Results 1 to 25 of 25

Thread: What's the science behind moon landing live broadcast?

  1. #1
    Join Date
    Dec 2019
    Posts
    1

    What's the science behind moon landing live broadcast?

    In an epoch where television ran through cable, in black and white, etc., where the most advanced wireless device was the walkie-talkie, they managed to send a LIVE audio signal and a LIVE video signal no more and no less than from the MOON? No cuts, no interferences, no problem at all. And they sent it to every television channel on the world, and hundreds of millions of people watched it at the same time.

    This was 1969. Today in 2019 sometimes I get no signal when I go to the countryside.
    Yesterday I was watching a live stream and it froze for 3-4 seconds every 2 minutes. And I got an optical fiber connection.

    So just... what the hell?

  2. #2
    Join Date
    May 2003
    Posts
    6,122
    Actually, cable television and videotape were not invented until the 1950's. Live broadcast television predates that by a couple decades, with the audio and video signals sent via radio waves, and continued to be used even after cable and videotape had been invented (because it was a mature technology that worked fine for many purposes, and was often cheaper and easier to implement). So that wasn't any kind of new technology invented just for Apollo. Getting a signal back from the moon requires a little extra effort, but no more so than the radio signals used to communicate with the astronauts.

    The fact that you can't get a cell signal in the countryside is because you're trying to establish two-way communication with a shorter range cell tower, rather than just receiving a broadcast signal from a high power transmission tower. And the fact that your live stream over the internet freezes up has more to do with the fact that the internet uses switched packets for sending data, and isn't really optimized for streaming video. It can do it, obviously, but sending the same video feed to thousands or millions of people at once is not something the internet is optimal at, whereas broadcast television was actually pretty close to ideal for that kind of signal.
    Conserve energy. Commute with the Hamiltonian.

  3. #3
    Join Date
    Mar 2006
    Posts
    587
    Quote Originally Posted by whatthehell View Post
    In an epoch where television ran through cable, in black and white, etc., where the most advanced wireless device was the walkie-talkie,
    Excuse me? Last I checked, most people were receiving television stations over the air by means of transmitters much more advanced than a "walkie-talkie" in 1969. According to this table, only 7% were on cable in 1970.
    http://www.tvhistory.tv/TV-VCR-Remot..._Ownership.JPG
    Quote Originally Posted by whatthehell View Post
    they managed to send a LIVE audio signal and a LIVE video signal no more and no less than from the MOON? No cuts, no interferences, no problem at all. And they sent it to every television channel on the world, and hundreds of millions of people watched it at the same time.
    They didn't send it from the moon to each individual television station, it was received using a large radio dish and the slow scan TV signal was then converted and rebroadcast to the various stations. Yes, it was entirely doable and you can calculate the link budget for yourself.
    Quote Originally Posted by whatthehell View Post
    This was 1969. Today in 2019 sometimes I get no signal when I go to the countryside.
    Your phone is not a 64 meter wide dish and when you go into the countryside you generally do not have a direct line-of-sight to the transmitting tower.
    https://en.wikipedia.org/wiki/Parkes...o_11_broadcast
    Quote Originally Posted by whatthehell View Post
    Yesterday I was watching a live stream and it froze for 3-4 seconds every 2 minutes. And I got an optical fiber connection.
    More apples and oranges. I'm pretty sure your live stream was not broadcasting at just 10 frames per second with 320 lines of resolution.
    https://en.wikipedia.org/wiki/Slow-scan_television
    We are talking about orders of magnitude difference in the required bandwidth. And there is a lot of complexity in your fiber optic connection with many points of possible failure. Not to mention inherent differences in analog vs digital video.
    Quote Originally Posted by whatthehell View Post
    So just... what the hell?
    Link budget. Here is an actual link budget calculation for the Apollo 11 EVA transmission. They had plenty of margin for an FM video signal with the 64 meter receiving dishes that they used.
    http://www.ka9q.net/crackpots/apollohoax.html

  4. #4
    Join Date
    Apr 2011
    Location
    Norfolk UK and some of me is in Northern France
    Posts
    8,960
    sure as frequencies have gone up, distance goes down. The BBC used to transit AM radio in the long wave 1500 m (actually they still do but with lower power) and you could pick that up over most of Europe but the FM bands today only go a few miles. There are stretches of the motorway network in the UK with no reception while in the old days the AM signal was everywhere with compression too so that car radios did not go inaudible in the quiet passages of music. VHF yagi antenna are used by moon bouncers to reach the moon and back, quite an achievement for amateurs but not comparable with Apollo.
    sicut vis videre esto
    When we realize that patterns don't exist in the universe, they are a template that we hold to the universe to make sense of it, it all makes a lot more sense.
    Originally Posted by Ken G

  5. #5
    Join Date
    Jul 2005
    Posts
    18,831
    For anyone interested in how it was done, I heartily recommend Spacecraft Films' Live From The Moon documentary, which explains things in detail, using original footage and new interviews of people involved.

