RTLSDR IQ imbalance ???

a c f6gnj78 at gmail.com
Mon Feb 27 13:30:57 UTC 2017

I use RTL-FM on a raspberry pi3. I notice practically always the
presence of a weak carrier accompanying the emission received in AM
mode and interferences in NFM mode. When i use rtl-tcp and sdr# or
sdrconsole the demodulation is perfect. I assume that IQ amplitude
phase correction is involved. I saw in the source of rtlsdr:
IQ estimation / compensation (en_iq_comp, en_iq_est) * /
Rtlsdr_demod_write_reg (dev, 1, 0xb1, 0x1b, 1);
I suppose we use an internal chipset function? Is this function good
enough? I did not find anything about it in RTL-FM but I'm not a
specialist. Is an improvement possible?

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