locked Re: poor transmissions #wsjt-x


Jim Brown
 

On 7/3/2021 5:29 AM, KD7YZ Bob wrote:
To repeat, are my settings causing the program to NOT decode some stations which may be underneath all the 'ringing' ?
Overload anywhere the signal is audio will generate harmonics and intermod. This can happen between the detector in your radio and the WSJT-X decoder, and between the other station's WSJT-X and his SSB modulator. If you're seeing it mostly the strongest signals, it's on your end; if on signals that are not the strongest, it's them.

The setting of the output level from the radio can be too high, the input gain of the computer can be too low or too high. On the TX side, the output level of the computer can be too high, and the input gain of the rig can be too high or too low.

I mostly use WSJT-X on 6M and 160M, and I rarely see dirty signals. I recently did help a neighbor clean up his signal; he was using an SPE 1K amp to run about 300W, and had the amp set for Low Voltage. His sidebands were full of noise, and only about 35 dB down. He switched to high voltage, and sidebands dropped by about 6 dB.

A few hours later, I looked at another neighbor, N5KO, running a IC7300 and KPA1500; his sidebands were 50 dB down, and clearly defined the same width as the signal and spaced 300 Hz from it; second set were about 6 dB below that.

73, Jim K9YC

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