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Thanks Paul,There could be another reason, see attachment. So far the phase is inverted within SpecLab, not by e.g. keying a relay by the serial interface. Due to the PLL and time delay in the sound card chain this takes some time. With a short symbol length of 12 seconds the effect may become relevant. A phase turn of 180 deg is done by varying the frequency for a certain time as you can see. So maybe this costs a dB of SNR here?For a 7 second symbol length in the 75 character message i will need a different technique, taking 'no' time for the phase inversion. Another thing could be the moving sunrise / sunset time on our path. We already saw a wider phase variation in the 20 character message than in the 7 day 'TEST' message before. Maybe it is even worse now. Am 16.11.2016 19:48, schrieb Paul Nicholson: For 1uW ERP, DK7FC to Todmordenhttp://abelian.org/vlf/tmp/1479317903_9356.png That plot must have been valid 2 weeks ago. What does it show now? Maybe it is a good idea to start 08:15 UTC instead of 08:00 UTC... Could it (it = the move of the positive green slope towards later times) be the reason for the higher phase variations that we can see? 73, Stefan
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