[600MRG] double reporting of strong wspr signals

[Dave]

Tests over the last few years show Its usually due to non linearities in the
soundcard. You will see the 120(and 100Hz) sideband reports fairly often on
the wsprnet.org reports on all the hf bands. It has been seen on decodes as
low as 0dB 

Even ground isolation transformers doesn't stop it

Experiment has shown that even running the transmitter off DC (eg lead acid
cell) you will still the "sideband" effects in the receiver, even when using
a better spec soundcard (eg d44 or the edirol). The worst experience was
with a $7 chinese USB soundcard where the main signal and the 2 "sidebands"
were equal amplitude, which gave the wspr decoding software a headache

Dave

Ww2r

 

-----Original Message-----
From: 600MRG [mailto:600mrg-bounces at w7ekb.com] On Behalf Of Hans Summers
Sent: Tuesday, March 04, 2014 10:12 PM
To: 600mrg at w7ekb.com
Subject: Re: [600MRG] double reporting of strong wspr signals

In my setup here I can often get 100Hz sidebands (50Hz mains power here, not
60Hz) produced in the receiver with very strong signals too. I'm not sure of
the mechanism.


73 Hans G0UPL, creator of the U3 :-)
Http://www.hanssummers.com