntp client?

[Cube Central]

I would like to retract my previous statement.  If you are only using the 
Windows system a couple hours a week, that may not be enough time for you to 
see any benefit from using NTP.

NTP needs more time than that to "discuss" the local system time with the other 
configured NTP servers out there on the Internet.  (and you would want more 
than a single server in the configuration file)

I don't see why the built-in Windows Time service wouldn't work in this 
instance.  It should be able to reach out to a (single, pre-configured) source 
and set the time within a couple of seconds.

Is the PC powering on with the incorrect time consistently?  If this is the 
case, then it may require a new CMOS battery.  (A small, coin battery that 
helps the computer keep its configuration and time while off)

Additionally, it sounds as if Internet access is a precious commodity for you, 
so every little bit of data sent or received is precious.  The built-in Windows 
Time service would use less data to simply set the system time than NTP does.  
Also, I believe, it is configured not to trigger a "dial on demand" request 
that would connect to the Internet on its own.  I am not sure this is the case 
with the NTP solution.

It is hard to say which implementation is the ideal one for you, as you didn't 
state how important the correct time is to you or your club.  If you need the 
correct time "good enough" then use the built-in Windows Time service that uses 
SNTP.  If you need more exact time than that, well perhaps some other clock 
would be better used.  Such as this:  
https://www.tindie.com/products/ptudor/jemma-clock/  ... or any number of other 
variants.  The combination of GPS and a clock or display is very powerful 
indeed and very easy to set up and use.

I hope that some of this helps.

-Randal
(at CubeCentral)


-Original Message-
From: Cube Central [mailto:cubecent...@gmail.com] 
Sent: Friday, 02 September, 2016 08:04
To: 'Discussion of precise time and frequency measurement' 
Subject: RE: [time-nuts] What's the best Windows 10 ntp client?

I would also suggest using NTP.  I have set it up and configured it using the 
directions here (  http://www.satsignal.eu/ntp/setup.html ) and it works very 
well.  

One thing to note is that Windows 10 does have the built in capability to set 
the time for itself, using a variant of SNTP.   So I would be sure to turn this 
off by disabling the "Windows Time" Service.

Also, be aware that using NTP on a system that isn't on all the time, or has 
what I would describe as "asymmetric internet access" might cause NTP to be 
slow in correcting the time, or only be somewhat effective.  If you are only 
looking to have it accurate to the right minute, then don't worry.  But this is 
better addressed elsewhere.

-Randal
(at CubeCentral)

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dr. David 
Kirkby
Sent: Friday, 02 September, 2016 00:30
To: Discussion of precise time and frequency measurement 
Subject: [time-nuts] What's the best Windows 10 ntp client?

At my amateur radio club we have Internet access via a WiFi dongle with a Pay 
As You Go card. A Windows 10 PC is only powered up while we are there, so on 
around 2-4 hours per week. 

Does anyone have any thoughts on what might be the most suitable software to 
run on our Windows 10 PC to set the time correct? 

Someone installed "Dimension 4" 

http://www.thinkman.com/dimension4/

As far as I can see, this takes the time from one single NTP server, which I 
believe is not a good idea.  However,  given we only run the PC on 2-4 hours 
per week,  maybe no ntp client will work well,  but I would have thought using 
multiple servers being better than one. 

I am wondering if anyone has any better suggestions for software. .

Dave.
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Re: [time-nuts] What's the best Windows 10 ntp client?

[Cube Central]

I would also suggest using NTP.  I have set it up and configured it using the 
directions here (  http://www.satsignal.eu/ntp/setup.html ) and it works very 
well.  

One thing to note is that Windows 10 does have the built in capability to set 
the time for itself, using a variant of SNTP.   So I would be sure to turn this 
off by disabling the "Windows Time" Service.

Also, be aware that using NTP on a system that isn't on all the time, or has 
what I would describe as "asymmetric internet access" might cause NTP to be 
slow in correcting the time, or only be somewhat effective.  If you are only 
looking to have it accurate to the right minute, then don't worry.  But this is 
better addressed elsewhere.

-Randal
(at CubeCentral)

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dr. David 
Kirkby
Sent: Friday, 02 September, 2016 00:30
To: Discussion of precise time and frequency measurement 
Subject: [time-nuts] What's the best Windows 10 ntp client?

At my amateur radio club we have Internet access via a WiFi dongle with a Pay 
As You Go card. A Windows 10 PC is only powered up while we are there, so on 
around 2-4 hours per week. 

Does anyone have any thoughts on what might be the most suitable software to 
run on our Windows 10 PC to set the time correct? 

