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Why does USB have so much less audio output than LSB? I've checked all settings and they are correctly set or not used, like AGC etc. Using same band pass on both modes.

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  • $\begingroup$ It would help if you explained how you came to this conclusion. $\endgroup$ – Phil Frost - W8II Feb 25 '18 at 3:29
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Not knowing your level of experience with the various amateur radio modes, be aware that for a given SSB (single side band) signal, only one of the side bands (upper or lower) is transmitted. The carrier and the other side band are significantly suppressed in the transmitted signal.

Since USB (upper side band) tends to be used on the higher frequency bands, you may simply be experiencing the difference in gain of your DSP or your antenna system on these higher frequencies. Normally, a properly configured AGC block will minimize this variation but it cannot completely eliminate it.

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  • $\begingroup$ Thanks for the responses. No. I'm quite experienced in receiver design being an applications engineer type and many decades as a ham. SDR is my first exposure to the A/D type approach though. The difference in level of audio out between LSB and USB has me wondering why. It has to be something about filtering or slope of response. I will keep at it to figure it out. $\endgroup$ – Jim Feb 25 '18 at 18:51
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Figured out the audio level difference between USB and LSB. With USB the AGC selection became active then using LSB it turned off. Settings are not permanent but need checking for each frequency selected! 73, Jim K5BTV

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