[time-nuts] MT3339 PA6H and Racal Dana GPIB, update

Fabio Eboli fabioeb at quipo.it
Sat Dec 15 14:02:56 UTC 2012


Thank you all for the advices.
I will prepare the setup for a longer logging session,
using an inverter and a battery for power backup.

Now I'm starting building of a clock shaper
and a divider for the 10MHz signal, I will use
7AC gates for both the squarer and divider, since I
have many of them here, no need to buy anything.

The question is: watching the previous log,
how much will the results be influenced by
the GPS antenna and it's cabling ?
(now I'm using this one:  
http://www.mirifica.it/store/gps-antenne/347-globaltop-fgpane-sma-5-m.html)

Thanks,
Fabio.

Azelio Boriani <azelio.boriani at screen.it> ha scritto:

> Yes, this is the typical GPS receiver PPS wander. It is usable for a GPSDO
> as it seems of timing quality (the Motorola M12M is -20nS..+20nS over 10
> days).
> See:
>
> http://www.jackson-labs.com/assets/uploads/main/Motorola_M12.pdf
>
> on page 7.
>
> On Thu, Dec 13, 2012 at 2:47 PM, Bob Camp <lists at rtty.us> wrote:
>
>> Hi
>>
>> Ok, those plots look much more "real". Thanks for sharing.
>>
>> Bob
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Fabio Eboli
>> Sent: Thursday, December 13, 2012 7:58 AM
>> To: time-nuts at febo.com
>> Subject: Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update
>>
>> Bob, timenutters
>> here are the first results, hope
>> I'm not boring the members with these
>> posts, for most participants these
>> are basic things.
>> Now I'm trying to understand if the
>> setup is working or I have to modify
>> some things.
>>
>> The logging is at 47000 samples and going,
>> the script is working well now, and I dont
>> have glitches so far.
>> Raw data, time interval between the pulses:
>> http://www.flickr.com/photos/14336723@N08/8269800802/
>>
>> Positive thing is that the drift seem consistent
>> with the previous decimated pulse period data.
>>
>> Data corrected for linear drift and offset, the
>> actual values are in the graph:
>> http://www.flickr.com/photos/14336723@N08/8269800868/
>>
>> Here I dont' like very much what I see,
>> but surely I'm not knowledgeable enough
>> to judge the data :)
>>
>> Some notes for who didnt read previous posts:
>> Racal 1992 counter, start on pps from FE5680 #1
>> stop on gps pps from PA6H GPS module,
>> Counter External standard is 10MHz from FE5680 #2.
>>
>> The Fe5680 #2 was powered one hour before the
>> session start, and it's mounted near the FE5680 #1,
>> so there is some thermal stabilization
>> in the first hours.
>> Also I dont have any signal amplification and
>> squaring, the trigger on the counter is set
>> at half the pulse peak voltage, both rising
>> edges.
>>
>> Is the graph what I should expect from the gps
>> signal, or I'm seeing some problems in the
>> setup?
>>
>> Thanks,
>> Fabio.
>>
>> Bob Camp <lists at rtty.us> ha scritto:
>>
>> > Hi
>> >
>> > That approach works well. If you have them about a half second apart
>> > I'd stick with that setup.
>> >
>> > Bob
>> >
>>
>>
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>>
>>
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