IQ amplitude phase correction #3
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Improve tuner precision by calculating the VCO divisor at full precision, not at kHz resolution. Also replace the manual divison loop with a simpler fixed-point calculation.
This scans 0 - 3GHz looking for frequencies that can be tuned to without error, and refines the band edges further once a tuneable band is found. It should work with any tuner that correctly reports tuning errors. It takes about 1.5 minutes to complete on a R820T.
This fixes out-of-range frequencies that would set the PLL registers to incorrect values rather than failing outright.
Remove unused variables. Use proper type specifier. Explicitly cast to correct type to suppress MSVC warnings.
- Link librtlsdr dynamically also on Windows.
From Bjørn Forsman
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Hi, is this MR still relevant? I have adopted latest changes from https://github.com/librtlsdr/librtlsdr, so mey-be it will be more appropriate to open MR into that repo, althought it is not visibly upstream here. |
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Hello,
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?
Regards,
Arnaud