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Message-ID: <7D653C9C42F5D411A27C00508BF8803D06F5D180@mail.dstl.gov.uk>
From: Talbot Andrew <ACTALBOT@mail.dstl.gov.uk>
To: rsgb_lf_group@blacksheep.org
Date: Mon, 16 Oct 2006 08:44:19 +0100
MIME-Version: 1.0
Subject: RE: LF: GPS Locked test transmission
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Status: O

OK, I'll switch it off this evening. I noticed at one point on Saturday,
around mid-day, the GPS Rx briefly lost lock for a few seconds - presumbaly
because the antenna view of the sky is blocked in one direction and the
satellites were in an unfavourable set of positions at that time.  When lock
is lost, the 10MHz reference from the el-cheapo commercial GPSDO I am using
wanders in frequency by several ppm while the GPS is searching for the
signal.  It then takes a couple of minutes to re-stabilise once GPS lock is
reacquired.   In that case the phase of the transmitted signal will
permanently shift, giving a jump in any long term phase monitoring.  

I am transmitting the test signal from a dedicated set of equipment in a
shed in the garden - the 'trials cabin'.   Perhaps in future the reference
siugnal should be fed down to the shed from the shack where a better quality
reference signal can be guaranteed.

Andy  G4JNT


-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of
uwe-jannsen@versanet.de
Sent: 15 October 2006 22:14
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: GPS Locked test transmission

Zitat von uwe-jannsen@versanet.de:

> Zitat von Andy Talbot <andy.g4jnt@googlemail.com>:
>
>> I am using th3 AD9852 DDS for this transmission with its 48 bit 
>> tuning word, so frequency setting is to within 10^-14 - in other 
>> words exact ;-)
>>
>> I have only just subscribed to the reflector on my home email account, so
>> would otherwise have missed  this thread.   I was hoping to go to bed
early
>> tonight for a early start walking tomorrow, so will do a shorter off 
>> period than Uwe suggested.  I'll drop power at 2100z , go off at 
>> 2130z then on again at 2200z
>>
>> Andy  G4JNT
>>
>>

Hi Andy,
sri, received nothing on 137000.000Hz last night.
comming weeks I have to lead some committees, so the Clicklock experiments
cant go on.

pse see

http://home.versanet.de/~uwe-jannsen/Clicklock1.htm

last two pics.

regards
Uwe/dj8wx




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