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

[Bob Camp]

Hi

Unless you have a very fancy receiver, the cabling should not matter much. The antenna is a bigger issue, but again it depends on just how fancy you are getting and how good the antenna is. Right now, I would not worry about either one. Use good quality RG-6 quad shield satellite TV coax and it should be fine.

Location of the antenna matters more than either of the above. You want a good view of the southern sky. 

Bob

On Dec 15, 2012, at 9:02 AM, Fabio Eboli <fabioeb at quipo.it> wrote:

> 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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