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Re: [ARSCLIST] NASA
--- Tom Fine <tflists@xxxxxxxxxxxxxxxxxxx> wrote:
> Richard Hess, who I
> believe is on vacation, knows more
> about the details of this because he is somewhat expert on
> instrumentation formats. But I'll take a
> stab. I think the video was high-resolution, slow-scan as it was
> transmitted and recorded. In other
> words, an hour-long spacewalk might take all night to transmit and
> record. Apparently, this format
> was re-modulated to NTSC to feed the networks. Now what I'm not
> clear on, was there a simultaneous
> low-quality feed coming live from the moon?
The moon walk was broadcast live. The signal from the moon
was 320 lines, progressive scan, 10 frames per second. *Not*
high resolution by any standard (newer than 1934) but a
higher resolution than was seen by anybody except the
technicians at the three Deep Space Tracking Network
stations. The conversion process (shooting a long-
persistence monitor with an NTSC video camera) produced
a lot of smearing and reduced the contrast range
significantly, so the already low-res picture was
even lower-res by the time anyone (except those few
engineers) saw it. The reason it was sent as a slow
scan signal was because there wasn't enough bandwidth
to reliably transmit the necessary instrument
telemetry and an NTSC television signal on the
bandwidth available.
David Breneman david_breneman@xxxxxxxxx
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