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bastibl / gr-ieee802-15-4

IEEE 802.15.4 ZigBee Transceiver
https://www.wime-project.net
GNU General Public License v3.0
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extract some RF fingerprint features #79

Open Chen-Sanyuan opened 1 month ago

Chen-Sanyuan commented 1 month ago

I want to extract some RF fingerprint features based on the physical layer of gr-ieee802-15-4. These RF fingerprint features are CFO, IQ imbalance, PA nonlinearity, antenna pattern. How should I achieve this goal? Thanks

bastibl commented 1 month ago

IQ imbalance, PA nonlinearity, and antenna pattern are independent of this module. The CFO is corrected with the IIR filter, following the demodulator.

Chen-Sanyuan commented 1 month ago

Does this mean that I can estimate CFO by calculating the phase difference after processing it through the IIR filter? Thanks

bastibl commented 1 month ago

You can regard O-QPSK as a form of FM and decode it accordingly. If you were perfectly synchronized the average phase difference between consecutive samples (that's what the quadrature demodulator outputs) would be zero. If you introduce a CFO, it shifts the output of the demodulator away from zero. The bigger the CFO, the bigger the shift. The IIR filter calculates the average and later subtracts it, to compensate the CFO and get back to a signal with a zero average.

Chen-Sanyuan commented 1 month ago

So, the result of the IIR filter is the CFO? Thanks a lot.

bastibl commented 1 month ago

Yes, it's the estimate of the CFO in radians per sample.