[Lowfer] WSPR for Dec.14-15

John Andrews w1tag at charter.net
Sat Dec 15 16:24:55 EST 2012


All,

I have frequently had a problem here with WSPR on 2200M with the strong 
60 Hz related lines at this QTH. This results in multiple signals and 
false decodes. Thus far there is no cure, as the sources are at 
neighbors' houses. I would suggest not running a noise blanker in your 
receiver, though.

Note that I have generally not had this issue at 600M, which is quieter 
here, 60 Hz-wise. But there I have to live with PDM crud from a nearby 
broadcast transmitter. Guess you can't have everything...

John, W1TAG

On 12/15/2012 4:16 PM, Eric NO3M wrote:
> John
>
> It seems like there might be sidebands getting produced with strong
> signals in your RX chain somewhere.  WE2XGR/2 triggered a few also:
>
> 2012-12-15 06:16      WE2XGR/2      0.475622      +3      0
> FN31ls      20 VE3EAR
> 2012-12-15 06:16      WE2XGR/2      0.475687      -27      0
> FN31ls      20 VE3EAR
>
> additional double decodes at 09:54, 10:14.  I think our proximity and
> higher signal level made the situation more pronounced, up to 4 sideband
> decodes per session in addition to the primary signal.
>
> I doubt it's something in the TS-440 unless there is a mixing problem
> that's creating close-in sidebands.  You might try adjusting audio
> levels between TS440 -> DSP and DSP -> Soundcard, while maintaining a
> non-signal noise level of 0dB (+/- a few dB) in the WSPR software (set
> with radio on a clear freq.).  If you are using WSPR 2.21, you might
> have to knock the audio down even further than with WSPR 2.11.  I've
> noticed the newer version reports much higher noise levels at the same
> audio settings when adjusted correctly for the old version.
>
> If you are using a pre-amp ahead of the TS440, that may be another
> potential contributor when exposed to strong in-band signals.
>
> 73 - Eric NO3M, WG2XJM
>
>
> On 12/15/12 15:41, John Bruce McCreath wrote:
>> Hi Eric, Lowfers,
>>
>> I could very well have a problem here.  From the beginning, my WSPR
>> decodes have been prone to displaying "false stations".
>> This happens on both 600 M and 2200 M, where the only difference in
>> the setup is the antenna.  The balance of the chain is
>> my TS-440, a Timewave DSP filter, an audio isolation transformer and
>> the SoundBlaster audio card in the older Pentium II.
>> The settings on the DSP filter are to create a passband from 1300 to
>> 1700 Hz.  Maybe I should make the window wider?
>>
>> I have logged trans Atlantic decodes from several European and UK
>> stations, so the setup certainly does work for me, but I'd
>> be really pleased if I could resolve the false decodes problem.
>> Because of them, I've been reluctant to upload the spots to
>> the WSPR web site unless I'm here in the shack to keep an eye on it.
>> I'm open to any suggestions you may have.
>>
>> 73, J.B., VE3EAR
>>
>> LowFER Beacon "EAR"
>> 188.830 kHz. QRSS30
>> EN93dr
>>
>>
>>
>>
>>
>
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