3 ms·
I used my 16-bit 192 kHz sound card to determine how much data can fit on a cassette by "prolonging" the length of each bit until I got an acceptable error rate
by sprash 5y ago
I used my 16-bit 192 kHz sound card to determine how much data can fit on a cassette by "prolonging" the length of each bit until I got an acceptable error rate. I found that the absolute best you can do with a decent old Technics tape deck is 8-bit at 12kHz which means for a 90-min Tape you can fit about 60 MB on one tape.
I noticed however that switching between bits produced a "ringing artifact" oscillating at about 60 kHz. If this is caused by my particular setup I don't know. With a better modulation than just PCM this could be compensated and you could pull probably more data out of the stream.
- klodolph 5y agoThat 60 kHz tone could be the tape bias frequency. https://en.m.wikipedia.org/wiki/Tape_bias https://en.m.wikipedia.org/wiki/Tape_bias
- sprash 5y agoThanks for the hint. The next thing to try would be to connect the tape head directly to the IO-Pins of a Raspberry PI and then use a simple manchester encoded signal ramping up the frequency. A Raspberry PI can push up to 1 MHz and has an internal Schmitt-Trigger which would be perfect for reading the data back.
- klodolph 5y agoYou’re going to have to deal with the nonlinearity of tape yourself, if you go this route.
- cmrdporcupine 5y agoHoly crap that's way more data than I could ever have imagined being possible on regular cassette.
- deleted 5y ago[deleted]