The TV signal from Apollo 11 had limited bandwidth, and an oddball format was used to send and convert the signal.

All of the modern SSTV demos I've seen on YouTube seem to take around a minute to transfer one frame.

In 1969, if you had receiver big enough on earth to listen to Apollo 11's radio signal, would the SSTV tones be audible? And would it be a similar sound to modern SSTV formats?

I can't find much information on this, and it seems no recordings exist sadly.

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    $\begingroup$ @Uwe: The "tones", going by the video, appear to be the actual signal for the image. $\endgroup$ – Nathan Tuggy Mar 9 '19 at 22:35
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    $\begingroup$ See this NASA paper on page 7. "A 320 horizontal progressive line, 10 frame per second, format was chosen to fit in this space. This slow-scan format used only one-tenth of the 5 MHz bandwidth of the 525 interlaced lines, 30 frames per second format that was standard for television in the United States at the time." So the SSTV signal bandwidth was about 500 kHz, much more than hearable. The 10 frames per second was too low to be heard but the 3.2 kHz line frequency may be hearable. $\endgroup$ – Uwe Mar 9 '19 at 23:10
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    $\begingroup$ @Uwe Thanks! That great PDF answers my question. Hopefully one day someone recreates a software version of the 10fps encoder/decoder, it would be interesting to see it work in realtime. $\endgroup$ – S. Low Mar 11 '19 at 13:58

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