Re: Parkes hi-resTV tapes of Apollo 11 surface activity

From: Neil Gerace (geracen_at_iinet.net.au)
Date: 07/25/04 

Date: Sun, 25 Jul 2004 10:52:35 +0800

"Allen Thomson" <thomsona@flash.net> wrote in message
news:501f9880.0407240801.57a57ffb@posting.google.com...
> (I sent this to FPSpace, but thought it might be of interest here
> also.)
>
> http://www.parkes.atnf.csiro.au/apollo11/ has an interesting little
> write-up on their reception of the TV images of the initial Apollo 11
> surface operations that notes,
>
> The TV pictures from the Moon were narrow band slow-scan TV, that
> is, 10 frames per second (non-interlaced) and 320 lines per frame.
> In order to broadcast them to the waiting world, the pictures had
> to first be converted to the commercial TV standards...
>
> "For Apollo 11, an RCA scan-converter was used, which operated on
> an optical conversion principle. The pictures were displayed on a
> 10-inch black-and-white monitor and a Vidicon TK22 camera was
> pointed at the screen. As each frame of the 10 frames per second
> picture was received, it was displayed on the monitor. The camera
> was gated to scan a single field at the EIA (NTSC) rate of 1/60th
> of a second, that is it did not take a picture until the 10-inch
> monitor had completed displaying a full frame. The output of the
> camera was transmitted and simultaneously recorded on magnetic disc.
> The disc recording was then played back a further five times and
> transmitted. While the disc recorder was playing back, the monitor
> screen was blacked out and the next frame started displaying. The
> monitor had enough persistence that it retained the picture, and
> RCA built special circuits to adjust for any loss of brightness
> between the top and bottom of the picture. In this way, a 30
> frames per second (60 interlaced fields per second) TV was
> produced - with only one in six fields being live. "

Geez. Australians in this ng, see what has happened to Aussie ingenuity
since then?

>
> Then it provides a comparison of the image quality as received at
> Parkes
>
>
http://www.parkes.atnf.csiro.au/apollo11/images/Parkes_Apollo11_TV_SSTV_Polaroid_small.jpg
>
> vs what we saw on our home TVs:
>
>
http://www.parkes.atnf.csiro.au/apollo11/images/Parkes_Apollo11_TV_commercial_small.jpg
> and notes,

> Finally, there is a real teaser:
>
>
> As the video and telemetry downlink was being received at Parkes,
> it was recorded onto 1/2 inch magnetic tapes on a Mincom M22
> instrumentation recorder at a rate of 120 inches per second.
> These tapes had to be changed every 15 minutes during the whole
> period of the moonwalk.

Wow. By comparison, when did commercial videotape come into use?

> It would surely be nice if, somehow, those tapes have been perserved
> and could be located. Anybody here know how to go about finding out
> if NASA ever received copies? I imagine that the folks in Australia
> have been looking for the originals.

You could try Screensound Australia, (the former National Film and Sound
Archive):

http://www.screensound.gov.au

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