Reply to post: Well the requirements of loading data overlap with the requirements for audio

Analogue tones of a ZX Spectrum Load set to ride again via podcast project

Christian Berger

Well the requirements of loading data overlap with the requirements for audio

Essentially audio tape formats in the home computer era work by storing pulses on the tape. This was done in order to keep the hardware simple and to be able to deal with extremely horrible tape decks running at the wrong speed.

If you manage to keep a pulse vaguely coherent, you will be able to get the data through. This is also called a linear phase response, or a constant group delay. This isn't as important for general audio, so back in the analogue days people didn't take the effort of doing so.

Now since everything is digital, it's easy to have filters with linear phase response.

Also any general purpose audio codec has very little reason to mess with the phase, so the data will likely go through given sufficiently high bit rates.

BTW back in the analogue days there was a variety of ways to deal with non-linear phase responses which you could have when the audio was transmitted via television or the radio. The WDR Computer Club (West Germany) had a device which would cup off the overtones of the tape signal. That way they didn't need to care as much about what the overtones contributed to the signal. In (communist) East Germany, the solution was to broadcast the signal in stereo, loud on one channel and with 10dB attenuation on the other one.

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