ApolloHoax.net
Apollo Discussions => The Reality of Apollo => Topic started by: darren r on January 09, 2016, 11:48:02 AM
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I heard on the radio yesterday about some British school kids who had spoken to Tim Peake on the ISS by radio, and there was a story a while back about a radio ham, in Wales, I think, who'd managed to make impromptu contact with the station as it passed overhead.
Which set me wondering - did any hams ever make contact with any of the Apollo missions? Would it have been possible to do so?
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I heard on the radio yesterday about some British school kids who had spoken to Tim Peake on the ISS by radio, and there was a story a while back about a radio ham, in Wales, I think, who'd managed to make impromptu contact with the station as it passed overhead.
Which set me wondering - did any hams ever make contact with any of the Apollo missions? Would it have been possible to do so?
I don't think it ever happened, though I don't see any reason why it would not have been technically possible. There was ham radio operator who listened in on Apollo 11 surface operations on VHF. He was Larry Baysinger (W4EJA) of Louisville KY.... http://legacy.jefferson.kctcs.edu/observatory/apollo11/
There were others who did similar things on S-Band
AFAIK the first Ham operator to make a call from space was on one of the early Shuttle missions (STS-10?)
ETA: It was STS-09
http://science.nasa.gov/science-news/science-at-nasa/2000/ast21aug_1/
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Yes, the first "ham in space" was Dr. Owen Garriott, W5LFL, flying on STS-9. He also flew on Skylab 3 (the 2nd crew). I've met him a few times; a very nice guy with, as you might suspect, many great stories to tell.
Several hams passively received Apollo on S-band; they did not transmit. Their stories are written up in various places but I could gather them here if there's interest. They could receive the S-band FM voice subcarrier on the PM downlink but their antennas would have been far too small to receive S-band FM, used during video transmissions. Baysinger was therefore wise to listen on UHF instead for Neil Armstrong's backpack transmitter.
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If any hams had transmitted on any Apollo frequencies, they would have been in big trouble.
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Yes, the first "ham in space" was Dr. Owen Garriott, W5LFL, flying on STS-9.
Only if you don't count this Ham!!
(https://timedotcom.files.wordpress.com/2014/10/astrochimps-011.jpg?quality=75&strip=color&w=422)
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Yes, the first "ham in space" was Dr. Owen Garriott, W5LFL, flying on STS-9.
Only if you don't count this Ham!!
(https://timedotcom.files.wordpress.com/2014/10/astrochimps-011.jpg?quality=75&strip=color&w=422)
I had forgotten about him, and Enos into orbit.
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If any hams had transmitted on any Apollo frequencies, they would have been in big trouble.
Yes. Not only are the Apollo frequencies outside any amateur frequency allocation, the spacecraft transponders are designed to only lock on to one uplink signal at a time.
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If any hams had transmitted on any Apollo frequencies, they would have been in big trouble.
Yes. Not only are the Apollo frequencies outside any amateur frequency allocation, the spacecraft transponders are designed to only lock on to one uplink signal at a time.
Yes, contact with off-the-shelf equipment would not be accomplished and most hams (I was active for quite a while) would be responsible enough to not try but even without being successful, someone messing around with an attempt might be detected and draw the wrath of the FCC.
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It would also take a lot of power, by ham standards. At the time we were limited to 1 kilowatt DC input to the final amplifier, which meant no more than maybe 500-700 W of RF to the antenna. (It's now 2 kW RF to the antenna). The Apollo ground stations, IIRC, ran several tens of kilowatts to fairly large dishes, and the spacecraft transponders were not particularly sensitive because they didn't need to be.
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I don't think it ever happened, though I don't see any reason why it would not have been technically possible. There was ham radio operator who listened in on Apollo 11 surface operations on VHF. He was Larry Baysinger (W4EJA) of Louisville KY.... http://legacy.jefferson.kctcs.edu/observatory/apollo11/
There were others who did similar things on S-Band
That is fantastic!
