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 Moon Landing
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 Return to top of page · Post #: 1 · Written at 8:00:12 AM on 22 July 2017.
Redxm's avatar
 Location: Tamworth, NSW
 Member since 6 April 2012
 Member #: 1126
 Postcount: 466

An interesting article on how the moon landing broadcast was done.

http://www.popsci.com.au/space/space-travel/how-nasa-broadcast-neil-armstrong-live-from-the-moon,414791


Ben


 
 Return to top of page · Post #: 2 · Written at 10:34:55 AM on 22 July 2017.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 2371

The degradation of the image was not due to the transmission process.

The slow scan signals were converted to EIA 525 line 60Hz at the receiving stations, e.g. Parkes, and then sent via PMG microwave link to Canberra where they were uplinked to Intelsat.

The standards converter used at the time was the issue. Not digital (although the BBC had the technology to do this at the time) but optical. This converter was basically a CRT TV monitor with a long-persistence phosphor with a vidicon camera focused on it.

After that, the images we saw in Australia were converted from EIA to CCIR standards. I don't know if the ABC or anyone here at the time were running digital standards converters for that conversion or whether the "optical" method was used.

Anyway, now you know why it looked so crap!

The downlinked slow-scan images were apparently very clear and were recorded at Parkes onto 1" instrumentation tape in their native form by (I believe) the CSIRO. These tapes were subsequently lost. Despite an exhaustive search, they have never been found. Pity, modern techniques could resolve some amazing pictures from them.

So if anyone out there has a roll of 1" tape of unknown origin that might have once belonged to the CSIRO, maybe now's the time to get it checked!


 
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