Hi,
If you have a mirror copy of the spectrum above the LO this always is caused by a big unbalance of the IQ signals. The imbalance can be caused by:
- The RX is not generating either I or Q signal. You can check this using a strong CW signal and a dual channel oscilloscope to see that the amplitudes are the same and the phase is in quadrature.
- The audio cable has one of the channels missing or have a short between them so I and Q are the same.
- The audio input is not stereo. This happens in most laptops.
-The audio input card or USB audio device has a problem. There was a ADC chip that sampled the channels alternatively so the samples were displaced in time. Most SDR software does not correct this. There was one that did it, but I don't remember which one.
Since the current audio input device could be the culprit, try with another audio system, for example an USB card. Beware that most audio input dongles are mono.
Regards,
Ignacio EB4APL
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El 28/01/2022 a las 23:53, al2ok escribió:
The RX is working again, it is back to OK. Except for the odd things I been trying to correct.
I still have the spectrum from LO frequency to left working correctly and what is on the right in spectrum of LO is a duplicate ( signal wise ) of what is on the left of LO, even though frequencies that display on RIGHT of LO in spectrum display are higher then left frequencies displayed in spectrum.
Somebody mentioned a short on the I & Q signals, if there was a short would it not work at all, if I & Q were shorted together? But I did check and there are no shorts.
As mentioned before it does these things on, Winrad & HDSDR . . . Rocky 3.8 works to but that has additional display issues, like I can't get all the frequencies the Rocky 3.8 setting claims to cover. Rocky 3.8 seems to be missing some frequencies.
But again - it works, sounds good and tuned frequency is the correct frequency on all 3 softwares.
Al
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