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Post by Jairo on Oct 1, 2011 16:17:40 GMT -4
Why did they use a BW video camera on the Apollo 11 EVA only? Wasn't there enough time to build the color ones, or did they just assume there would't be enough transmission band on that mission?
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Post by Jason Thompson on Oct 1, 2011 17:48:06 GMT -4
The colour TV camera for the lunar surface activity was not ready.
The TV cameras had to be specially designed and built for Apollo, because no TV camera small enough to use on a spacecraft for live broadcast actually existed when the missions were being planned. Although colour TV cameras for the missions had been made in time for Apollo 10 (and Apollo 11 had one in the spacecraft), they did not work in a vacuum. That work was still incomplete by the time of Apollo 11, so the only camera that would work on the lunar surface was black and white.
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Post by trebor on Oct 1, 2011 17:52:02 GMT -4
Bandwidth was a big issue, as was getting a camera capable of surviving the environment while needing as little power as possible.
Miniturising a colour tv camera was not a small task and I guess they took the safer option and went for the B&W for the initial landing,
You should speak to Dwight here on the forums who is an expert on the subject.
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Post by ka9q on Oct 1, 2011 23:51:38 GMT -4
Remember that an Apollo color camera was essentially a B&W camera with a spinning color wheel on the front. So to make a color camera you had to first make a B&W camera.
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Post by Kiwi on Oct 2, 2011 0:52:59 GMT -4
JayUtah has an excellent description of the TV quality at Clavius: www.clavius.org/tvqual.htmlAn important issue with the Apollo 11 lunar surface TV was that to get top-quality colour TV to earth, the S-band antenna had to be manually erected on the surface, and to video someone taking the first step onto the moon, that was impossible. |
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Post by Obviousman on Oct 2, 2011 4:45:29 GMT -4
Calling Dr Dwight! Calling Dr Dwight!
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Post by dwight on Oct 2, 2011 5:48:33 GMT -4
Hi Jairo, According to youtube "expert" hunchbacked, I never wrote any Apollo TV book, so read at your own peril: The original plans for Apollo TV were always envisioned as slow scan 320 line 10fps. When the Block II spacecraft was built the transmission equipment was actually able to handle full res TV. With the interest of Tom Stafford in having color TV on Apollo 10, the research and test was pushed forward by a number of years. However, the color cameras were only tested for in-cabin use, not for the lunar surface. In fact the first real discussion into color EVA TV was made on June 22, which left no time for testing the camera for Apollo 11. While Apollo 12 was still anticipated for a September flight, this meant that it too could have missed out on color TV from the lunar surface. However, the launch in November meant that all testing had been made and it did fly to the moon. 45 minutes after being turned on Al Bean pointed the camera at the sun and that was the end of that. There was a proposal by Westinghouse for a contingency color modification to the B&W Apollo 11 camera, but it was never used. Nevertheless it would have been interesting to see it used (without of course the scenarios envisioned for its required emergency use). The memo is found here: dl.dropbox.com/u/4960558/A11_color_test.pdf Hope that helps. Hey, maybe I did indeed write that book? |
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Post by ka9q on Oct 2, 2011 19:03:44 GMT -4
When the Block II spacecraft was built the transmission equipment was actually able to handle full res TV. Are you sure of that? The Unified S-Band downlink format put the video at baseband, under subcarriers at 1.024 MHz (telemetry) and 1.25 MHz (voice). NTSC analog TV takes about 4.5 MHz at baseband for studio quality. It could certainly be reduced at the expense of horizontal resolution. I know the later missions did extend video close to or somewhat past the subcarriers as they were sometimes visible and a fair amount of work went into cancelling them out. |
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Post by Kiwi on Oct 3, 2011 6:31:25 GMT -4
Hey, maybe I did indeed write that book Well, if it's any help, I can confirm that in November and December 2008 I proofread files for chapters 1 & 2 of a book called Live TV From the Moon by some bloke called Dwight Steven-Boniecki, and suggested a few changes that were made. My name appears in the acknowledgements. I can also confirm that the individual who appears on page 248 of the book, with the large camera and the extra chins, and who could pass as an older and stouter brother of Tom Cruise, is indeed the person whom I understand to be the author of the book. That probably means nothing at all to the hoax crowd, but ordinary mortals might accept it as some sort of evidence. ;D |
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Post by Jason Thompson on Oct 3, 2011 7:02:31 GMT -4
I think if anyone on the board would be sure of that it would be the man who wrote a book describing in detail the whole history of the use of television on Apollo missions.... |
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Post by dwight on Oct 3, 2011 8:40:28 GMT -4
When the Block II spacecraft was built the transmission equipment was actually able to handle full res TV. Are you sure of that? The Unified S-Band downlink format put the video at baseband, under subcarriers at 1.024 MHz (telemetry) and 1.25 MHz (voice). NTSC analog TV takes about 4.5 MHz at baseband for studio quality. It could certainly be reduced at the expense of horizontal resolution. I know the later missions did extend video close to or somewhat past the subcarriers as they were sometimes visible and a fair amount of work went into cancelling them out. Hi ka9q, regarding bandwidth capability of the Block II CSM - according to Bill Wood's essay on Apollo TV, "However, the final Block II CSM, developed after the tragic Apollo 1 fire, included an additional S-band downlink transmitter that was capable of handling the full video bandwidth of broadcast quality television signals. But there was neither the incentive nor the time to provide a new camera to take advantage of the increased bandwidth then available obn the CSM. Since the RCA slow-scan video camera was already flight qualified for the CSM the decision was made to use it on Apollo 7." I am fairly certain I have some documentation confirming that was indeed the case, as I recall raising my eyebrows as well when I first heard that, and decided to investigate further. Though I think its safe to say "tentative pending further investigation". Now to locate the documentation.... |
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Post by ka9q on Oct 4, 2011 1:27:28 GMT -4
Ah, I just realized you were talking about the CSM, not the LM. I was thinking about the latter, which carried only a single S-band transmitter that could operate in either PM or FM but not both. Transmitting video required FM, and if you wanted telemetry and voice you had to put those subcarriers onto the FM transmitter above the video.
The CSM had separate FM and PM transmitters that could operate simultaneously. Since voice and telemetry could remain on PM, there was no need to put those subcarriers on FM, so the entire FM bandwidth would be available for video.
That's probably another reason why color TV was added first to the CSM.
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Post by ka9q on Oct 4, 2011 16:48:55 GMT -4
I think if anyone on the board would be sure of that it would be the man who wrote a book describing in detail the whole history of the use of television on Apollo missions.... There's actually two separate systems here. The television cameras and associated gear are certainly Dwight's forte. But they connected to the Apollo telecommunication system, which I've dug into quite a bit. |
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