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Ghost program on WFM - RSPduo

Posted: Tue Mar 19, 2019 10:36 am
by Patrick73
Hi buddies,

I have an issue when tuned to 88.1 FM (+ some other frequencies) where I hear a station actually transmitting on 103.9 (their 0.1 kW TX is about 1km from home, -31dBm). Switching from LIF to ZIF, using decimation, adjusting manually the AGC does not help.
Lowering the RF Gain of course makes this harmonic disappear but I then I can not hear the "real" (weak) station on 88.1 because of lack of gain ...

No such problem using another well-known SDR.

How can I fix it ?
Thanks for the precious support.

Re: Ghost program on WFM - RSPduo

Posted: Tue Mar 19, 2019 11:59 am
by glovisol
In order to avoid front end overload, you should insert a 20 dB attenuator between antenna lead & RSP input. This is not necessary with other SDR because most probably they are less sensitive.

Re: Ghost program on WFM - RSPduo

Posted: Tue Mar 19, 2019 12:59 pm
by Patrick73
The other SDR is, at least, as sensitive. I suppose it better handles huge signals.
Unfortunately, I have no attenuator on hand to improve my duo performance, bad luck. I thought I was doing something wrong with its settings.

In any case, thanks for the advice. This is not a big issue, I can live with it ;-)