Envelope-to: dave@picks.force9.co.uk
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Date: Sun,  5 Feb 2006 00:20:58 +0100
From: uwe-jannsen@versanet.de
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: GPS locked tests
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Zitat von Dave Pick <dave@picks.force9.co.uk>:

> Dear all
>
> I have just received this from Peter Martinez G3PLX who is conducting tests
> with phase coherent GPS-locked signals on LF. He asked me to pass it on to
> the group so that you'll know what's going on!
>
> Dave G3YXM
> ---------------------------------
>
> For info, CT1DRP is now radiating a plain carrier on 136718.75Hz, locked to
> GPS. To give you an idea of what this means, if he triggered his scope from
> the GPS 1Hz pulse, set a timebase span of 10uS or so, and looked at his
> transmitter RF carrier waveform, it first shows a positive-going
> zero-crossing, then 1 sec later a negative peak, then one sec later a
> negative-going zero-crossing, and the a positive peak, and repeats that 4
> sec sequence with no drift.
>
> I am receiving in a similar fashion, and I am now able to measure the
> received signal phase in absolute terms. It's early days but we hope soon to
> be able to stay in phase over 24 hours. That means keeping the clocks with
> which we generate RF at each end in time with each other to within a few uS
> over a day. The signal itself, of course, drifts late in phase at night and
> advances in the morning, typically by 2-3 cycles.
>
> The significance of the frequency he is using is that it's a nice round
> number that I can lock to (I work in whole Hz and simple fractions of a Hz)
> and it's a nice round number that he can generate with his GPS-locked DDS
> (His DDS steps in multiples of 5000000/(2^32) and 136718.75 is 5MHz*7/256.
>
>
>

Hi Dave and Peter,
CT1DRP stopped the transmitting at 2252UTC, is that correct?
regards
Uwe/dj8wx