Someone installed "Dimension 4" 

http://www.thinkman.com/dimension4/

As far as I can see, this takes the time from one single NTP server, which I 
believe is not a good idea.  However,  given we only run the PC on 2-4 hours 
per week,  maybe no ntp client will work well,  but I would have thought using 
multiple servers being better than one. 

I am wondering if anyone has any better suggestions for software. .

Dave.
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Re: [time-nuts] What's the best Windows 10 ntp client?

[Tim Shoppa]

For a Windows machine that is always on, I would strongly recommend
Meinberg NTPD as "easy to install and the real deal". And free. It works
just fine under Windows 10.

Dimension 4, I am not impressed by, but if the only thing it has to do is
set the clock at boot time, then it might be OK. But I think Windows 10
time service is good enough to do that out-of-the box from Microsoft.

Tim N3QE

On Fri, Sep 2, 2016 at 2:29 AM, Dr. David Kirkby  wrote:

> At my amateur radio club we have Internet access via a WiFi dongle with a
> Pay As You Go card. A Windows 10 PC is only powered up while we are there,
> so on around 2-4 hours per week.
>
> Does anyone have any thoughts on what might be the most suitable software
> to run on our Windows 10 PC to set the time correct?
>
> Someone installed "Dimension 4"
>
> http://www.thinkman.com/dimension4/
>
> As far as I can see, this takes the time from one single NTP server, which
> I believe is not a good idea.  However,  given we only run the PC on 2-4
> hours per week,  maybe no ntp client will work well,  but I would have
> thought using multiple servers being better than one.
>
> I am wondering if anyone has any better suggestions for software. .
>
> Dave.
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[time-nuts] 10Mhz TXCO for LTE-Lite?

[Jim Miller]

Did anyone implement an external 10Mhz TXCO for the Jackson-Labs LTE Lite?

I'm finally getting around to trying to get 10Mhz out of this with a low
enough impedance to drive a 50ohm cable.

Thanks

jim ab3cv
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Re: [time-nuts] Tbolt issues

[Bert Kehren via time-nuts]

Charles,
 would you please share your settings, this is exactly what we are  looking 
for. We are doing it by trial and error but your expertise will help  
greatly.
English not being my native language linguistics are some time a  problem
Thanks 
Bert
 
 
In a message dated 9/1/2016 6:26:32 P.M. Eastern Daylight Time,  
csteinm...@yandex.com writes:

Bert  wrote:

> maybe some one smarter than us can working with the  parameters that Tbolt
> makes available better performance can be  achieved

I am quite sure of that

> the frequency is being  changed to compensate for time

Yes, the PPS is steered by making slight  adjustments to the OCXO 
frequency.  But you can make these  adjustments as arbitrarily small as 
you want with the setup  parameters.  I run my Tbolts with pretty tight 
limits on the  frequency adjustments.

> and we do not care about ADEV, we care  about the actual
> frequency at that moment it goes in to the measuring  device

There is no "there" there.  One never makes a frequency  measurement at 
just one instant -- the measurement will ALWAYS be done  over a macro 
time interval (very often, one second, sometimes 0.1, 10,  100, or 1000 
seconds).  We never observe, and have no way to know,  the instantaneous 
frequency (as you put it, "the actual frequency at that  moment it goes 
into the measuring device") -- so how can we care about  it?  The only 
thing relevant (or even meaningful) is the average  frequency during our 
measurement interval.

xDEV tells us half of  what we want to know -- how stable our oscillator 
is from one measurement  interval to another.  We would also like to know 
what frequency it is  wobbling around -- the "centroid" frequency, if you 
will (to borrow a  geometric term).  (Mathematicians can argue for days 
about which type  of "average" is appropriate here -- the rest of us just 
pick one and carry  on.)  ADEV does not tell us this "centroid" frequency 
directly, but  it can be extracted from the same measurements we took to 
calculate  ADEV.

I think you are being misled by a belief that the linguistic  construct, 
"instantaneous frequency," has real meaning in the world.   It doesn't.

Best  regards,

Charles


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Re: [time-nuts] Tbolt issues

[Bob kb8tq]

Hi

The GPSDO might have an ADEV of 1 ppt at 1 sec and that rises to 30 ppt at 100 
sec. It also might not, but let's use those numbers.

ADEV is a standard deviation. You can get an idea of the magnitude of the 
change reading to reading from it. It does not give you a sign for that change. 
In the case above, it is a good bet that you see strings of 1 sec data with 
mostly the same sign.  They have to add up to the 30X larger number when tau 
gets to 100 sec.

That creates a major problem if you just look at the 1 sec data. A "normal" 
frequency standard does not have a rise or bump like that in the ADEV plot. 
Thus the quick rule of thumb stuff falls apart. The correct way to do it will 
always be to work out what the noise process is and calculate based on it. That 
is not a popular thing to do 

Bob

> On Sep 2, 2016, at 6:38 AM, Lars Walenius  wrote:
> 
> Hello Bert,
> 
> For me your findings look very much the same as this:
> http://www.leapsecond.com/pages/tbolt-8d/ 
> At least for me I should say the (absolute) frequency accuracy for this Tbolt 
> is not better than +-1E10 with 1 or 10 seconds gate times on a counter. Maybe 
> I am totally wrong as both Tom and Charles says that your Tbolt is bad.
> 
> As Bob Camp said we need a confidence interval. For me in this case it is 
> peak values if they occur more than a couple of times. Think of  voltmeters. 
> If it is out of spec say for only a couple of hours but it happens several 
> times say during a month or year and the voltmeters is not considered bad I 
> should say change the spec. If I were going to use the Tbolt as a reference 
> in a production environment with a 1 or 10 sec gate time I probably would set 
> the internal spec to 2E-10.
> 
> If I understand correct the Tracor 527E has a low pass filter with a time 
> constant of 1second so the 1 second frequency average data should be relevant.
> 
> As I am also interested in frequency accuracy with GPSDO´s used with 
> frequency counters, I have a maybe far to simplistic rule of accuracy: (10x 
> the worst ADEV at all Taus longer than the gate time). So for the Tbolt with 
> time constant of 100 seconds it is a hump of about 1E-11 at 100seconds so at 
> gate times shorter than 100seconds I expect to see excursions up to 1E-10. If 
> you set the time constant to 1000seconds and the OCXO in the Thunderbolt is 
> good to 2 to 3E-12 all the way 1-1000 seconds you probably don´t have 
> excursions higher than 2 to 3E-11 at 1-100 seconds gate times.
> 
> Lars
> 
> 
> Från: Bert Kehren via time-nuts
> Skickat: den 1 september 2016 19:09
> 
> We have been following the Tbolt power discussions but what I am missing is 
>  the main problem with Tbolts. All the power work will not improve the 
> frequency  performance of the unit because the frequency is constantly 
> changed 
> to correct  time. Tbolt is an excellent time device but not good for 
> frequency reference  past 1E-10. I noticed it when I bought it and compared 
> it with 
> my Tracor 527E on  the needle and ever since used an Austron 2110 with a 
> digital 100 sec. loop for  clean up. My Swiss partner Juerg has relied on an 
> OSA F3 for Tbolt clean up but  continuous bad results on our work resulted in 
> a detailed analysis using a  HP53132A counter and M100, FTS44060, two 
> OSA8600's and one of the best FE405's.  The rsult is that the OSA F3 does not 
> clean up the Tbolt and we see +-4E-11  changes and old data shows even some 
> +-8 
> E-11 excursions. With the popularity of  the Tbolt an analog or digital 
> clean up loop would make sense. We are working on  both, the analog because I 
> saw similar behavior on the FE5680 and FE5650, we did  a GPSDO but do not 
> plan 
> on using those Rb's but focus on M100 and FRK. 
> The collective expertise of time nuts could make a significant  contribution
> For power in critical applications we use the excellent work from Bern Kaa  
> a friend for the last twenty years and well known because of his published 
> work  in the European HAM community
> Bert Kehren
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Re: [time-nuts] What's the best Windows 10 ntp client?

[Martin Burnicki]

Clay Autery wrote:
> NTP Time Server Monitor by Meinberg.

Sorry, no.

As the name suggests this is only a *monitor* program for NTP service
(ntpd). You can use it to start/stop the NTP service, have a graphical
presentation of the loopstats files optionally generated by ntpd, etc.

So this is a nice optional addon for ntpd, but you need ntpd to actually
synchronize the system time. The monitor program doesn't do that.

Martin (working @meinberg)

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Re: [time-nuts] Tbolt issues

[Bob kb8tq]

Hi

The gotcha in your approach is that you are using more than one sample out of 
the system to get frequency. Thus you are measuring over a time period. To get 
instantaneous frequency you need to base it on a single sample. There are some 
other restrictions (infinite bandwidth being the big one). 

Bob

> On Sep 2, 2016, at 2:25 AM, Bill Byrom  wrote:
> 
> The problem is that "frequency" has more than one meaning. The main
> dictionary definitions have to do with the frequency of occurrence of
> some items in a category with respect to a larger set, or the frequency
> of occurrence of some repeating event per unit of time. But we also use
> mathematical representations of waveforms containing a "frequency" or
> "angular frequency" parameter, and we can also define waveforms where
> the frequency parameter is itself a function over time. In these cases
> there obviously is an instantaneous frequency which for example
> represents the value of f at a particular value of t in sin(2 pi f t),
> where f = somefunction(t).
> 
> So you have discrete events (a rising edge, or the positive zero
> crossing of a sinusoidal waveform) which define a "frequency" property
> which only has meaning when we compare the time values of at least two
> of these events, but we also have an equation defining a sinewave, where
> the instantaneous angular frequency describes the derivative of the
> phase change vs time. You have to consider continuous as well as
> discrete systems.
> 
> In modern modulation theory the concept of vector modulation is used.
> This involves a carrier wave frequency and amplitude, then I/Q or vector
> modulation which instantaneously varies the amplitude (vector length)
> and phase (vector angle) of the signal. For a constant amplitude signal,
> the derivative of the vector modulation phase (arctangent of the I/Q
> ratio) corresponds to the instantaneous frequency.
> 
> At work I deal with equipment which generates RF signal using a 50 GS/s
> maximum sampling rate D/A converter, which provides one sample every 20
> ps. I can create a linear frequency up-chirp using this instrument with
> a frequency modulation slope of 2 MHz per us (microsecond) at a center
> frequency of 1 GHz. So there are 50,000 D/A samples each us, and
> although the average frequency over that us is 1 GHz (50 D/A
> samples/cycle), the start of the chirp is at 999 MHz (about 50.05 D/A
> samples/cycle) while the end of the chirp 1 us later is at 1001 MHz
> (about 49.95 D/A samples/cycle). In this case, the value of
> somefunction(T0 - 1 us) = 999 MHz and somefunction(T0 + 1 us) = 1001
> MHz, where T0 is the time at the middle of the chirp. There are
> obviously not an integral number of D/A samples per sinewave cycle, but
> that is no problem. The D/A has 10 bits of resolution and is not
> perfect, and the combination of jitter and other errors produces
> wideband noise and spurs smeared over the frequency range of DC to the
> Nyquist rate, but these errors are very small (many 10's of dB down from
> the desired signal).
> 
> The signal I just described creates the 2 MHz chirp in a 1 us time
> interval using 50,000 D/A samples. The 10-bit resolution voltage values
> of each of those samples (spaced by 20 ps) select the closest D/A values
> which represent the sine function with an "instantaneous frequency"
> given by somefunction (which in this case is a linear ramp). So you can
> think of this as a discrete system which is changing the instantaneous
> frequency every 20 ps (with instrument errors due to the limited 10-bit
> voltage resolution, amplitude errors, jitter errors, and errors from
> other sources).
> 
> On the measurement side, I have an instrument with a 16-bit 400 MS/s A/D
> which can sample a superheterodyne downconverted signal at an IF
> frequency over a 165 MHz span. Those samples are run through a DDC
> (digital downconverter using a Hilbert filter) to create two 200 MS/s
> streams (I and Q waveforms). For the example above, the 1 us 2 MHz wide
> linear chirp is sampled with 200 I/Q points, and calculating the
> derivative (slope) of the phase - which is arctangent(I/Q) - results in
> a frequency vs time trace. So the instantaneous frequency can be
> measured with 5 ns resolution (1/200 MS/s I/Q rate) in time across that
> 1 us wide frequency chirp.
> 
> So yes, the concept of "instantaneous frequency" is valid and is used
> everyday in many practical measurements on phase locked loop frequency
> synthesizers, radars, testing Bluetooth FSK transmitters, and for many
> other applications.
> 
> --
> Bill Byrom N5BB
> 
> 
> 
>> On Thu, Sep 1, 2016, at 10:39 PM, jimlux wrote:
>>> On 9/1/16 5:51 PM, Charles Steinmetz wrote:
>>> Nick wrote:
>>> 
 On a theoretical basis, can one speak of the limit of the frequency
 observed as tau approaches zero?
 Might that in some way be the "instantaneous frequency" which people
 often think of?
>>> 
>>> That is (or is "something like") what 

Re: [time-nuts] What's the best Windows 10 ntp client?

[Clay Autery]

NTP Time Server Monitor by Meinberg.

__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389

On 9/2/2016 1:29 AM, Dr. David Kirkby wrote:
> At my amateur radio club we have Internet access via a WiFi dongle with a Pay 
> As You Go card. A Windows 10 PC is only powered up while we are there, so on 
> around 2-4 hours per week. 
>
> Does anyone have any thoughts on what might be the most suitable software to 
> run on our Windows 10 PC to set the time correct? 
>
> Someone installed "Dimension 4" 
>
> http://www.thinkman.com/dimension4/t
>
> As far as I can see, this takes the time from one single NTP server, which I 
> believe is not a good idea.  However,  given we only run the PC on 2-4 hours 
> per week,  maybe no ntp client will work well,  but I would have thought 
> using multiple servers being better than one. 
>
> I am wondering if anyone has any better suggestions for software. .
>
> Dave.
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Re: [time-nuts] What's the best Windows 10 ntp client?

