Re: [time-nuts] Generating a solid PPS from 10Mhz source

[Magnus Danielson]

Attila,

On 01/20/2016 03:21 PM, Attila Kinali wrote:

On Wed, 20 Jan 2016 14:13:11 +
"Poul-Henning Kamp"  wrote:


The test results showed a quite more
detailed structure with few delays over 100ps and most being between
20ps and 80ps. Interestingly, some were close to 0ps, for which
we have no explanation good explanation.


Any on-chip PLL's with "spread-spectrum" to fudge EMI tests ?


Nope, the cyclone4 PLLs do not support spread spectrum.
Also, the 0ps positions were stable (suggesting some FPGA
internal feature to be the cause), but they weren't evenly
spread over the delay chain.


The timing report and estimator is just to make sure that a synchron 
design will work. The type of jitter/noise that you see is kind of 
typical. It's not that I don't like FPGA, I love it, but I just don't 
trust it for precision timing like that.


Cheers,
Magnus
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Re: [time-nuts] HP 5372A advice

[Magnus Danielson]

Hi Morris,

On 01/20/2016 09:59 AM, Morris Odell wrote:

Thanks very much for your reply Magnus,


I strongly advice you to download the manuals. It is an instrument that
is puzzling at times, so the manuals are needed. The upside is that they
are really interesting. The operators and programming manuals get you
understand what it really does. You also want the service manual.
Anyway, last time I looked I could download them from Agilent/Keysight.


I have downloaded what's there, unfortunately there's no operator's manual but I did the 
"Getting Started Guide" with the instrument. The prog manual might stimulate me 
to get GPIB up and running.


See the other link. The trick is to search for "5372A" and not for 
"HP5372A".



Trigger jitter. More importantly, now you see it!
The trigger jitter follows the formula:



t_jitter = e_n / S



e_n is the noise voltage RMS value
S is the slew-rate
t_jitter is the trigger jitter RMS value



That explains it nicely! As you would expect the jitter is much less when a 
square wave is the input.


Great!


I will look into the manuals to see the spec and what can be done about it. 
Measuring it as you suggest will be an interesting project.


Hint: Check the Numeric presentation and see the standard deviation, 
which will work as you collect blocks of samples, let's say 8000.



Maybe it's something that resulted from the long period of inactivity the 
device had. I will also check the power supplies for voltage accuracy and 
ripple.


Well, do the check.

Figure out how you can make the HP5372A to calculate the slew-rate for 
you. Voltage divided by time is the hint. :)
With that, you can measure slew-rate and jitter (standard deviation) of 
the different signals. You can then experiment with amplitude and frequency.


73 de SA0MAD Magnus
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Re: [time-nuts] HP 5372A advice

[Poul-Henning Kamp]

In message <569fde69.2020...@rubidium.dyndns.org>, Magnus Danielson writes:

>Good, then I have not remembered completely wrong.

The 5371 and 5373 manuals are not without relevance either, and
don't overlook the app-notes and the HPJ (1989-02) articles either.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] PRS10 C900 replacement

[Bob Camp]

Hi

Tantalums can benefit from a 1K resistor sort of “rebuild”. On any part made 
in the last 30 years by a major outfit, it should not be required. 

Moisture is sort of a weird issue. Epoxy and humidity do strange things. Getting
it back out is not easy. It also combines with the “guts” of the part. The 
failure 
mechanism is not the same as soldering a SMD part that has been out in 
the wet world longer than it should have been.

Bob

> On Jan 20, 2016, at 9:27 AM, Clint Jay  wrote:
> 
> Do tantalum then benefit from being 'reformed'  in a similar fashion to wet
> electrolytics?
> 
> Do they recover from moisture ingress by baking in a similar fashion to SMD
> chips that have been stored incorrectly?
> On 20 Jan 2016 14:10, "Bob Camp"  wrote:
> 
>> Hi
>> 
>> 
>> The only thing I would add to that is:
>> 
>> Get it from Mouser or Digi-Key. That way you have a pretty good chance of
>> it being one
>> that really came from the manufacturer you think it’s coming from. You
>> also are a lot
>> less likely to get one that has been on the shelf forever and ever.
>> 
>> One really strange thing about Tantalum’s: They *like* bias and
>> temperature. The
>> time you are most likely to see high leakage is when they have been power
>> off for
>> a long time. That’s another reason to want a new one …
>> 
>> Bob
>> 
>>> On Jan 20, 2016, at 1:59 AM, Charles Steinmetz 
>> wrote:
>>> 
>>> david wrote:
>>> 
 It's a 2.2uF cap, with a 0.125" lead spacing, and I'm looking for 125dC
>> temp rating. I wondered if there were other characteristics such as ESR/ESL
>> I need to keep in mind.
>>> 
>>> You're on the right track.  Get the highest temperature rating available
>> (which is probably 125C), buy only caps manufactured by one of the
>> known-good manufacturers, and select from a parts series the manufacturer
>> designates as "high reliability" (or equivalent).
>>> 
>>> If it is a solid tantalum, I like the Vishay 199D Series.  The AVX TAP
>> Series and the Kemet "T" Series ("UltraDip II") are also high quality.
>> (This list isn't exhaustive -- these are just the ones I've had occasion to
>> qualify.)
>>> 
>>> Best regards,
>>> 
>>> Charles
>>> 
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
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>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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Re: [time-nuts] HP 5372A advice

