3 ms·

I wonder what data rate is actually possible on a cassette tape, using modern modulation and error correction techniques? A blog commenter claimed to get 13.8

by p1mrx 6y ago

I wonder what data rate is actually possible on a cassette tape, using modern modulation and error correction techniques? A blog commenter claimed to get 13.8 kbps per channel using Digital Radio Mondiale with OFDM+QAM, but I didn't see an obvious way to reproduce this: http://www.windytan.com/2012/08/vintage-bits-on-cassettes.html http://www.windytan.com/2012/08/vintage-bits-on-cassettes.ht... There are various data modes for ham radio (e.g. JT65), but tapes are better in some ways (bandwidth) and worse in others (wow and flutter), so those codecs seem ill-suited.

jrockway 6y ago
I am not sure of the magnitude of wow and flutter on tapes, but the amateur modes definitely account for some frequency shift -- for HF, the ionosphere can shift the frequency randomly (I kind of thought I was making this up, but found some papers on it: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009RS004210 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200...), and radio local oscillators are not perfect (usually temperature dependent). (For other modes like airplane scatter, meteor scatter, EME, satellite, etc. there is even more doppler shift.)