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I don't think it ever happened, though I don't see any reason why it would not have been technically possible. There was ham radio operator who listened in on Apollo 11 surface operations on VHF. He was Larry Baysinger (W4EJA) of Louisville KY.... http://legacy.jefferson.kctcs.edu/observatory/apollo11/
There were others who did similar things on S-Band
That is fantastic!
Another non NASA third party that hoaxers continue to ignore.
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I don't think it ever happened, though I don't see any reason why it would not have been technically possible. There was ham radio operator who listened in on Apollo 11 surface operations on VHF. He was Larry Baysinger (W4EJA) of Louisville KY.... http://legacy.jefferson.kctcs.edu/observatory/apollo11/ (http://legacy.jefferson.kctcs.edu/observatory/apollo11/)
There were others who did similar things on S-Band
That is fantastic!
Another non NASA third party that hoaxers continue to ignore.
Not exactly. The hoax nuts contend that because Baysinger and others didn't *continuously track the missions to and from the moon* means that they didn't go anywhere other than to LEO.
Here's a bit from one of the hoax nuts that I read somewhere recently. I copied and saved it, because it offended me so.
There are some known Ham radio operators who attest to having picked up signals from Apollo (Paul Wilson, Richard Knadle, Larry Baysinger, Sven Grahn), but none of them can attest to having tracked these probes all the way to the moon and back. Grahn for example only testifies to having picked up signals from Apollo 17 when it was in earth orbit, when it was allegedly on the moon and alledgedly in lunar orbit. He never confirms that he ever tracked it when it was allegedly on the moon. He openly admits to not tracking it the whole way there and back. Baysinger only received communications from Apollo 11 during the alleged moonwalk, again not all the way to the moon and back. Wilson & Knadle received signals from a diversity of Apollo missions, but again only when the crafts were allegedly in lunar orbit – an exception being Apollo 15 in which they received a handful of signals on the alleged flight home.
This sort of thing absolutely infuriates me. How they can twist things to suit their own limited knowledge, when a little bit less effort in a different direction would educate them well enough for them to understand the wonder of the entire thing.
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I don't think it ever happened, though I don't see any reason why it would not have been technically possible. There was ham radio operator who listened in on Apollo 11 surface operations on VHF. He was Larry Baysinger (W4EJA) of Louisville KY.... http://legacy.jefferson.kctcs.edu/observatory/apollo11/
There were others who did similar things on S-Band
That is fantastic!
Very much so, especially when you consider that those EVA suit transmitters would have only been designed to operate over a short distance of a few hundred metres. Maybe ka9q will have a better idea, but with suit power consumption at a premium, I think the transmitter output power is likely to have been just a few watts at the most, perhaps even in the order of milliwats!
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Not exactly. The hoax nuts contend that because Baysinger and others didn't *continuously track the missions to and from the moon* means that they didn't go anywhere other than to LEO.
Now you see, the very fact that they would state that shows that they are completely ignorant of Larry's account and of the dynamics of tracking an object in LEO.
Larry used a corner reflector, which is a directional antenna. He had to keep pointing it AT THE MOON to get reception as the moon drifted across the sky (and out of the main lobe of his antenna). Tracking an object in LEO is a far different prospect. The moon tracks across the sky at about 15°/hr while an object in LEO tracks at a few degrees per second.
VHF is "line-of-sight" at the frequencies being used (250 - 300 MHz), and an object in LEO only remains "line-of-sight" (above the "local radio horizon") for a minute or two, but Larry was listening to the Apollo 11 lunar surface transmissions for at least five minutes.... that would be impossible for a ground based receiver if the transmissions were originating in LEO!
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Not exactly. The hoax nuts contend that because Baysinger and others didn't *continuously track the missions to and from the moon* means that they didn't go anywhere other than to LEO.
Now you see, the very fact that they would state that shows that they are completely ignorant of Larry's account and of the dynamics of tracking an object in LEO.
