Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz

[DK7FC <selberdenken@posteo.de>]

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 Todmorden
>
>  http://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

PSK_Regelzeit.png
Description: PNG image