[bownes]

Has anyone published a summary of the differences between the '71 & '72?


> On Jan 20, 2016, at 15:11, Poul-Henning Kamp  wrote:
> 
> 
> In message <569fde69.2020...@rubidium.dyndns.org>, Magnus Danielson writes:
> 
>> Good, then I have not remembered completely wrong.
> 
> The 5371 and 5373 manuals are not without relevance either, and
> don't overlook the app-notes and the HPJ (1989-02) articles either.
> 
> -- 
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Generating a solid PPS from 10Mhz source

[Bob Camp]

Hi


> On Jan 20, 2016, at 6:28 AM, Attila Kinali  wrote:
> 
> On Mon, 18 Jan 2016 14:34:56 -0500
> Bob Camp  wrote:
> 
>> The nice thing about a FPGA (or CPLD) is that they come with a cute timing 
>> analyzer. You can indeed
>> answer questions like this with a quite high level of confidence. That 
>> *assumes* that you bother to set
>> up the timing analyzer :) 
> 
> I wouldn't trust that timing analyzer too much. We just build a TDC using
> an Cyclone 4 FPGA here (actually, porting the OHWR delay line TDC from
> Spartan to Cyclone) and the timing analysis was... weird, at best.
> 

Been there / done that on both parts. The timing analyzer is doing what it is 
supposed to do =
analyze the worst case delays against the constraints you provided. It then 
makes sure that
the data gets where it needs to go “in time” for it to be correct. The approach 
is typical semiconductor
industry “six sigma over a billion cycles on a billion devices each with a 
billion gates” sort of thing. 
The result is a part that does indeed work. It’s not much use for predicting 
things like jitter.  

> Although the average delay was about right (40ps and 120ps) it only
> showed a two element structure, ie the delays of the chain were
> "40ps, 120ps, 40ps, 120ps,..." without any higher level structure
> (which should have shown). The test results showed a quite more
> detailed structure with few delays over 100ps and most being between
> 20ps and 80ps.

Some of which are fabric (routing) delays). Some of which are simply the analog 
nature of digital 
circuits (noise matters, gain matters). Some of them may be a result of auto 
routing the design rather
than manually placing everything. (Yes manual routing can help. It’s a major 
pain for fairly little gain).

> Interestingly, some were close to 0ps, for which
> we have no explanation good explanation.

The explanation is fairly simple, you have a clock and a “data pulse” flying 
down the delay / carry chain. With 
an ASIC you could make sure they take a very linear route through the silicon. 
With a FPGA you can’t do that.
Both are routed through this and that. When you get down to the ps level, there 
is no guarantee which one
gets there first. Even if there was, the aperture time on the flip flops is 
sensitive to things like voltage and temperature.
What you see this time may not be what you see that time. There are a whole 
bunch of papers on  all of this.
Bottom line, not all indicated data patterns can be placed in a nice orderly 
plot ( = you don’t know which one
came first). About the only way to order them is to count the zeros. Not 
perfect, but about the best you can do.

Bob

> 
>   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] Generating a solid PPS from 10Mhz source

[Bob Stewart]

Hi Poul,

Your comment about on-chip PLLs got me to wondering about the dsPIC33FJ128MC804 
I'm using in my GPSDO.  So, I put it on the 5370A to see what's up.  Input to 
the gate port is the drive signal for an LED that I flash at 1PPS (controlled 
by an on-chip timer).  I delay that with a 10ft piece of RG-58 to drive the 
start gate.  The stop gate is driven by the OCXO output from the GPSDO.  
Internally, the chip's PLL is running at 160MHz  (10MHz OCXO / 2 * 32), which 
is divided down to 80MHz for FOSC and then by 2 again for FCY, if you know 
these dsPICs.

