[time-nuts] PicTic Data

[Bruce Griffiths]

Bruce Griffiths wrote:
> An ACAM GP2 evaluation board is available here:
> http://shop.omegacs.net/
>
Ignore this link as I omitted to read the fine print!!!!

> However an ACAM GP1 would probably be a better fit in a DMTD with a 
> beat frequency of 10Hz or more as the GP1 has a measurement range of 
> 200ms.
>
> Bruce
>
> Stanley Reynolds wrote:
>> Thanks for looking at my data that was what I was fishing for all 
>> along :-)
>>
>> I was looking at the article:
>>
>> "A Small Dual Mixer Time Difference (DMTD) Clock Measuring System 
>> W.J. Riley "
>> Richard posted
>>   And thinking it would be nice to do the DSS and Mixer boards to go 
>> with the
>> pictic II.
>>   Or changing the Pictic II to use the Acam TDC GP2 Time to Digital 
>> Converter; 2
>> channel w/65 ps resolution now under $30. as Bruce suggested a while 
>> back.
>>   My wants sure exceed my cans ;-)
>>   Stanley
>>
>>
>> ----- Original Message ----
>> From: John Miles<jmiles at pop.net>
>> To: Discussion of precise time and frequency 
>> measurement<time-nuts at febo.com>
>> Sent: Sat, August 14, 2010 11:25:44 PM
>> Subject: Re: [time-nuts] PicTic Data
>>
>>
>>> John glad you are getting good results and have something to
>>> compare to. Back to
>>> me who doesn't have any knowns but lots of guessing. Attached is
>>> a run with a
>>> box cover over the pictic, run is shorter ~ 800 seconds but the
>>> box does look
>>> like it helps.
>>> I need to do a lot more testing but sometimes I just get excited :-)
>> I imported your .txt file alongside the traces I captured.  Assuming 
>> it was
>> taken with 1 Hz on both START and STOP, it looks like the attached.
>>
>> You're getting the exact sort of results that I see if I feed both 
>> the START
>> and STOP inputs at 1 Hz.  My guess is that the onboard oscillator 
>> limits the
>> performance in that case, since it has a lot of time to drift during the
>> measurement if the two pulses occur close to 1 second apart.  Even 
>> the 5370B
>> looks much worse if driven with 1 Hz on both inputs than it does with 
>> 1 Hz
>> at START and 10 MHz at STOP.
>>
>> So I think you're basically up and running OK.  When I get around to 
>> trying
>> a better clock, I'll also go back and see if the 1-pps x2 performance
>> improves.
>>
>> It would be great if the next spin of the board could include 
>> sine-to-CMOS
>> shapers for the input channels as well as an external clock input, for
>> people who are working directly with RF signals as opposed to 1-pps.
>>
>> -- john, KE5FX
>>
>>
>>> ----- Original Message ----
>>> From: John Miles<jmiles at pop.net>
>>> To: Discussion of precise time and frequency measurement
>>> <time-nuts at febo.com>
>>> Sent: Sat, August 14, 2010 10:19:46 PM
>>> Subject: Re: [time-nuts] PicTic Data
>>>
>>> A few preliminary measurements here (I'm working on getting some 
>>> software
>>> support together):
>>> http://www.ke5fx.com/pictic.htm
>>>
>>> -- john, KE5FX
>>>
>>>> -----Original Message-----
>>>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
>>>> Behalf Of Stanley Reynolds
>>>> Sent: Saturday, August 14, 2010 7:12 PM
>>>> To: Discussion of precise time and frequency measurement
>>>> Subject: Re: [time-nuts] PicTic Data
>>>>
>>>>
>>>>
>>>>
>>>> My guess as to what the data may indicate is performance of the
>>>> 10 Mhz 20PPM
>>>> PICTIC internal oscillator, need to repeat test with precision
>>>> 10Mhz and auto
>>>> calibrate off. Fatness of the line/width maybe PICTIC error. Note
>>>> graph seems to
>>>> show me leaving the room and returning via the outside door. Not
>>>> sure what the
>>>> ~100 sec oscillations are, need to check a/c cycle time.
>>>>
>>>> Stanley
>>>>
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>>>
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>
>
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