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Lunar DX

Steve Green NEPA

Steve Green NEPA

What would Armstrong and Aldrin have heard there on the surface from Earth, if they'd had something like a GE Superadio and were so inclined?

And Collins orbiting above them? What would he have heard? Technically, Collins would've been the first to hear (and maybe even QSL) broadcasts coming FROM the Moon.
 
radioman148 said:
stormy01 said:
A consumer radio is no match for a typical 240 dB total path loss over 238,000+ miles.

http://en.wikipedia.org/wiki/TV_and_FM_DX see section, "Earth – Moon – Earth (EME) propagation (Moonbounce)"
Click to expand...

I wonder if there was anything they could have used, or someone today could use to DX the AM band from the moon. Interesting concept as the world turns.
Click to expand...

I would imagine that little if any AM signal reaches the moon. At night, it all gets refracted back to earth (by the same mechanism that allows us land-bound listeners to DX!) and during the day, it never even gets that high because of absorption in the D layer. (same reason we can't DX during the day)

I would suggest FM and TV may work a lot better than the link suggests. Firstly, you only get half the 240dB path loss - because the DX signals only have to reach the moon, they don't have to come back. Secondly, the 240dB figure includes the severe losses the signals experience simply by being reflected by the moon. This article: http://en.wikipedia.org/wiki/EME_(communications) quotes the moon as only 7% efficient as a reflector. That inefficiency doesn't factor into the equation if the receiver is located *on* the moon and no reflection is necessary.

I think the main impediment to TV and FM DX on the moon would be interference. There may be only one station on 97.1 in Nashville, but there are hundreds across the United States and hundreds if not thousands more spread across the planet...
 
>>I think the main impediment to TV and FM DX on the moon would be interference. There may be only one station on 97.1 in Nashville, but there are hundreds across the United States and hundreds if not thousands more spread across the planet...>>

Ok so if that is the case any frequency that a moon visitor would listen to would sound like a graveyard with all the signals coming in....right?
 
radioman148 said:
>>I think the main impediment to TV and FM DX on the moon would be interference. There may be only one station on 97.1 in Nashville, but there are hundreds across the United States and hundreds if not thousands more spread across the planet...>>

Ok so if that is the case any frequency that a moon visitor would listen to would sound like a graveyard with all the signals coming in....right?
Click to expand...

I'm not sure how bad it would be - a mitigating circumstance is that transmitting antennas concentrate their power along the horizon. So when the moon is directly over Nashville, the Nashville station will be relatively weak -- it will be at its strongest as Nashville crosses the horizon, as viewed from the moon. But you'll still be well within range of a LOT of stations at the same time.
 
maybe we can locate Diet Smith...and fire up the Space Coupe to find out!
(the Dick Tracy comics in the '60s featured a story line dealing with a civilization on the moon...
remember Moon Maid...and Junior Tracy's wedding? no...?)
google "Moon Maid" and see the whole thing
 
w9wi said:
radioman148 said:
>>I think the main impediment to TV and FM DX on the moon would be interference. There may be only one station on 97.1 in Nashville, but there are hundreds across the United States and hundreds if not thousands more spread across the planet...>>

Ok so if that is the case any frequency that a moon visitor would listen to would sound like a graveyard with all the signals coming in....right?
Click to expand...

I'm not sure how bad it would be - a mitigating circumstance is that transmitting antennas concentrate their power along the horizon. So when the moon is directly over Nashville, the Nashville station will be relatively weak -- it will be at its strongest as Nashville crosses the horizon, as viewed from the moon. But you'll still be well within range of a LOT of stations at the same time.
Click to expand...

Wouldn't it be a mish-mash of weak signals?

After all, as the Earth rotates, you would quickly move in - then out - of the path of a given signal pretty quickly. Think of any single given signal almost as you would a pulsar. It passes by you pretty quickly - at some 800 miles per hour. So, it would be even more fleeting than the dx you get of weaker stations in an airplane at 35000 feet. Although some stay with you for a few minutes, a lot fade in and out rapidly. That's what I would expect to hear on the moon. You'd hear one signal fighting with every other signal on the frequency from Earth that you are within the horizontal plane of. It would be interesting, but could also be hard to ID anything.

This is one of the problems I have with the SETI concept. For one thing, you have so much signal decay from standard broadcasts that they fade to nothing within a light year. Secondly, you move in and out of the orbital plane of any given signal's generally horizontal footprint very quickly. Thirdly, unless the signal was beamed directly at Earth, there would be nothing left to hear. It's a galactic crapshoot and the fact that we've never heard anything from SETI means absolutely nothing.
 
w9wi said:
I'm not sure how bad it would be - a mitigating circumstance is that transmitting antennas concentrate their power along the horizon. So when the moon is directly over Nashville, the Nashville station will be relatively weak -- it will be at its strongest as Nashville crosses the horizon, as viewed from the moon. But you'll still be well within range of a LOT of stations at the same time.
Click to expand...

