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IFGR range - why 20 - 59 not 0 - 59?

Posted: Tue Oct 10, 2017 2:08 pm
by mike_haben
Please can someone tell me why the minimum value for IFGR allowed by SoapySDRPlay is 20 rather than 0?

Thank you,
Mike H.

Re: IFGR range - why 20 - 59 not 0 - 59?

Posted: Tue Oct 10, 2017 3:44 pm
by mike_haben
After digging through some docs and code, answered the question for myself - in the "SDR API specification" document, section 3.37 on function mir_sdr_RSP_SetGrLimits() answers it indirectly:
<QUOTE>
This function provides a mechanism to extend the normally useful IF gain reduction range to include values less than 20dB when using mir_sdr_RSP_SetGr(). It is not recommended to use the extended range as it is likely to overload to produce signal levels that will overload the ADC input.
</QUOTE>

Hope this might save time for others in the future...