    Grant Hutchison

  6. #6
    Join Date
    Jan 2004
    Location
    No longer near Grover's Mill
    Posts
    5,077
    The quality really wasn’t that good, especially for the earlier landings. The conversion from slow-scan was crude by today’s standards. Note that much of the “video” you can find online today was originally taken by film cameras and developed upon return from the moon.

    And of course there were problems. The first images of Armstrong on the LM ladder were upside down & Alan Bean damaging the video camera on Apollo 12 come immediately to mind.

    For a relatively lighthearted treatment of the issues at the Parkes Observatory, I recommend the movie “The Dish”.




    Sent from my iPhone using Tapatalk
    I may have many faults, but being wrong ain't one of them. - Jimmy Hoffa

  7. #7
    Join Date
    Jun 2003
    Location
    Central Florida.
    Posts
    5,965
    I don't think that any science fiction writer of the 1950s and earlier predicted that the first Moon landing would be televised live. The implementation was a step ahead of the most imaginative folks.

  8. #8
    Join Date
    Jan 2004
    Location
    No longer near Grover's Mill
    Posts
    5,077

    What's the science behind moon landing live broadcast?

    Quote Originally Posted by DonM435 View Post
    I don't think that any science fiction writer of the 1950s and earlier predicted that the first Moon landing would be televised live. The implementation was a step ahead of the most imaginative folks.
    I recall reading that there was some (early?) debate as to whether it should be televised. Unfortunately, I can’t recall the source. I believe the opposition was based on weight, and taking away time and attention from “more important” astronaut activities.



    Sent from my iPhone using Tapatalk
    I may have many faults, but being wrong ain't one of them. - Jimmy Hoffa

  9. #9
    Join Date
    Aug 2005
    Location
    NEOTP Atlanta, GA
    Posts
    3,025
    I recall reading a comment by Arthur C. Clarke (or was it Heinlein?) around that time that in all of the science fiction written about how a moon landing might take place, no one ever imagined that it would be televised. And live, to boot.

  10. #10
    Join Date
    Jul 2005
    Posts
    18,831
    Quote Originally Posted by Extravoice View Post
    I recall reading that there was some (early?) debate as to whether it should be televised. Unfortunately, I can’t recall the source. I believe the opposition was based on weight, and taking away time and attention from “more important” astronaut activities.
    Live From The Moon reports that many astronauts, and some other NASA personnel, were resistant to including TV cameras in the Apollo missions on the grounds that they'd be distractions from other tasks. Some came around as the missions progressed, but some didn't.

    Grant Hutchison

  11. #11
    Join Date
    Oct 2012
    Posts
    31
    If you're finding problems getting phone reception in the countryside I'd suggest not having anything in the way of the thing broadcasting the signal.

    What is there in the way of the signal from the moon other than a few miles of atmosphere between it and the enormous satellite dish receiving the signal?

    Some reading material here from the 60s:

    https://www.scribd.com/document/3961...ics-World-1969

    https://www.scribd.com/document/3961...ce-of-Apollo-8

    https://www.scribd.com/document/3961...Communications

  12. #12
    Join Date
    Jun 2003
    Location
    Central Florida.
    Posts
    5,965
    Quote Originally Posted by schlaugh View Post
    I recall reading a comment by Arthur C. Clarke (or was it Heinlein?) around that time that in all of the science fiction written about how a moon landing might take place, no one ever imagined that it would be televised. And live, to boot.
    One sf writer, can't remember who, dropped a comment about how the public mobbed the first moon films, boldly presuming that you might get to see the landing weeks later in a theater.

