back on the topic of carrier recovery... in O-QPSK the phase has a uniform distribution, so I guess it's unsurprising that a costas loop doesn't quite work. that or I'm doing something wrong, which is...
here's how it performs under 15dB of SNR, with the loop filter being a 64-tap blackman window followed by an integrator (because the Alba doesn't know shit about control theory, let alone PLLs)
the two vertical lines indicate the start of the burst and the end of the preamble (or what would be the preamble -- this simulation has random O-QPSK symbols) and the vertical line is the true carrier frequency (100kHz here)
the two vertical lines indicate the start of the burst and the end of the preamble (or what would be the preamble -- this simulation has random O-QPSK symbols) and the vertical line is the true carrier frequency (100kHz here)
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