LF: Anoterh WSPR timing error

[Andy Talbot <andy.g4jnt@googlemail.com>]

John, G0API, has been monitoring my QRP WSPR beacon most of the afternoon, and getting the occasional decode at a S/N of -19dB, ie quite good.

However, he only manages a decode about one time in 10, randomly.  The frequency is usually reported as ....855 instead of the ...870 it should be, although once in a while, it reports 870 and gives a proper decode.   So it looks as if he may have some sort of intermitetnt fault that affects sampling rate.

 

After thinking about the problem with G0NBD's signal recently, I tried breaking my transmission, sending just the first 30 seconds, the first minute etc and seem to have hit on some success. 

 

In both cases, where I sent the first 45 seonds and 1 minute, it  decoded correctly at his end, albeit still a reported frequency of ...855.   So, I'm assuming John has as soundcard sampling rate error, and have now sent him away to inject an accurate 1500Hz tone as see what the WSPR software's own spectum display reports it as.   If the sampling rate is as far away as the 870/855Hz errors suggest, it sould be around 1% out.

 

Curiouser and curiouser...

 

I see signal strength at M0BMU has hardly altered as we've gone from day to night.   No D-Layer artefacts over a 120km path ?

Andy  G4JNT
www.g4jnt.com