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Open-source communications by bouncing signals off the Moon

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Re: Open-source communications by bouncing signals off the Moon

#42

Post by shevy-java »

shakna wrote: post #29
whatsupdog wrote: post #27

For someone not well versed with the terminology, can someone please tell what kind of bitrate this can provide? In bytes per second.

It's not even a byte per second. The latency of the distances involved mean you're looking at around two seconds per round trip, plus a little extra because of the fuzziness of radio in space and absolutely everything that can distort it. There's a lot of math that goes into selecting the right bit-width for the signal, which I ain't doing here and now [0], but most 24dB things tend to be 32bit for reasons. The array…

Ok so ... moon is slow going.

Re: Open-source communications by bouncing signals off the Moon

#44

Post by djexjms »

shakna wrote: post #29
whatsupdog wrote: post #27

For someone not well versed with the terminology, can someone please tell what kind of bitrate this can provide? In bytes per second.

It's not even a byte per second. The latency of the distances involved mean you're looking at around two seconds per round trip, plus a little extra because of the fuzziness of radio in space and absolutely everything that can distort it. There's a lot of math that goes into selecting the right bit-width for the signal, which I ain't doing here and now [0], but most 24dB things tend to be 32bit for reasons. The array…

This is obviously incorrect. Latency is not the same as bandwidth. EME hobbyists will bounce voice signals off the moon.

Re: Open-source communications by bouncing signals off the Moon

#45

Post by topspin »

lll-o-lll wrote: post #20
dreamcompiler wrote: post #19

If the goal is only to communicate with people on the other side of the world, HF ionosphere skip can do that with cheap 100-year-old technology (although transistors make it easier). I assume the goal is to do something cooler than that.

> I assume the goal is to do something cooler than that. Yes. Bounce the signal off the moon. The moon .

Hams bounce signals off of everything. Aircraft scatter, for example. Probably the coolest is using the ion trails of meteorites. When meteors punch through the atmosphere, they create ionized trails. These trails can reflect RF signals. Some of these happen to be optimal at low VFH frequencies, and hams make contacts using frequencies that ordinarily don't work beyond line of sight.

Re: Open-source communications by bouncing signals off the Moon

#48

Post by henrikf »

That's very impressive and I'm even more impressed if you can manage to sell tiles at that low price.

PA looks suspiciously similar to SE5004L. I just needed some for my own projects but every distributor is out of stock. I wonder if this is where all of them went?

Re: Open-source communications by bouncing signals off the Moon

#49

Post by but-vaccum »

shakna wrote: post #40
ant6n wrote: post #36

Earlier quoted context omitted.

I dont get it, How does latency affect bandwidth here?

Because we're not stationary, and nor is the moon. Latency means greater dispersion, and lower successful return rates.

Latency itself doesn't mean squat. Throw a pair of trancievers into deep space and no relative motion and all bitrate limiting factors (dispersion, multipath, doppler shift- I'm sure there's more) disappear besides SNR/inverse square and retransmission.

Going beyond intuition- secondary reasoning says since GSO bandwidth & bitrate is acceptable for TV and sat phones by the hundred.

Tercheriary is we have/had a few hundred bps from Voyager II and that's a might bit further out than the moon, and it was called out that using an 80meter dish it could be pushed to a little over 1kbps- which means at some point inverse square becomes the only non-neglegiable factor.

So please, explain with something besides repeatedly saying "latency." Even if I'm wrong, they're strong enough counters to deserve more than a single word.

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