[Martin Burnicki]

Dr. David Kirkby wrote:
> At my amateur radio club we have Internet access via a WiFi dongle with a Pay 
> As You Go card. A Windows 10 PC is only powered up while we are there, so on 
> around 2-4 hours per week. 
> 
> Does anyone have any thoughts on what might be the most suitable software to 
> run on our Windows 10 PC to set the time correct? 

It depends on the accuracy requirements you have. Getting high accuracy
under Windows can be pretty tricky.

Some days ago tvb asked me off-list about details on timekeeping under
different Windows versions, and I've put some information together here:
https://www.meinbergglobal.com/download/burnicki/time_synchronization_accuracy_with_ntp.pdf

I've also put some measurement results together, which you can find here:
https://www.meinbergglobal.com/download/burnickintp_and_windows_history.pdf

These articles are PDF exports from Meinberg-internal wiki pages, so
they may not be particularly well formatted. Sorry for that.

> Someone installed "Dimension 4" 
> 
> http://www.thinkman.com/dimension4/

I've never tried this.

> As far as I can see, this takes the time from one single NTP server, which I 
> believe is not a good idea.  However,  given we only run the PC on 2-4 hours 
> per week,  maybe no ntp client will work well,  but I would have thought 
> using multiple servers being better than one. 
> 
> I am wondering if anyone has any better suggestions for software. .

Again, it depends on the accuracy requirements you have. The NTP daemon
(ntpd) from ntp.org has been designed for long-term operation. It tries
to determine the clock drift of the local computer, and compensate it.

The Windows port also includes a couple of workarounds for limitations
in the Windows kernel, and IMO yields very good results under the given
conditions.

Martin

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Re: [time-nuts] Tbolt issues

[Lars Walenius]

Hello Tom,

What are the conditions for your charts? Are the Tbolts in locked condition or 
holdover? If locked what settings do you have for time constant and damping? Is 
it any other setting that is important?

For the frequency chart I see excursions up to +-3E-11 so not so far from the 
values that Bert gives and as I understand his TBolt might have a default 
setting of 100 seconds.

Lars


Från: Tom Van Baak
Skickat: den 1 september 2016 21:12


Hi Bert,

> because the frequency is constantly changed to correct  time.

A simple answer: you may have a bad TBolt. Was it part of the TAPR group buy, 
or did you buy it from eBay/China? If TAPR, you get a free replacement. Contact 
me off-list.

> Tbolt is an excellent time device but not good for frequency reference  past 
> 1E-10.

No, again it sounds like you have a bad TBolt. Or something is wrong (antenna? 
reception? time constant? environment? China resoldered parts?). I appreciate 
that Juerg did lots of testing -- do you happen to have his ADEV plot?

I'm willing to help you debug this.

(1) Attached is the ADEV of 8 random TBolts that I tested recently. How does 
this compare to yours? You can see mine are all under 2e-12 at 1 s and under 
4e-12 at 100 s. On a bad day during holdover it might climb to 1e-11 at 1000 s 
but when locked GPS disciplining takes over and keeps it down to 2 or 3e-12.

(2) For locked vs. unlocked TBolt ADEV, see 
http://www.leapsecond.com/pages/gpsdo/

(3) Also attached is a frequency plot showing the typical noise and wander, 
down at the 1e-11 level. How does this compare with yours?

Your claim of 1e-10 is order(s) of magnitude worse than the TBolts that I see. 
Something is wrong.

/tvb

- Original Message -
From: "Bert Kehren via time-nuts" 
To: 
Sent: Thursday, September 01, 2016 9:54 AM
Subject: [time-nuts] Tbolt issues


> We have been following the Tbolt power discussions but what I am missing is
> the main problem with Tbolts. All the power work will not improve the
> frequency  performance of the unit because the frequency is constantly changed
> to correct  time. Tbolt is an excellent time device but not good for
> frequency reference  past 1E-10. I noticed it when I bought it and compared 
> it with
> my Tracor 527E on  the needle and ever since used an Austron 2110 with a
> digital 100 sec. loop for  clean up. My Swiss partner Juerg has relied on an
> OSA F3 for Tbolt clean up but  continuous bad results on our work resulted in
> a detailed analysis using a  HP53132A counter and M100, FTS44060, two
> OSA8600's and one of the best FE405's.  The rsult is that the OSA F3 does not
> clean up the Tbolt and we see +-4E-11  changes and old data shows even some 
> +-8
> E-11 excursions. With the popularity of  the Tbolt an analog or digital
> clean up loop would make sense. We are working on  both, the analog because I
> saw similar behavior on the FE5680 and FE5650, we did  a GPSDO but do not plan
> on using those Rb's but focus on M100 and FRK.
> The collective expertise of time nuts could make a significant  contribution
> For power in critical applications we use the excellent work from Bern Kaa
> a friend for the last twenty years and well known because of his published
> work  in the European HAM community
> Bert Kehren
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Re: [time-nuts] Tbolt issues

