New answers tagged gnuradio
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Map 0 to 1 and 1 to -1 on both the reference sequence and the received bit sequence, and then correlate; an inversion will also just invert the sign.
If that mapping is hard to do on the received signal, because it's not yet decided, just use an appropriate high-pass filter: that would convert your (noisy) monopolar sighal to a bipolar one, centered around ...
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Ive seen online sdrs have a mixer that downconvert the frequency band to baseband and then its sampled
I think your question can be answered by clearing up the misunderstanding that made you write this part of your question.
All data captured by an SDR is translated down from its original frequency down to being centred around a frequency of 0 Hertz (...
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To align the samples (and realigning with different filter implementations) consider implementing actual timing and carrier recovery loops, or using those discriminators and approaches to manually correcting the offsets as would be done in those acquisition and tracking loops. This will put you on the road toward an actual implementation when the transmitter ...
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I'm not familiar with what Gnu radio offers, but in pure signal processing terms, you're way overthinking this.
You just need a plain old PLL, with a plain old phase detector that multiplies the incoming signal with the NCO output, a plain old loop filter, and a plain old NCO with a sine wave output.
This is the sort of PLL you'd use in a synchronous AM ...
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The script below is my solution for my case. I hope that it could be useful for anyone facing the same issue. The code can be directly pasted in a "Embedded Python Block". I wrote some comments to explain the mechanism. I hope you find well. Any kind of improvement is welcome!
import numpy as np
from gnuradio import gr
import pmt
class ...
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