Re: LF: Re: 137khz RX-Test

["James Moritz" <james.moritz@btopenworld.com>]

Dear Markus, LF Group,

Thanks for the screen shot from Sunday night

> The appended clip shows four of your sequence repetitions, as seen in a 
> high resolution 21 mHz FFT - of course not readable but
> still showing consecutive dashes as a line in the upper trace and a gap in 
> the lower one. The emission appears to be phase coherent
> across symbols of the same type, but not across frequency switching. 
> Apparently the shift does not happen to be an exact integer
> multiple of the symbol rate, and after returning to the original frequency 
> the phase has lapsed by some amount.
The DFCW was generated, via sound-card output and transverter, by DL4YHF's 
Spectrum Lab "Digimode Terminal", set to 0.2 symbols/s and 2Hz shift. I 
think that would make some of the inter-symbol spaces 2.5s, so not an exact 
multiple of 0.2s maybe? I guess Wolf could confirm exactly how the phase is 
determined...
Cheers, Jim Moritz
73 de M0BMU