With the 44th anniversary of the launch of Voyager I, [Daniel] decided to use GNU Radio to decode Voyager data. The data isn’t live, but a recording from the Green Bank Telescope. The 16 GB file is in GUPPI format which stores raw IQ samples.
The file contains 64 frequency channels of just under 3MHz each. The signal of interest is in one channel, so it is easy to just throw away the rest of the data.
A Python block manipulates the file and provides a data source. Once you have that, the rest is pretty standard processing although, as you might expect, the signal is weak even with a 100 meter antenna. Large Fourier transforms do the trick.
Then it is a matter for decoding, although there are some obscure keys needed to pull the data out correctly. In the end, it all shows up and it is a great detective story of how to go through the data step-by-step.
It is amazing what Voyager does with old tech. If you need a bootstrap on GNU Radio, check out our series.
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