Larry used a corner reflector, which is a directional antenna. He had to keep pointing it AT THE MOON to get reception as the moon drifted across the sky (and out of the main lobe of his antenna). Tracking an object in LEO is a far different prospect. The moon tracks across the sky at about 15°/hr while an object in LEO tracks at a few degrees per second.
VHF is "line-of-sight" at the frequencies being used (250 - 300 MHz), and an object in LEO only remains "line-of-sight" (above the "local radio horizon") for a minute or two, but Larry was listening to the Apollo 11 lunar surface transmissions for at least five minutes.... that would be impossible for a ground based receiver if the transmissions were originating in LEO!
^^All of which is a perfectley sensible explanation.
However, yer average HB will know nothing about radio transmission (if they did then they would be using such a ridiculous argument), which means that they will handwave away the explanation.
Another approach would be to tackle the loaded question that is in their central assumption- that is, that there must have been a continuous tracking of the craft from the Earth to the Moon. That is a ridiculous proposition. If my friend brings me back a picture of him standing on top of the Empire State Building from his recent trip to New York, then why on Earth would I claim that the trip was hoaxed unless he provided evidence that his plane was tracked the whole way from our local airport to the States, every foostep through the airport, every taxi ride, every subway journey- all were tracked. He would certainly be right to think that I was off my rocker, especially if he gave me souvenirs, videos of him eating bagels in Times Square, a ticket from a Broadway show that he had seen etc etc.
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However, yer average HB will know nothing about radio transmission (if they did then they would be using such a ridiculous argument), which means that they will handwave away the explanation.
In those situations, I am often torn between deciding whether or the HB concerned is handwaving away the explanation because
a. it doesn't fit with their carefully constructed and distorted world-view, or
b. they are too stupid to understand it.
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In those situations, I am often torn between deciding whether or the HB concerned is handwaving away the explanation because
a. it doesn't fit with their carefully constructed and distorted world-view, or
b. they are too stupid to understand it.
It's often the case that these options aren't mutually exclusive. Many times they hold a distorted world-view because they are stupid. For example, Dak-Dak and Allan Weisbecker.
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There are some known Ham radio operators who attest to having picked up signals from Apollo (Paul Wilson, Richard Knadle, Larry Baysinger, Sven Grahn), but none of them can attest to having tracked these probes all the way to the moon and back. Grahn for example only testifies to having picked up signals from Apollo 17 when it was in earth orbit, when it was allegedly on the moon and alledgedly in lunar orbit. He never confirms that he ever tracked it when it was allegedly on the moon. He openly admits to not tracking it the whole way there and back. Baysinger only received communications from Apollo 11 during the alleged moonwalk, again not all the way to the moon and back. Wilson & Knadle received signals from a diversity of Apollo missions, but again only when the crafts were allegedly in lunar orbit – an exception being Apollo 15 in which they received a handful of signals on the alleged flight home.
This sort of thing absolutely infuriates me. How they can twist things to suit their own limited knowledge, when a little bit less effort in a different direction would educate them well enough for them to understand the wonder of the entire thing.
Others have shown arguments that you may use to debunk this type of belief. Myself, I think the most convincing part is that the antennas must be pointed toward the Moon to receive signals, no matter how/when the spacecraft travelled to the moon.
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Not exactly. The hoax nuts contend that because Baysinger and others didn't *continuously track the missions to and from the moon* means that they didn't go anywhere other than to LEO.
Now you see, the very fact that they would state that shows that they are completely ignorant of Larry's account and of the dynamics of tracking an object in LEO.
Larry used a corner reflector, which is a directional antenna. He had to keep pointing it AT THE MOON to get reception as the moon drifted across the sky (and out of the main lobe of his antenna). Tracking an object in LEO is a far different prospect. The moon tracks across the sky at about 15°/hr while an object in LEO tracks at a few degrees per second.
VHF is "line-of-sight" at the frequencies being used (250 - 300 MHz), and an object in LEO only remains "line-of-sight" (above the "local radio horizon") for a minute or two, but Larry was listening to the Apollo 11 lunar surface transmissions for at least five minutes.... that would be impossible for a ground based receiver if the transmissions were originating in LEO!
^^All of which is a perfectley sensible explanation.
However, yer average HB will know nothing about radio transmission (if they did then they would be using such a ridiculous argument), which means that they will handwave away the explanation.
Another approach would be to tackle the loaded question that is in their central assumption- that is, that there must have been a continuous tracking of the craft from the Earth to the Moon. That is a ridiculous proposition. If my friend brings me back a picture of him standing on top of the Empire State Building from his recent trip to New York, then why on Earth would I claim that the trip was hoaxed unless he provided evidence that his plane was tracked the whole way from our local airport to the States, every foostep through the airport, every taxi ride, every subway journey- all were tracked. He would certainly be right to think that I was off my rocker, especially if he gave me souvenirs, videos of him eating bagels in Times Square, a ticket from a Broadway show that he had seen etc etc.
Precisely this is the refutation I personally have used in the past. Ask a hoax nut if they've ever visited the mall, for example. They respond in the affirmative. I say "How do I know that? I didn't see you drive on every street, make every turn, enter the parking lot, walk to the door, etc." Most of them either get it, or they want to get argumentative "That's not the same thing, I didn't have a multibillion dollar budget from taxes stolen from taxpayers and all this fake space hardware" etc. At which point, the thought "you must want to remain stupid" comes to mind. That's handwaving at its finest.
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Ask a hoax nut if they've ever visited the mall, for example. They respond in the affirmative. I say "How do I know that? I didn't see you drive on every street, make every turn, enter the parking lot, walk to the door, etc." Most of them either get it, or they want to get argumentative "That's not the same thing, I didn't have a multibillion dollar budget from taxes stolen from taxpayers and all this fake space hardware" etc. At which point, the thought "you must want to remain stupid" comes to mind. That's handwaving at its finest.
And why do they refuse to educate themselves? I think with many, it's because other hoax believers is all they have that they can call 'friends' and that belief is all they have to give them any sense of self-worth. It's really quite sad.
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And why do they refuse to educate themselves? I think with many, it's because other hoax believers is all they have that they can call 'friends' and that belief is all they have to give them any sense of self-worth. It's really quite sad.
In my estimation, most have a lot invested in the hoax and to do an about face and admit error is too much for most if not all.
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Very much so, especially when you consider that those EVA suit transmitters would have only been designed to operate over a short distance of a few hundred metres. Maybe ka9q will have a better idea, but with suit power consumption at a premium, I think the transmitter output power is likely to have been just a few watts at the most, perhaps even in the order of milliwats!
About 300 milliwatts. He received Armstrong's suit transmitter but heard Aldrin as well because Aldrin transmitted to a receiver in Armstrong's PLSS, which added Armstrong's voice and telemetry and retransmitted their sum to the receiver in the LM.
Why didn't the LMP transmit directly to the LM? Because the original spec called for only one astronaut to be on the surface at a time. When this was changed to two-man EVAs, it was easier to build a relay into one of the PLSSes than to add another receiver to the LM.
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Why didn't the LMP transmit directly to the LM? Because the original spec called for only one astronaut to be on the surface at a time. When this was changed to two-man EVAs, it was easier to build a relay into one of the PLSSes than to add another receiver to the LM.
Seems odd that NASA planned on a two manned lander with only one on the surface at a time. The planners did a poor job of mission specs when they came up with that one.
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About 300 milliwatts. He received Armstrong's suit transmitter but heard Aldrin as well because Aldrin transmitted to a receiver in Armstrong's PLSS, which added Armstrong's voice and telemetry and retransmitted their sum to the receiver in the LM.
A 300mW omnidirectional voice transmission heard over a distance of 384,000 km.... truly remarkable!!
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A 300mW omnidirectional voice transmission heard over a distance of 384,000 km.... truly remarkable!!
Yes, and the truly ironic thing is that had Baysinger tried to receive the signal that was intended to reach Earth, he would have failed.
The LM had only a single S-band transmitter. It could operate in two modes: PM (phase modulation) and FM (frequency modulation). PM was the normal mission mode. It had a strong carrier component that was used for continuous Doppler velocity tracking, with subcarriers for narrowband FM voice and PCM (digital) telemetry. It could also loop back a ranging signal when enabled. All these signals (except ranging) were narrowband, meaning that the receivers on Earth would not let in a lot of thermal noise, which is proportional to bandwidth. Several hams did successfully receive the Apollo S-band PM transmissions on later flights with backyard dishes.
But PM could not carry wideband video; that's what FM was for. FM has the property that if you go wideband, meaning that you occupy a RF bandwidth considerably wider than the information you're sending, you get a substantial increase in recovered signal-to-noise ratio provided that your received signal is stronger than a given threshold. Otherwise you get nothing. (This is why FM radio sounds better than AM, but degrades rapidly as the signal weakens.)
Eagle was transmitting FM and video during the EVA, and to get that wideband signal above threshold very large receiving dishes were required (see The Dish). Anything Baysinger could have built would have gotten nothing at all.
The transmitter in Armstrong's PLSS generated only 300 mW into an omnidirectional antenna, but it was narrowband AM and Baysinger was able to capture it with his homemade antenna. It was by no means strong, but it was definitely there. Had he tried to listen for Aldrin's transmitter (which was intended for Armstrong's relay receiver) he also would have failed because that transmitter used FM, and the signal would have been below Baysinger's receiver threshold. So he did his homework and picked the right problem to solve.
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I assume that all this information was published prior to the mission. I know what assumptions do,however.
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Why didn't the LMP transmit directly to the LM? Because the original spec called for only one astronaut to be on the surface at a time. When this was changed to two-man EVAs, it was easier to build a relay into one of the PLSSes than to add another receiver to the LM.
Seems odd that NASA planned on a two manned lander with only one on the surface at a time. The planners did a poor job of mission specs when they came up with that one.
Not really. Remember that all nine Gemini EVAs had one person outside with one remaining in the spacecraft.
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Why didn't the LMP transmit directly to the LM? Because the original spec called for only one astronaut to be on the surface at a time. When this was changed to two-man EVAs, it was easier to build a relay into one of the PLSSes than to add another receiver to the LM.
A trio of questions:
Was this the aim for all APollo EVAs initially, or just Apollo 11? (I find it hard to imagine an H or J mission with just one person outside)
When did the change from one person to two people on the lunar surface happen?
Did post Apollo 11 EVAs also relay through the commander's PLSS?
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Why didn't the LMP transmit directly to the LM? Because the original spec called for only one astronaut to be on the surface at a time. When this was changed to two-man EVAs, it was easier to build a relay into one of the PLSSes than to add another receiver to the LM.
Seems odd that NASA planned on a two manned lander with only one on the surface at a time. The planners did a poor job of mission specs when they came up with that one.
Not really. Remember that all nine Gemini EVAs had one person outside with one remaining in the spacecraft.
Yes, but that was a very different circumstance.
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Why didn't the LMP transmit directly to the LM? Because the original spec called for only one astronaut to be on the surface at a time. When this was changed to two-man EVAs, it was easier to build a relay into one of the PLSSes than to add another receiver to the LM.
Seems odd that NASA planned on a two manned lander with only one on the surface at a time. The planners did a poor job of mission specs when they came up with that one.
Not really. Remember that all nine Gemini EVAs had one person outside with one remaining in the spacecraft.
Yes, but that was a very different circumstance.
In what way?
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Why didn't the LMP transmit directly to the LM? Because the original spec called for only one astronaut to be on the surface at a time. When this was changed to two-man EVAs, it was easier to build a relay into one of the PLSSes than to add another receiver to the LM.
Seems odd that NASA planned on a two manned lander with only one on the surface at a time. The planners did a poor job of mission specs when they came up with that one.
Not really. Remember that all nine Gemini EVAs had one person outside with one remaining in the spacecraft.
Yes, but that was a very different circumstance.
In what way?
1. Zero Gravity, somebody to drag the partner back into the hatch.
2. No PLSS, but connected to the spacecraft, someone needs to monitor the environment.
3. Job tasks related to one, whereas two were required for setup of different experiments.
Please understand, I'm not arguing with you just stating that to land two men on the moon and have one inside the landing craft seems poor planning.
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Why didn't the LMP transmit directly to the LM? Because the original spec called for only one astronaut to be on the surface at a time. When this was changed to two-man EVAs, it was easier to build a relay into one of the PLSSes than to add another receiver to the LM.
Seems odd that NASA planned on a two manned lander with only one on the surface at a time. The planners did a poor job of mission specs when they came up with that one.
Not really. Remember that all nine Gemini EVAs had one person outside with one remaining in the spacecraft.
Yes, but that was a very different circumstance.
In what way?
1. Zero Gravity, somebody to drag the partner back into the hatch.
2. No PLSS, but connected to the spacecraft, someone needs to monitor the environment.
3. Job tasks related to one, whereas two were required for setup of different experiments.
Please understand, I'm not arguing with you just stating that to land two men on the moon and have one inside the landing craft seems poor planning.
If it was poor planning (or better, not ideal), that may have been one reason why it was changed.
However, keep in mind it it depends on how risks are assessed. For example if the lunar surface is deemed hazardous then exposing two people to that hazard is twice the risk of exposing one if the second person offers no meaningful safety margin.
I learned this lesson while planning some underwater operations under hazardous conditions with a commercial diving firm. It was deemed safer to have one diver on the seabed in constant communications and a second one standby on the surface for any rescue than it was to have both in the water at the same time. There are so many factors, some quite subtle at play here.
At first impressions it would have been very difficult to get an incapacitated astronaut back into the LM, even with help. A second person could help in sharing life support in the event of a failure or leak, or if an astronaut had difficulty getting getting up after a fall. Maybe there were still lurking fears that astronauts would disappear into deep pits of Gold dust. Wasn't there a thread a while back discussing how Armstrong was initially secured to the LM by a safety line against such an occurrence?
What documentation is there for the change from one person to two person EVAs from the LM? How did this related to the hatch opening direction decision, forcing the commander to be the one to go out first, or do a solitary EVA?
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Was this the aim for all APollo EVAs initially, or just Apollo 11? (I find it hard to imagine an H or J mission with just one person outside)
I don't think they were thinking that far ahead.
You do have to consider that communications between the two astronauts was more important than comm between either and the earth. That ruled out a LM relay between the two astronauts; they had to talk direct in case they were too far from the LM. By having the CDR relay the LMP to the LM, direct communications between the two could be maintained with just one VHF receiver on the LM.
Nowadays you'd use a mesh network where every station (LM, LRV, CDR, LMP) transmits and receives on a single channel and they automatically relay high speed digital packets in all directions as conditions permit. Or everyone would have two mesh radios on separate channels for redundancy.
When did the change from one person to two people on the lunar surface happen?
I know I've seen that discussed (that's how I know the reason for the relay) but I can't remember where.
Did post Apollo 11 EVAs also relay through the commander's PLSS?
Yes, all of them. The only change came with Apollo 15, when they had the relay package on the rover in addition to the LM. The two were almost functionally identical, including the ability of the rover relay to transmit either PM (for voice) or FM (for voice/video) S-band to earth. PM had much better link margin, just as it did from the LM, so it was used through a low gain antenna during drives. FM required the LRV to be parked and the high gain antenna manually pointed at the earth.
About the only difference is that the LRV PM transponder was not coherent, as it listened to the same uplink from earth as the LM but transmitted on its own downlink frequency. (The uplink and downlink frequencies in a coherent transponder have to be in a specified ratio of 221/240 for S-band). The ground could therefore select a return (astronaut->Houston) link by just switching earth receivers.