I wonder if stations with vertical (in addition to horizontal) polarization or those with circular polarization would be more easily heard there? I have read someplace that spacecraft (and often satellites) use circular polarization to overcome the effects of propagation in space and communicating with earth.

What about the International Space Station? The signals must be strong there, and they are high enough up (220 miles ~ 350 km) to receive multiple stations on just about every FM and TV frequency.
 
ISS would be another story...

Yes, signals would be VERY strong, indeed. When I hear their amateur radio downlink (145.800 +/- Doppler, if anyone is interested), it can be really, really strong -- often full scale on my radio's signal meter -- and it's only 5 Watts. But, the signal doesn't last long. ISS is moving at 17,000 mph, after all, and drops below the horizon quickly.

So, yes. There would be strong signals. And, there would be several at one time. But, ISS's footprint is small enough that some could be sorted out, I'm sure.

DE
 
Does anyone know if an astronaut has ever attempted to pick up AM, FM or TV signals from a spacecraft, or if they have not, ask one of them or NASA? Think there's any chance the astronauts have taken an MP3 player with FM up in space and tuned around?
 
stormy01 said:
Does anyone know if an astronaut has ever attempted to pick up AM, FM or TV signals from a spacecraft, or if they have not, ask one of them or NASA? Think there's any chance the astronauts have taken an MP3 player with FM up in space and tuned around?
Click to expand...

I was curious about that myself. I believe ham operators have had the chance to work a spacecraft which means we've had some radio guys up there.
 
One of my closest radio buddies and his wife used to motor periodically to Southold, a fantastic 'Jaws'-like community waaaay out on Long Island's North Fork, to do some research work at an observatory and to set up this aluminum-helmet equipment for students and lounge lizards who'd drop by during the night to record what they couldn't see in the heavens.

A few times they dragged me along in the day. I gladly went. The area had at least three wineries (Peconic, Pindar and Lenz are still vivid memories) and the classroom-like meeting room had a *piano*. So while I'd be doing my thing practicing piano with no letters written on the white keys in dry-marker, my buddy would be organizing some device that would .... *hear* .....

Jupiter?

Apparently, Jupiter itself emits this presence, somewhere on the electromagnetic spectrum, and can be 'recorded', at least on the squiggly graph paper my buddy installed. Obviously, you have to have the loop aimed right.

There was no clear legal ID, of course, and no jingle-imager to be heard, no 'The Solar System's Great Red Spot', but I saw the printout. My buddy says it was Jupiter. I take his word for it.

Does the Moon (or the Earth, for the matter of that) emit some sort of stable frequency presence on the frequency spectrum?
 
Most AM and Shortwave signals do not travel toward the surface of the moon due to the reflective properties of the Ionosphere. However, I could imagine that FM, UHF and VHF signals will travel toward the surface of the moon. But by the time the RF hits the moon, most of it is dissipated to the rest of the universe. You would have to have a very directional amplified antenna system to receive a usuable signal. And even then, the window of reception for one specific station would be short due to the rotation of the earth. Considering the amount of stations on a given broadcast frequency, you can be sure it will be a mess for the most part (just like e-skip but even more intense). I doubt that any of the Apollo moon walkers were able to bring a radio to the moon due to limitation of weight on the CM and the LM. However, there are ham operators on the Space Station. I'll bet one of the Astronauts have tried to listen to FM radio while living up there. I'm very curious now.
 
Peter Q. George (K1XRB) said:
Most AM and Shortwave signals do not travel toward the surface of the moon due to the reflective properties of the Ionosphere. However, I could imagine that FM, UHF and VHF signals will travel toward the surface of the moon. But by the time the RF hits the moon, most of it is dissipated to the rest of the universe. You would have to have a very directional amplified antenna system to receive a usuable signal. And even then, the window of reception for one specific station would be short due to the rotation of the earth. Considering the amount of stations on a given broadcast frequency, you can be sure it will be a mess for the most part (just like e-skip but even more intense). I doubt that any of the Apollo moon walkers were able to bring a radio to the moon due to limitation of weight on the CM and the LM. However, there are ham operators on the Space Station. I'll bet one of the Astronauts have tried to listen to FM radio while living up there. I'm very curious now.
Click to expand...

I also am very curious. I'd love to hear from one of the ham radio astronauts.
 
Here's a book online* that helps to explain some of what the space missions had to go through to accomplish communications. It mentions the frequencies were around 2 GHz, so that's SHF spectrum. The RF power of the radio and TV transmitters for the spacecraft and the lunar lander was very low, something on the order of 10 watts, and very high gain antennas were used: *http://tiny.cc/xEnAI
 
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