  13. #13
    Join Date
    Mar 2004
    Posts
    18,700
    I notice the OP hasn’t been back since the one post. Unless they are reading without logging in, it suggests they don’t have any actual interest in the science and technology behind the subject.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." — Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  14. #14
    Join Date
    Sep 2007
    Posts
    16,409
    Quote Originally Posted by DonM435 View Post
    One sf writer, can't remember who, dropped a comment about how the public mobbed the first moon films, boldly presuming that you might get to see the landing weeks later in a theater.
    In the time of newsreels, that would have been pretty much how things worked.
    The greatest journey of all time, for all to see
    Every mission makes our dreams reality
    And our destiny begins with you and me
    Through all space and time, the achievement of mankind
    As we sail the sea of discovery, on heroes’ wings we fly!

  15. #15
    Join Date
    Oct 2001
    Location
    Clear Lake City, TX
    Posts
    12,857
    Quote Originally Posted by Van Rijn View Post
    I notice the OP hasn’t been back since the one post. Unless they are reading without logging in, it suggests they don’t have any actual interest in the science and technology behind the subject.
    Let's hold off speculating on someone's motive in posting.
    Never attribute to malice that which can be adequately explained by ignorance or stupidity.
    Isaac Asimov

    You know, the very powerful and the very stupid have one thing in common. They don’t alter their views to fit the facts. They alter the facts to fit their views.
    Doctor Who

    Moderation will be in purple.
    Rules for Posting to This Board

  16. #16
    Join Date
    Sep 2004
    Posts
    15,637
    Quote Originally Posted by profloater View Post
    sure as frequencies have gone up, distance goes down. The BBC used to transit AM radio in the long wave 1500 m (actually they still do but with lower power) and you could pick that up over most of Europe but the FM bands today only go a few miles. There are stretches of the motorway network in the UK with no reception while in the old days the AM signal was everywhere with compression too so that car radios did not go inaudible in the quiet passages of music. VHF yagi antenna are used by moon bouncers to reach the moon and back, quite an achievement for amateurs but not comparable with Apollo.
    For illustration purposes: at low frequencies and bandwidths, with a simple antenna I can reach hundreds of meters using a full 0.01W of transmitter power. Now replace that with a good amplifier with orders of magnitude that power, and replace the 15cm 4dB omni antenna with a 64m dish. Getting the television signal back from the moon wasn't exactly the hardest challenge for the moon missions. (with all due respect for the struggles of the receiving stations; I have written an article about Honeysuckle Creek in the past...)
    With sufficient thrust, water towers fly just fine.

  17. #17
    Join Date
    Jan 2008
    Posts
    735
    Quote Originally Posted by whatthehell View Post
    In an epoch where television ran through cable, in black and white, etc., where the most advanced wireless device was the walkie-talkie, they managed to send a LIVE audio signal and a LIVE video signal no more and no less than from the MOON? No cuts, no interferences, no problem at all. And they sent it to every television channel on the world, and hundreds of millions of people watched it at the same time.

    This was 1969. Today in 2019 sometimes I get no signal when I go to the countryside.
    Yesterday I was watching a live stream and it froze for 3-4 seconds every 2 minutes. And I got an optical fiber connection.

    So just... what the hell?
    Dunno. Do you regularly wander the countryside with a 64 meter dish attached to your phone? No? Why not?

  18. #18
    Join Date
    May 2007
    Location
    Earth
    Posts
    10,308
    Back when I was in college -- in the early 1970s -- there was an article floating around (iirc, it was in IEEE's Spectrum) that technology available at that time permitted an NTSC signal to be sent and received over 200 light-years. This wouldn't be with some little Yagi sitting on a roof; the transmitter and receiver would both have very high-gain antennas, and the transmitter's power would be in the tens of megawatts..
    Information about American English usage here. Floating point issues? Please read this before posting.

    How do things fly? This explains it all.

    Actually they can't: "Heavier-than-air flying machines are impossible." - Lord Kelvin, president, Royal Society, 1895.



  19. #19
    Join Date
    May 2008
    Location
    The Netherlands
    Posts
    15,549
    For fun, have a look at NASA Technical Report Server document ID 19660028000. Digital television isn't all that modern.