[Lars Walenius]

Hello Bert,

For me your findings look very much the same as this:
http://www.leapsecond.com/pages/tbolt-8d/ 
At least for me I should say the (absolute) frequency accuracy for this Tbolt 
is not better than +-1E10 with 1 or 10 seconds gate times on a counter. Maybe I 
am totally wrong as both Tom and Charles says that your Tbolt is bad.

As Bob Camp said we need a confidence interval. For me in this case it is peak 
values if they occur more than a couple of times. Think of  voltmeters. If it 
is out of spec say for only a couple of hours but it happens several times say 
during a month or year and the voltmeters is not considered bad I should say 
change the spec. If I were going to use the Tbolt as a reference in a 
production environment with a 1 or 10 sec gate time I probably would set the 
internal spec to 2E-10.

If I understand correct the Tracor 527E has a low pass filter with a time 
constant of 1second so the 1 second frequency average data should be relevant.

As I am also interested in frequency accuracy with GPSDO´s used with frequency 
counters, I have a maybe far to simplistic rule of accuracy: (10x the worst 
ADEV at all Taus longer than the gate time). So for the Tbolt with time 
constant of 100 seconds it is a hump of about 1E-11 at 100seconds so at gate 
times shorter than 100seconds I expect to see excursions up to 1E-10. If you 
set the time constant to 1000seconds and the OCXO in the Thunderbolt is good to 
2 to 3E-12 all the way 1-1000 seconds you probably don´t have excursions higher 
than 2 to 3E-11 at 1-100 seconds gate times.

Lars


Från: Bert Kehren via time-nuts
Skickat: den 1 september 2016 19:09

We have been following the Tbolt power discussions but what I am missing is 
 the main problem with Tbolts. All the power work will not improve the 
frequency  performance of the unit because the frequency is constantly changed 
to correct  time. Tbolt is an excellent time device but not good for 
frequency reference  past 1E-10. I noticed it when I bought it and compared it 
with 
my Tracor 527E on  the needle and ever since used an Austron 2110 with a 
digital 100 sec. loop for  clean up. My Swiss partner Juerg has relied on an 
OSA F3 for Tbolt clean up but  continuous bad results on our work resulted in 
a detailed analysis using a  HP53132A counter and M100, FTS44060, two 
OSA8600's and one of the best FE405's.  The rsult is that the OSA F3 does not 
clean up the Tbolt and we see +-4E-11  changes and old data shows even some +-8 
E-11 excursions. With the popularity of  the Tbolt an analog or digital 
clean up loop would make sense. We are working on  both, the analog because I 
saw similar behavior on the FE5680 and FE5650, we did  a GPSDO but do not plan 
on using those Rb's but focus on M100 and FRK. 
The collective expertise of time nuts could make a significant  contribution
For power in critical applications we use the excellent work from Bern Kaa  
a friend for the last twenty years and well known because of his published 
work  in the European HAM community
Bert Kehren
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Re: [time-nuts] What's the best Windows 10 ntp client?

[David J Taylor]

From: STR .

https://www.meinbergglobal.com/english/sw/ntp.htm

It uses NTP and you can set the servers you like in its (typically) 
C:\Program Files (x86)\NTP\etc \ntp.conf

===

As I mention here:

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

it is suggested that the program be installed outside the Program Files tree 
so that user edits to ntp.conf don't fall into the Windows directory 
virtualisation trap - "I edited the file but nothing changed".  No need for 
admin-level access.


Cheers,
David

--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 


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Re: [time-nuts] What's the best Windows 10 ntp client?

[STR .]

https://www.meinbergglobal.com/english/sw/ntp.htm

It uses NTP and you can set the servers you like in its (typically) C:\Program 
Files (x86)\NTP\etc \ntp.conf


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of David J Taylor
Sent: Friday, September 2, 2016 1:18 PM
To: Discussion of precise time and frequency measurement 
Subject: Re: [time-nuts] What's the best Windows 10 ntp client?

