I've been working on a custom OFDM implementation and I'm getting a lot of packet_headerparser_b :info: Detected an invalid packet at item 23472 header_payload_demux :info: Parser returned #f errors.
It's not an issue at the start of the transmission but it certainly is after a while. It seems there's some kind of drift that increases throughout the transmission.
I think it's due to the FIR filter delay or something related to it.
Sync word 1: [0.0,1.536,0.0,-1.536]*int(fft_len/4); Sync word 2: [rd.choice(-1, 1) for i in range(128)]; Occupied carriers range from -22 to 22, excluding pilot carriers ((-19,-15, -5, 5, 15,19),) and 0. Everything else is visible in the picture given below:
I've tried using Rational Resamplers instead of the FIR filters, but didn't get much better results.
The value I noticed has the biggest impact is the rolloff lenght, which is currently set to 3.
EDIT:
I've also noticed quite a lot of high amplitude spikes occuring in the passband. After doing a little digging around, I've found out that these originate directly from the OFDM Transmitter. And the OFDM Receiver doesn't "receive" well when these spikes are lost (e.g. clipping when saving to WAV file).
