sjg
5205c067fc
Replace bandpass filter envelope detector with delay-and-multiply frequency discriminator. Add biquad bandpass pre-filter centered at 1700 Hz to remove out-of-band noise. Replace IIR low-pass with moving-average LPF over half a bit period, which places a null at 2x mark frequency for clean discriminator artifact removal. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>