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I have a problem with recording SWS-morse using SDRSharp and RTL-SDR. I want fixed gain, not audio automatic gain control. The problem is that all signal but the weakest will cause the recorded audio to be saturated with disastrous result.

When recording FM audio there is no problem How do I adjust the recording level manually in SDRSharp?

I have tried a recording addon: same bad result.

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  • $\begingroup$ Make sure that the AGC in the RTL2832U is turned off (rtl_tcp command 0x08, parameter = 0). It's AGC set-point is much to high for anything except maybe for DTV. Then lower the manual RF gain of the R820T2 (rtl_tcp commands 0x03 & 0x04). $\endgroup$
    – hotpaw2
    Mar 24, 2019 at 16:09
  • $\begingroup$ Ok thanks for responce. What I don't understand is how to use this rtl_tcp command when I am using rtl-usb. Do I have to switch using rtl_tcp, or what ?? ( jfyi: I am new in this world of SDR ) $\endgroup$
    – enocknitti
    Mar 25, 2019 at 6:49

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You're pretty clearly experiencing numerical wraparound: the two numbers produced by the ADC combine to a complex number $z=I+jQ$ with $|z|>1$, and thus, numerically, you suddenly get a switchover.

Reduce the gain by 3 dB. This should give you enough headroom.

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    $\begingroup$ Yes is numerical wraparound, My problem is that I can't find out how I reduce gain. Btw I am using direct sampling for SW ( not SWS ). I might also add that in most cases the overflow is much worse. I need at least -10 db $\endgroup$
    – enocknitti
    Mar 23, 2019 at 19:19

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