At my amateur radio club we have Internet access via a WiFi dongle with a Pay 
As You Go card. A Windows 10 PC is only powered up while we are there, so on 
around 2-4 hours per week.

Does anyone have any thoughts on what might be the most suitable software to 
run on our Windows 10 PC to set the time correct?

Someone installed "Dimension 4"

http://www.thinkman.com/dimension4/

As far as I can see, this takes the time from one single NTP server, which I 
believe is not a good idea.  However,  given we only run the PC on 2-4 hours 
per week,  maybe no ntp client will work well,  but I would have thought using 
multiple servers being better than one.

I am wondering if anyone has any better suggestions for software. .

Dave.
___


Why not use the reference implementation - here for Windows:

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

Works with the NTP Pool selecting multiple servers.  For modes requiring better 
than 0.1 seconds accuracy consider adding a GPS/PPS to the PC. 
Performance available with NTP:

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

73,
David GM8ARV
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 

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Re: [time-nuts] Tbolt issues

[Charles Steinmetz]

Jim wrote:


Instantaneous frequency does have a theoretical meaning, even if not
measureable..

If I'm processing  a linear frequency chirp, I can say that the
frequency at time t is some (f0 + t*slope).  the frequency at time
t+epsilon is different, as is the frequency at time t-epsilon.


Strictly speaking, the chirp does not have a frequency, at any time -- 
it has a *spectrum*.  We use the mathematical fiction of "instantaneous 
frequency" to express the limit as we differentiate.  This is the same 
as the use of the term in connection with FM modulation, and it is an 
abstraction -- not something real in the world (which is why it is not 
measurable, not only as a practical matter, but even in principle.)


Best regards,

Charles


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Re: [time-nuts] What's the best Windows 10 ntp client?

[David J Taylor]

At my amateur radio club we have Internet access via a WiFi dongle with a 
Pay As You Go card. A Windows 10 PC is only powered up while we are there, 
so on around 2-4 hours per week.


Does anyone have any thoughts on what might be the most suitable software to 
run on our Windows 10 PC to set the time correct?


Someone installed "Dimension 4"

http://www.thinkman.com/dimension4/

As far as I can see, this takes the time from one single NTP server, which I 
believe is not a good idea.  However,  given we only run the PC on 2-4 hours 
per week,  maybe no ntp client will work well,  but I would have thought 
using multiple servers being better than one.


I am wondering if anyone has any better suggestions for software. .

Dave.
___


Why not use the reference implementation - here for Windows:

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

Works with the NTP Pool selecting multiple servers.  For modes requiring 
better than 0.1 seconds accuracy consider adding a GPS/PPS to the PC. 
Performance available with NTP:


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

73,
David GM8ARV
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 


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Re: [time-nuts] Tbolt issues

[Gregory Maxwell]

On Fri, Sep 2, 2016 at 12:51 AM, Charles Steinmetz
 wrote:
> Now shorten the observation time to 20nS.  We see 1/5 of a complete cycle
> (72 degrees, 0.4 pi radians) of the wave.  No matter which particular 72
> degrees we see, we simply don't have enough information to reliably deduce

I do not see why you argue that.

For the purpose of discussion, lets assume you have a noiseless signal
which is stationary in frequency and amplitude over 20nS starting at
the zero crossing. Given these strong priors (single tone, constant
frequency which is not higher than one half cycle in our 20nS window,
constant amplitude, noiseless) there is exactly one frequency
consistent with any of those two observations.  If the starting phase
is unknown, I believe you need one additional observation to end up
over-determined and have an unambiguous solution again.

This kind of strong prior assumption is why sinusoidal estimators and
PLLs are able to extract tones with precision far beyond what you
would expect from taking a DFT from equivalent amount of data.

In reality, there is phase noise, non-linearities, harmonics, tidal
variations, and whatnot that make these assumptions untrue... but how
far they corrupt these assumptions depends on how useless the results
are.
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[time-nuts] What's the best Windows 10 ntp client?

[Dr. David Kirkby]

At my amateur radio club we have Internet access via a WiFi dongle with a Pay 
As You Go card. A Windows 10 PC is only powered up while we are there, so on 
around 2-4 hours per week. 

Does anyone have any thoughts on what might be the most suitable software to 
run on our Windows 10 PC to set the time correct? 

Someone installed "Dimension 4" 

http://www.thinkman.com/dimension4/

As far as I can see, this takes the time from one single NTP server, which I 
believe is not a good idea.  However,  given we only run the PC on 2-4 hours 
per week,  maybe no ntp client will work well,  but I would have thought using 
multiple servers being better than one. 

I am wondering if anyone has any better suggestions for software. .