The ADEV at 1s is about 1.7E-10, declining at about a decade per decade.  I 
take this to represent the jitter of the PIC's onboard RC oscillator as driven 
by the OCXO.

Bob




On Wed, 1/20/16, Poul-Henning Kamp  wrote:

 Subject: Re: [time-nuts] Generating a solid PPS from 10Mhz source
 To: "Discussion of precise time and frequency measurement" 
, "Attila Kinali" 
 Date: Wednesday, January 20, 2016, 8:13 AM
 
 
 In message <20160120122824.39fb655285dd0e68c3884...@kinali.ch>,
 Attila Kinali w
 rites:
 
 >The test results showed a quite more
 >detailed structure with few delays over
 100ps and most being between
 >20ps and
 80ps. Interestingly, some were close to 0ps, for which
 >we have no explanation good explanation.
 
 Any on-chip PLL's with
 "spread-spectrum" to fudge EMI tests ?
 
 -- 
 Poul-Henning Kamp       | UNIX
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Re: [time-nuts] Generating a solid PPS from 10Mhz source

[Attila Kinali]

On Wed, 20 Jan 2016 14:13:11 +
"Poul-Henning Kamp"  wrote:

> >The test results showed a quite more
> >detailed structure with few delays over 100ps and most being between
> >20ps and 80ps. Interestingly, some were close to 0ps, for which
> >we have no explanation good explanation.
> 
> Any on-chip PLL's with "spread-spectrum" to fudge EMI tests ?

Nope, the cyclone4 PLLs do not support spread spectrum.
Also, the 0ps positions were stable (suggesting some FPGA
internal feature to be the cause), but they weren't evenly
spread over the delay chain.

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] Generating a solid PPS from 10Mhz source

[Poul-Henning Kamp]

In message <20160120122824.39fb655285dd0e68c3884...@kinali.ch>, Attila Kinali w
rites:

>The test results showed a quite more
>detailed structure with few delays over 100ps and most being between
>20ps and 80ps. Interestingly, some were close to 0ps, for which
>we have no explanation good explanation.

Any on-chip PLL's with "spread-spectrum" to fudge EMI tests ?

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] PRS10 C900 replacement

[Attila Kinali]

On Tue, 19 Jan 2016 20:44:15 -0600
"Graham / KE9H"  wrote:

> You will need to know the capacitance value.  Usually expressed in uF
> (micro Farad).
> Then some idea of the physical size, so the replacement will fit in the
> current space.

According to the schematics sheet I have (from didier's site), the value
is 2u2. Unfortunately, there is no mention of the actual type of the case
(beside being radial).
As it seems to be part of an 107kHz low pass filter, I would assume
that most tantal capacitors and probably all ceramic capacitors that
fullfill the 35V spec are ok. As this is a heated part of the whole
circuit, i'd go for an capacitor that is rated for 35V@100°C or higher.

Good candidates for capacitor manufacturers are Kemet and AVX
(higher quality than the cheaper manufacturers and still reasonably priced)

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] HP 5372A advice

[Gary Chatters]

On 01/20/2016 03:59 AM, Morris Odell wrote:

Thanks very much for your reply Magnus,


[...]


I have downloaded what's there, unfortunately there's no operator's manual but I did the 
"Getting Started Guide" with the instrument. The prog manual might stimulate me 
to get GPIB up and running.



The Keysight website has eight manuals for the HP5372A, including two 
versions of "5372A Frequency and Time Interval Analyzer Operating 
Manual".  Is this not what you need?


There are also a Service Manual and a Programming Manual and others.

[...]
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Re: [time-nuts] PRS10 C900 replacement

[Clint Jay]

Do tantalum then benefit from being 'reformed'  in a similar fashion to wet
electrolytics?