    Manned spacecraft advanced digital television compression study. Volume 1 - Text Final report
    Document ID: 19660028000
    NTRS Full-Text: View Document [PDF Size: 9.7 MB]
    Abstract: Manned spacecraft advanced digital television compression study
    Publication Year: 1965
    Document Type: Technical Report
    Report/Patent Number: NASA-CR-65508
    Date Acquired: February 12, 1996
    ____________
    "Dumb all over, a little ugly on the side." -- Frank Zappa
    "Your right to hold an opinion is not being contested. Your expectation that it be taken seriously is." -- Jason Thompson
    "This is really very simple, but unfortunately it's very complicated." -- publius

    Moderator comments in this color | Get moderator attention using the lower left icon:
    Recommended reading: Forum Rules * Forum FAQs * Conspiracy Theory Advice * Alternate Theory Advocates Advice

  20. #20
    Join Date
    Jul 2006
    Location
    Peters Creek, Alaska
    Posts
    13,093
    Quote Originally Posted by Abaddon View Post
    Dunno. Do you regularly wander the countryside with a 64 meter dish attached to your phone? No? Why not?
    Quoted only as the latest example. Feel free to continue discussion but I wouldn't wait for a reply from the OP, who hasn't logged in since post #1.
    Forum Rules►  ◄FAQ►  ◄ATM Forum Advice►  ◄Conspiracy Advice
    Click http://cosmoquest.org/forum/images/buttons/report-40b.png to report a post (even this one) to the moderation team.


    Man is a tool-using animal. Nowhere do you find him without tools; without tools he is nothing, with tools he is all. — Thomas Carlyle (1795-1881)

  21. #21
    Join Date
    Dec 2011
    Location
    Very near, yet so far away
    Posts
    338
    Quote Originally Posted by whatthehell View Post
    In an epoch where television ran through cable, in black and white, etc., where the most advanced wireless device was the walkie-talkie, they managed to send a LIVE audio signal and a LIVE video signal no more and no less than from the MOON? No cuts, no interferences, no problem at all. And they sent it to every television channel on the world, and hundreds of millions of people watched it at the same time.

    This was 1969. Today in 2019 sometimes I get no signal when I go to the countryside.
    Yesterday I was watching a live stream and it froze for 3-4 seconds every 2 minutes. And I got an optical fiber connection.

    So just... what the hell?
    Are you aware that the first TV satellite was launched in 1962, some 7 years before the first moon landing?

    https://en.m.wikipedia.org/wiki/Telstar

  22. #22
    Join Date
    Jun 2003
    Posts
    1,730
    I guess given the time that has passed the OP is either not terribly interested in a reply or else has been distracted by that huge major worldwide holiday period we just went through and may be back now the new year is off and running, however:

    Quote Originally Posted by whatthehell View Post
    In an epoch where television ran through cable, in black and white, etc., where the most advanced wireless device was the walkie-talkie, they managed to send a LIVE audio signal and a LIVE video signal no more and no less than from the MOON? No cuts, no interferences, no problem at all. And they sent it to every television channel on the world, and hundreds of millions of people watched it at the same time.
    This translates, as many hoax believer argments often do, as: "in an age where things were done in this way I just made up that has no actual relation to reality but makes the real work of Apollo seem much more amazing than in fact it already was, this thing they did now seems so incredible as to be entirely implausible." In other words, the description of how televsion was done at the time of Apollo is waaaaaay off the mark. I conclude the OP was not actually around at that time. The 1960s was not that long ago. Plenty of people around can actually tell you what it was like because they lived then.

    This was 1969. Today in 2019 sometimes I get no signal when I go to the countryside.
    Yesterday I was watching a live stream and it froze for 3-4 seconds every 2 minutes. And I got an optical fiber connection.

    So just... what the hell?
    And here is the classic "this thing that bears no relation to the other thing works totally differently so how could that other thing have worked back then?" fallacious argument.

    Of course for a really good overview of the science behind the broadcast, try these:

    Live TV from the Moon

    Live TV from Orbit

  23. #23
    Join Date
    Jun 2015
    Location
    Houston
    Posts
    1,300
    Quote Originally Posted by PetersCreek View Post
    Quoted only as the latest example. Feel free to continue discussion but I wouldn't wait for a reply from the OP, who hasn't logged in since post #1.
    A seagull post then?

  24. #24
    Join Date
    Oct 2003
    Posts
    1,347
    Quote Originally Posted by bknight View Post
    A seagull post then?
    The joined on the 19th of December, posted this thread, and have not been logged in since, sure looks that way

  25. #25
    Join Date
    Oct 2001
    Location
    Clear Lake City, TX
    Posts
    12,857
    Please leave the moderation to the Moderators.
    Never attribute to malice that which can be adequately explained by ignorance or stupidity.
    Isaac Asimov

    You know, the very powerful and the very stupid have one thing in common. They don’t alter their views to fit the facts. They alter the facts to fit their views.
    Doctor Who

    Moderation will be in purple.
    Rules for Posting to This Board

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •