How did the Apollo flights communicate with Houston?

I’m curious about this because I know a moon hoax clown who is really harping on this point and it’s one of the few points that I don’t know enough about to answer. Usually his arguments just need some easy to demonstrate science but this one requires knowledge of communications I don’t have. I know arguing with a hoaxster is pointless but I’d personally like to know the answer to this one.

His argument is that he plugged a few values (gain, distance, etc) into a Friis equation calculator on some RF website and determined that the signal loss would be too great for communications. I’ve tried doing my own research into this but without any experience in radio or communications it’s more confusing than actual rocket science to me. I can’t even seem to determine whether this is something you could even figure out by inputting the correct values into Friis. Or even if he is using the correct values but I wanted to understand the formula before I started worrying about the variables. I can’t even find any information about Apollo and Friis together, all talk of communications just discuss Link Budgets. What is the relationship between these two? From the best I can tell they are either different methods of coming to the same conclusion or that the Friis equation is just one aspect of figuring up a link budget.

Does Friis take into account all the equipment involved, or is that what a link budget is for? If you can just figure it up with Friis can somebody demonstrate/explain how they did it? I found a site where somebody had created some link budgets to demonstrate how Apollo 11 achieved communications but the links to those budgets don’t work.

If there is an issue here I’d be interested to know. Simply dismissing facts and continuing to believe what I do in spite of that is what they generally do. As a result he wouldn’t listen to a rebuttal anymore than he did on all the other insane things he argued (such as thrusters not working in space without anything to “push off of”), but for my own personal knowledge I’d at least be curious in some straight dope on the subject.

Amateur radio operators sometimes talk to each other, using amateur equipment, by bouncing the signals off of the Moon.

He’s not entirely wrong. They did develop a system for lunar distances:

Yeah, I’ve read about the unified S-band but I didn’t know how it applied to the argument. I know they had it, and the basic definition, but don’t know what makes it better for communication with the moon. Just that it does. Does Friis not work with unified S-Band or something? I read that article about Apollo 11 (and a bunch of other similar articles) but they stop short of telling you “how” in any way that makes sense to me. It gives you a general idea but not anything about link budgets or Friis. I can’t see anything in there that refutes what he is saying, but as I said it might just not be apparent to me. I’ve put some effort into trying to understand this, read various articles, downloaded Apollo tech manuals, searched through some of the Apollo books I’ve read, and none of them really go too far in explaining any of this.

As for the moon bounce, I did read about that as well but I’m not sure if bouncing a ham radio signal off the moon and linking up all that telemetry is even comparable. He told me it wasn’t and I don’t have any response to that obviously.

Maybe this is just a topic I’m not going to be able to understand as a layman. Most articles are either too jargony for the layman or too simplified and basically just say “Trust us layman”. I suppose I should probably take the time to understand the topic more but in all honesty I have no need for this information other than to satisfy my own curiosity about an Apollo question.

Wait a minute, first he claims that signal loss is too great to communicate at the distance of the moon, then he admits that ham operators routinely communicate at TWICE the distance of the moon, but their communication is “not comparable” to telemetry? He needs to stick to one story. Exactly what bandwidth does he think is achievable at lunar distance? Obviously something between ham communications and S-band telemetry.

Yes, but as I said I’m so clueless in this area that I can’t dispute anything he says too much. I suspect that’s the whole reason he brought this up, or invented it, it has been his MO in every other argument but this is the first time he picked a field and used enough jargon that I have no clue how to even begin.

This is basically his argument though…

LEM Transmit Power - 30 Watts (I think he’s giving it too much power, from what I can tell it’s 20 Watts)

LEM Transmit Antenna Gain - 25 dBi

Receive Antenna Gain 67dBi (He’s using the Parkes dish as his example)

Wavelength 0.135 or 2.2Ghz

at a distance of 240k miles

He says if you input that data into this online Friis Transmission Calculator… Friis Transmission Equation Calculator

Then you get -74 dBm which he says proves communications were impossible.

No, he doesn’t.
He’s a truther. Logic & reality don’t apply to them.

27meg pdf with tons of details:

Yeah, I have that but as a 300+ page NASA document it’s hardly for the layman.

Does he also believe the entire planetary exploration program is a hoax? Because we routinely communicate with space probes and landers at distances that make the moon seem like it’s practically next door.

These hoaxers crack me up.

Common sense says that this can’t be a valid point. If it was then the supposed hoax would have been exposed long ago. Hell, it would have been exposed pretty much immediately.

Would they really have tried to fake something that was this easy to expose?

I don’t really know what he thinks on that, though he does make the distinction he isn’t a Flat Earther. I read something about how Voyager is able to communicate from further distances and using less power than the Apollo flights but I don’t remember if he had a response or if he was just able to talk his way around it. I think he just once again fell back on his Friis formula and challenged me to prove his math wrong. As long as his Friis calculator gives him that number he says he is right.

Well, common sense is sort of the problem with these people isn’t it? I made that exact point and he really didn’t care, his math is his math as far as he’s concerned. But I don’t even know if he’s using the right math problem much less if his result was correct.

If you’ve seen the link budget, how did the receiver sensitivity compare to -74 dBm? I believe the USB receiver operated with a noise temperature well below ambient of 300K and that the TV bandwidth was about 1 MHz. Thermal noise at 300K in a 1 MHz bandwidth is about -114 dBm, so they should have plenty of signal-to-noise ratio for TV transmission, if the numbers you gave are accurate.

I didn’t see a link budget, those are just the numbers he told me and said if you input them into that Friis calculator it gave you the “proof”. He hasn’t mentioned link budgets, that’s just something I found in my own reading. He just says take these numbers and insert them here and then the moon landing was a hoax.

This page gives some values for the Friis equation for a moon link to the Allen Telescope Array.

A 30cm dish antenna on the moon needs to transmit only 200 μW of power to be received.

Ask him to explain why -74 dBm means it is impossible. By my calculations, it means the signal-to-noise ratio is about 40 dB (a factor of 10,000) for a 1 MHz bandwidth signal, using his own numbers and my assumption of a 300 K noise temperature.

I sent him an email and asked him, now he’s not even saying that anymore. Now he’s just saying that with the -74 dBm it could be done but only if both dishes were perfectly aligned throughout transmission. He finds this unlikely because, using his television satellite dish as an example (that sounds like a stupid comparison but what do I know) he says if it is 1-2 degrees out of alignment then his signal is lost. Even as clueless as I am it seems like comparing his satellite dish losing reception to the equipment used for deep space communications is not a very good one. But for all I know I’m wrong on that too. At one point earlier he was saying the small S-Band antenna on the LM wouldn’t be able to get such a lock.

He’s right that the alignment is critical, especially for the Parkes antenna with a gain of 67 dB. These antennas are designed to track the sky accurately, otherwise it would be useless to make them so large.

Yeah, I knew that much from my reading of various Apollo missions. I knew Apollo 12 had a lot of issues with their S-Band antenna and that the angle of the descent was designed so the LM could keep theirs in alignment, but I just don’t know HOW difficult it is to keep it aligned now. He seems to be saying that it would be too hard to get the alignment done with that small dish. Also he’s now saying that it wouldn’t be impossible to do from moon orbit, just the surface. He says the moon’s movement would make it too hard. Seems to me that with the moon tidally locked the movement wouldn’t make that much difference. They’re not going to be rotating around to the far side or anything. In my admittedly limited experience it seems to still be just a matter of changing stations as the Earth rotates like it would be for regular spaceflight.

At this point he’s changing this argument up so much that my personal curiosity over whether or not he had a point is pretty much satisfied.