Do they recover from moisture ingress by baking in a similar fashion to SMD
chips that have been stored incorrectly?
On 20 Jan 2016 14:10, "Bob Camp"  wrote:

> Hi
>
>
> The only thing I would add to that is:
>
> Get it from Mouser or Digi-Key. That way you have a pretty good chance of
> it being one
> that really came from the manufacturer you think it’s coming from. You
> also are a lot
> less likely to get one that has been on the shelf forever and ever.
>
> One really strange thing about Tantalum’s: They *like* bias and
> temperature. The
> time you are most likely to see high leakage is when they have been power
> off for
> a long time. That’s another reason to want a new one …
>
> Bob
>
> > On Jan 20, 2016, at 1:59 AM, Charles Steinmetz 
> wrote:
> >
> > david wrote:
> >
> >> It's a 2.2uF cap, with a 0.125" lead spacing, and I'm looking for 125dC
> temp rating. I wondered if there were other characteristics such as ESR/ESL
> I need to keep in mind.
> >
> > You're on the right track.  Get the highest temperature rating available
> (which is probably 125C), buy only caps manufactured by one of the
> known-good manufacturers, and select from a parts series the manufacturer
> designates as "high reliability" (or equivalent).
> >
> > If it is a solid tantalum, I like the Vishay 199D Series.  The AVX TAP
> Series and the Kemet "T" Series ("UltraDip II") are also high quality.
> (This list isn't exhaustive -- these are just the ones I've had occasion to
> qualify.)
> >
> > Best regards,
> >
> > Charles
> >
> >
> > ___
> > 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] HP 5372A advice

[Magnus Danielson]

Morris and Gary,

On 01/20/2016 03:36 PM, Gary Chatters wrote:

On 01/20/2016 03:59 AM, Morris Odell wrote:

Thanks very much for your reply Magnus,


[...]


I have downloaded what's there, unfortunately there's no operator's
manual but I did the "Getting Started Guide" with the instrument. The
prog manual might stimulate me to get GPIB up and running.



The Keysight website has eight manuals for the HP5372A, including two
versions of "5372A Frequency and Time Interval Analyzer Operating
Manual".  Is this not what you need?

There are also a Service Manual and a Programming Manual and others.


Good, then I have not remembered completely wrong.

Link-time:
http://www.keysight.com/main/facet.jspx?=US=eng=5372A=g

Operating manual:
http://literature.cdn.keysight.com/litweb/pdf/05372-90035.pdf?id=726057

Service manual:
http://literature.cdn.keysight.com/litweb/pdf/05372-90016.pdf?id=734204

Cheers,
Magnus
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Re: [time-nuts] Pendulum clocks based on John Harrison's writing

[Tom Van Baak]

Hi Ron,

That's a nice article. For more information on Clock B see:

http://leapsecond.com/pend/clockb/

Under "technical links" you'll see a copy of my presentation at the Harrison 
conference last year in Greenwich, with all the charts, graphs, and ADEV plots 
a time nut could wish for...

/tvb

- Original Message - 
From: "Ron Bean" 
To: 
Sent: Tuesday, January 19, 2016 7:06 PM
Subject: [time-nuts] Pendulum clocks based on John Harrison's writing


http://www.theatlantic.com/technology/archive/2016/01/pendulum-clock-john-harrison/424614/

|The contemporary British clockmaker George Daniels has called the text 
|“rubbish”; Rupert Gould, the author of the biography Burgess 
|read, described it as “gibberish.”
|
|Burgess disagreed.


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Re: [time-nuts] Thinderbolt 10 Mhz output level?

[Hal Murray]

time-nuts@febo.com said:
> Has anyone actually measured the 10 Mhz level on their thunderbolt? More
> than +10 dbm? 

My scope says 5V p-p unterminated.  Half that into a 50 ohm terminator.

[My brain doesn't think in dB.  You will have to do the conversion.]


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Thinderbolt 10 Mhz output level?

[Orin Eman]

I have now:

+11.7 dBm on the 8568A spectrum analyzer with 2nd & third harmonics at -60
dBc.

So yes, mine is a dB or two above +10dBm.

Orin.

On Tue, Jan 19, 2016 at 6:29 PM, Chris Arnold via time-nuts <
time-nuts@febo.com> wrote:

> Has anyone actually measured the 10 Mhz level on their thunderbolt? More
> than +10 dbm?
>
> Thanks
> Chris
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Re: [time-nuts] Thunderbolt 10 Mhz output level?

[Charles Steinmetz]

Chris wrote:

Has anyone actually measured the 10 Mhz level on their thunderbolt? 
More than +10 dbm?


Yes.  In my experience, generally +12.4 to +13.3 dBm into a 50 ohm 
load (nominally 1vrms).


Best regards,

Charles


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Re: [time-nuts] PRS10 C900 replacement

[Charles Steinmetz]

david wrote:

It's a 2.2uF cap, with a 0.125" lead spacing, and I'm looking for 
125dC temp rating. I wondered if there were other characteristics 
such as ESR/ESL I need to keep in mind.


You're on the right track.  Get the highest temperature rating 
available (which is probably 125C), buy only caps manufactured by one 
of the known-good manufacturers, and select from a parts series the 
manufacturer designates as "high reliability" (or equivalent).


If it is a solid tantalum, I like the Vishay 199D Series.  The AVX 
TAP Series and the Kemet "T" Series ("UltraDip II") are also high 
quality.  (This list isn't exhaustive -- these are just the ones I've 
had occasion to qualify.)


Best regards,

Charles


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Re: [time-nuts] Thinderbolt 10 Mhz output level?

[Bob Camp]

Hi

If it’s below 10 dbm, it’s broken in some way. That’s often something simple 
like the output 
coupling components or a solder joint on the coax connector. 

Bob

> On Jan 19, 2016, at 9:29 PM, Chris Arnold via time-nuts  
> wrote:
> 
> Has anyone actually measured the 10 Mhz level on their thunderbolt? More than 
> +10 dbm?
> 
> Thanks
> Chris
> ___
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Re: [time-nuts] PRS10 C900 replacement

[Bob Camp]

Hi


The only thing I would add to that is:

Get it from Mouser or Digi-Key. That way you have a pretty good chance of it 
being one
that really came from the manufacturer you think it’s coming from. You also are 
a lot 
less likely to get one that has been on the shelf forever and ever. 

One really strange thing about Tantalum’s: They *like* bias and temperature. 
The 
time you are most likely to see high leakage is when they have been power off 
for 
a long time. That’s another reason to want a new one …

Bob

> On Jan 20, 2016, at 1:59 AM, Charles Steinmetz  wrote:
> 
> david wrote:
> 
>> It's a 2.2uF cap, with a 0.125" lead spacing, and I'm looking for 125dC temp 
>> rating. I wondered if there were other characteristics such as ESR/ESL I 
>> need to keep in mind.
> 
> You're on the right track.  Get the highest temperature rating available 
> (which is probably 125C), buy only caps manufactured by one of the known-good 
> manufacturers, and select from a parts series the manufacturer designates as 
> "high reliability" (or equivalent).
> 
> If it is a solid tantalum, I like the Vishay 199D Series.  The AVX TAP Series 
> and the Kemet "T" Series ("UltraDip II") are also high quality.  (This list 
> isn't exhaustive -- these are just the ones I've had occasion to qualify.)
> 
> Best regards,
> 
> Charles
> 
> 
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Re: [time-nuts] Generating a solid PPS from 10Mhz source

[Attila Kinali]

On Mon, 18 Jan 2016 14:34:56 -0500
Bob Camp  wrote:

> The nice thing about a FPGA (or CPLD) is that they come with a cute timing 
> analyzer. You can indeed
> answer questions like this with a quite high level of confidence. That 
> *assumes* that you bother to set
> up the timing analyzer :) 

I wouldn't trust that timing analyzer too much. We just build a TDC using
an Cyclone 4 FPGA here (actually, porting the OHWR delay line TDC from
Spartan to Cyclone) and the timing analysis was... weird, at best.

Although the average delay was about right (40ps and 120ps) it only
showed a two element structure, ie the delays of the chain were
"40ps, 120ps, 40ps, 120ps,..." without any higher level structure
(which should have shown). The test results showed a quite more
detailed structure with few delays over 100ps and most being between
20ps and 80ps. Interestingly, some were close to 0ps, for which
we have no explanation good explanation.

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] HP 5372A advice

[Morris Odell]

Thanks very much for your reply Magnus,

> I strongly advice you to download the manuals. It is an instrument that 
> is puzzling at times, so the manuals are needed. The upside is that they 
> are really interesting. The operators and programming manuals get you 
> understand what it really does. You also want the service manual.
> Anyway, last time I looked I could download them from Agilent/Keysight.

I have downloaded what's there, unfortunately there's no operator's manual but 
I did the "Getting Started Guide" with the instrument. The prog manual might 
stimulate me to get GPIB up and running.

> Trigger jitter. More importantly, now you see it!
> The trigger jitter follows the formula:

> t_jitter = e_n / S

> e_n is the noise voltage RMS value
> S is the slew-rate
> t_jitter is the trigger jitter RMS value


That explains it nicely! As you would expect the jitter is much less when a 
square wave is the input. I will look into the manuals to see the spec and what 
can be done about it. Measuring it as you suggest will be an interesting 
project. Maybe it's something that resulted from the long period of inactivity 
the device had. I will also check the power supplies for voltage accuracy and 
ripple. 

Thanks again,

Morris VK3DOC
Melbourne, Australia

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