Dear Mauro, Stefan,
this duplicate signal has been noticed in the past at +/- 50Hz, due to mains
frequency humm (or ripple) at either TX or RX side. But 27Hz is a bit odd.
As Stefans suggested moving the TX signal some Hz and observing the ghost
signal might give a clue if higher order IM is involved.
In addition one could also look 27Hz up from the signal where - in case off
some kind off humm/ripple - the other sideband should appear.
73, Rik ON7YD - OR7T
________________________________________
Van: [email protected] [[email protected]]
namens Stefan Schäfer [[email protected]]
Verzonden: dinsdag 20 november 2012 23:26
To: [email protected]
Onderwerp: Re: LF: strange "duplication" of DK7FC WSPR spots
Hi Mauro,
Oh, good question. A difference of 27 Hz, odd. I have no idea. Other
stations, including me, must observe the same.
We could do the following test: I move my QRG by 5 Hz and then we will
see if the offset is still the same or if it becomes 10 Hz more or less...
73, Stefan
Am 20.11.2012 22:58, schrieb IK1WVQ Mauro:
> Hi to all,
>
> I see this strange behaviour of the DK7FC WSPR spots:
>
> 2136 -24 6.5 0.475614 0 DK7FC JN49 30
> 2136 1 6.5 0.475641 0 DK7FC JN49 30
> 2142 -27 6.5 0.475614 0 DK7FC JN49 30
> 2142 0 6.5 0.475641 0 DK7FC JN49 30
> 2148 -28 6.5 0.475614 0 DK7FC JN49 30
> 2148 -2 6.5 0.475641 0 DK7FC JN49 30
>
>
> At each time slot I receive 2 spots, one strong (0 dB), and the other
> weak (-27dB) ..
>
> Is this an artifact of my receiver (RACALL 1792, ant. PA0RDT) ???
>
> 73 de Mauro IK1WVQ
>
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