Dave.
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Re: [time-nuts] Tbolt issues

[Bill Byrom]

The problem is that "frequency" has more than one meaning. The main
dictionary definitions have to do with the frequency of occurrence of
some items in a category with respect to a larger set, or the frequency
of occurrence of some repeating event per unit of time. But we also use
mathematical representations of waveforms containing a "frequency" or
"angular frequency" parameter, and we can also define waveforms where
the frequency parameter is itself a function over time. In these cases
there obviously is an instantaneous frequency which for example
represents the value of f at a particular value of t in sin(2 pi f t),
where f = somefunction(t).

So you have discrete events (a rising edge, or the positive zero
crossing of a sinusoidal waveform) which define a "frequency" property
which only has meaning when we compare the time values of at least two
of these events, but we also have an equation defining a sinewave, where
the instantaneous angular frequency describes the derivative of the
phase change vs time. You have to consider continuous as well as
discrete systems.

In modern modulation theory the concept of vector modulation is used.
This involves a carrier wave frequency and amplitude, then I/Q or vector
modulation which instantaneously varies the amplitude (vector length)
and phase (vector angle) of the signal. For a constant amplitude signal,
the derivative of the vector modulation phase (arctangent of the I/Q
ratio) corresponds to the instantaneous frequency.

At work I deal with equipment which generates RF signal using a 50 GS/s
maximum sampling rate D/A converter, which provides one sample every 20
ps. I can create a linear frequency up-chirp using this instrument with
a frequency modulation slope of 2 MHz per us (microsecond) at a center
frequency of 1 GHz. So there are 50,000 D/A samples each us, and
although the average frequency over that us is 1 GHz (50 D/A
samples/cycle), the start of the chirp is at 999 MHz (about 50.05 D/A
samples/cycle) while the end of the chirp 1 us later is at 1001 MHz
(about 49.95 D/A samples/cycle). In this case, the value of
somefunction(T0 - 1 us) = 999 MHz and somefunction(T0 + 1 us) = 1001
MHz, where T0 is the time at the middle of the chirp. There are
obviously not an integral number of D/A samples per sinewave cycle, but
that is no problem. The D/A has 10 bits of resolution and is not
perfect, and the combination of jitter and other errors produces
wideband noise and spurs smeared over the frequency range of DC to the
Nyquist rate, but these errors are very small (many 10's of dB down from
the desired signal).

The signal I just described creates the 2 MHz chirp in a 1 us time
interval using 50,000 D/A samples. The 10-bit resolution voltage values
of each of those samples (spaced by 20 ps) select the closest D/A values
which represent the sine function with an "instantaneous frequency"
given by somefunction (which in this case is a linear ramp). So you can
think of this as a discrete system which is changing the instantaneous
frequency every 20 ps (with instrument errors due to the limited 10-bit
voltage resolution, amplitude errors, jitter errors, and errors from
other sources).

On the measurement side, I have an instrument with a 16-bit 400 MS/s A/D
which can sample a superheterodyne downconverted signal at an IF
frequency over a 165 MHz span. Those samples are run through a DDC
(digital downconverter using a Hilbert filter) to create two 200 MS/s
streams (I and Q waveforms). For the example above, the 1 us 2 MHz wide
linear chirp is sampled with 200 I/Q points, and calculating the
derivative (slope) of the phase - which is arctangent(I/Q) - results in
a frequency vs time trace. So the instantaneous frequency can be
measured with 5 ns resolution (1/200 MS/s I/Q rate) in time across that
1 us wide frequency chirp.

So yes, the concept of "instantaneous frequency" is valid and is used
everyday in many practical measurements on phase locked loop frequency
synthesizers, radars, testing Bluetooth FSK transmitters, and for many
other applications.

--
Bill Byrom N5BB



On Thu, Sep 1, 2016, at 10:39 PM, jimlux wrote:
> On 9/1/16 5:51 PM, Charles Steinmetz wrote:
>> Nick wrote:
>>
>>> On a theoretical basis, can one speak of the limit of the frequency
>>> observed as tau approaches zero?
>>> Might that in some way be the "instantaneous frequency" which people
>>> often think of?
>>
>> That is (or is "something like") what it **would** be, but a little
>> thought experiment will show that (and why) the linguistic
>> construction
>> is meaningless.
>>
>> The period of a 10MHz sine wave is 100nS.  Think about observing
>> it over
>> shorter and shorter (but still finite) time intervals.
>>
>> When the time interval is 100nS, we see one complete cycle (360
>> degrees,
>> 2 pi radians) of the wave.  At this point we still have **some**
>> shot at
>> deducing its frequency, because no matter at what phase we
>> start, we are
>> guaranteed to observe two peaks (one