Selecting the forward link was a little more complex. Uplink voice was sent to the LM (and CSM) as NBFM on a 30 kHz subcarrier. A separate subcarrier of 124 kHz was used for the LRV, so the ground could select a relay by just modulating the appropriate uplink subcarrier. The LM and LRV transmitted to the astronauts on the same frequency, but voice-activated switching (VOX) keyed each transmitter only when the associated receiver was active; this avoided interference on the moon between the two VHF transmitters.
Commands were sent to both the LM and LRV on a 70 kHz subcarrier, but they could be addressed digitally.
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thanks!
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Sure.
That independent comm relay on the LRV really saved their bacon on Apollo 16 when the LM high-gain antenna failed. They used backup voice mode (direct PM on the main S-band carrier) and omni antennas during the landing and ascent but it was weak and often hard to understand. Video would have been impossible.
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Sure.
That independent comm relay on the LRV really saved their bacon on Apollo 16 when the LM high-gain antenna failed. They used backup voice mode (direct PM on the main S-band carrier) and omni antennas during the landing and ascent but it was weak and often hard to understand. Video would have been impossible.
I didn't know that happened, so they just relayed the signal to the LM and used the big antenna to transmit the voice/images back to the MDSN?
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The steerable high-gain antenna on the upper right side of the Apollo 16 did not deploy; one of the pins used to immobilize and protect it during launch failed to disengage when commanded. You can easily tell you're looking at the Apollo 16 LM in pictures: the high gain antenna is pointed directly back at the western horizon instead of up at the earth.
During landing and ascent, they still had to use the LM comm system so they used the omni antennas (small conical corkscrews, one on front, one on back) and often the "backup voice" mode. This sounds noticeably different from the normal voice mode because the backup mode is essentially AM. (It's actually direct phase modulation or PM of the voice on the S-band carrier, but the modulation level is so low that mathematically it is very similar to AM).
The normal voice mode is narrowband FM on a subcarrier on the main PM S-band carrier (FM when video is being transmitted). As an AM signal gets weaker, the noise stays constant and the voice sinks into it. As an FM signal gets weaker, you first hear "popcorn" noise, then it gets louder and eventually blots out the voice.
During Apollo 16 surface operations, the partly failed LM comm system was simply left unused (except to monitor LM telemetry, which had to be sent at a low data rate) and the independent comm system on the LRV was used instead to talk to the astronauts. It had its own high gain antenna that could be pointed manually at earth, so they still had full video coverage of the EVAs.
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The steerable high-gain antenna on the upper right side of the Apollo 16 did not deploy; one of the pins used to immobilize and protect it during launch failed to disengage when commanded. You can easily tell you're looking at the Apollo 16 LM in pictures: the high gain antenna is pointed directly back at the western horizon instead of up at the earth.
During landing and ascent, they still had to use the LM comm system so they used the omni antennas (small conical corkscrews, one on front, one on back) and often the "backup voice" mode. This sounds noticeably different from the normal voice mode because the backup mode is essentially AM. (It's actually direct phase modulation or PM of the voice on the S-band carrier, but the modulation level is so low that mathematically it is very similar to AM).
The normal voice mode is narrowband FM on a subcarrier on the main PM S-band carrier (FM when video is being transmitted). As an AM signal gets weaker, the noise stays constant and the voice sinks into it. As an FM signal gets weaker, you first hear "popcorn" noise, then it gets louder and eventually blots out the voice.
During Apollo 16 surface operations, the partly failed LM comm system was simply left unused (except to monitor LM telemetry, which had to be sent at a low data rate) and the independent comm system on the LRV was used instead to talk to the astronauts. It had its own high gain antenna that could be pointed manually at earth, so they still had full video coverage of the EVAs.
After spending about 30 minutes at ALSJ, searching for images that have LM(A lot of them), I now "see" that the high gain antenna is not deployed beside the LM as in the other missions, probably because of the failure. I never noticed the missing deployment before. As I said earlier I'm learning facts that I didn't realize existed that were unknown to me.