That recording was made in 2015 on a modern radio telescope, it is not from a tape.
The GP has the details wrong though: when the Voyager design was finalized in the early 70s with the Viterbi encoder, there wasn’t enough computational power to decode the signal. By the time it launched in ‘77, there was enough and it launched with the Viterbi encoder enabled.
Who knows how many of the details I misinterpreted or am misremembering, or that he was. Where did he hear it originally? Maybe a grizzled old professor who worked directly on the project? Maybe a TA who made up the whole thing?
Whether true or not, it inspired me then as it does now to strive to be a better engineer, to think outside the box, to attempt hard things.
I continue sharing it hoping that one day Cunningham's Law will take effect and someone will share the correct details. But there's also a part of me that hopes that never happens.
I'm not sure what is meant by that. Not fast enough to decode in real time? There is/was no need to do that. The transmissions would have gone to tape in any case.
Here is a link describing how to decode such a tape: https://destevez.net/2021/09/decoding-voyager-1/