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Bouncing a LoRa message off the moon

electronics360.globalspec.com

11–20 of 71 posts

Re: Bouncing a LoRa message off the moon

#11
post #7

Earlier quoted context omitted.

Moonbounce isn't practical for any real application nowadays. It's a fun experiment and a PR stunt.

Why isn't it practical? Background noise makes it unreliable?

Because the moon is 238,900 mi away. Nor does it stay locked in position. Nor is it perfectly reflective (albeit quite a high albedo) nor a perfect sphere.

Re: Bouncing a LoRa message off the moon

#13
post #3
post #2

of all the things to bounce off the moon, why a consumer IoT protocol? Alien 1: The humans are talking again. Alien 2: What did they say? Alien 1: The front door is locked.

A consumer protocol, but also way over consumer power level (350W). No wonder it's the furthest LoRa message sent. Let's bump it up to 1kW and break the record again...

1kW? Are you crazy??? Let's see 25mW, which is the maximum you are allowed to use in Germany for 868 MHz ...

Re: Bouncing a LoRa message off the moon

#14
post #7

Earlier quoted context omitted.

Moonbounce isn't practical for any real application nowadays. It's a fun experiment and a PR stunt.

Why isn't it practical? Background noise makes it unreliable?

The fact they used a 35m radio telescope as the receiver station here, and transmission powers way over legal limits for normal LoRa-like applications is a pretty good hint. You lose a crazy amount of signal with moonbounce, the effort is always easier to put into different methods instead. AFAIK it's only non-experimental use predates human-made satellites (US military, as a further channel to reach far-away war ships even if terrestrial propagation conditions are bad). If you can't use satellites, and can't have a receiver station within a few thousand miles of your transmitter, then it maybe is sort-of an option, but that's not really a situation you have anymore.

Amateur radio operators still do it, and with purpose-made codecs and really slow speeds it's not that out of reach (i.e. at least for those you don't need a radio telescope dish), but that's just because it's an interesting challenge.

Re: Bouncing a LoRa message off the moon

#16

Earlier quoted context omitted.

Just a guess: given that LoRa operates on line of sight, when trying to update a gateways with sensor status (e.g. GPS position of tracked item) the operator won't be able to get realtime reports if the gateway isn't positioned at a high enough altitude relative to the sensor. You can mitigate this by having many gateway/collectors at high points on buildings/hills, but bouncing signals off the moon seems like an int…

This is a cool stunt, but it's not at all practical for IoT communications. For one thing, it requires a big dish and a huge amount of transmission power to get a barely-distinguishable reflected signal. The other big issue is that it doesn't scale, because there's no directionality: the reflected signal will be scattered off the moon and received everywhere on the hemisphere of earth where the moon is above the hori…

it would be interesting to see where else it could've been picked up. like a scatter dispersion map

Re: Bouncing a LoRa message off the moon

#17
post #2

of all the things to bounce off the moon, why a consumer IoT protocol? Alien 1: The humans are talking again. Alien 2: What did they say? Alien 1: The front door is locked.

I think this is a pretty good thing, certainly promising: IoT protocols are by definition accessible to the general public which gives a lot of potential for future developments. Surely not with LoRa in particular, given the microscopical size of the payloads but the fact that it is possible is really promising. Just a decade ago, this would have been unthinkable for any hobbyist. Hell, even the prices of sdr's a decade ago were off the charts and today a semi-decent one to get you started costs a few bucks.

Re: Bouncing a LoRa message off the moon

#18

When it says amplified to 350W, how's that work out of interest, is that done actively with a 'power amplifier' or..?

This. I guess the big deal is supposed to be the single chip transceiver, but that's not a huge step past some small SDR units hams use. Throw 350 watts behind it and most any potato could EME.

Re: Bouncing a LoRa message off the moon

#20
post #2

of all the things to bounce off the moon, why a consumer IoT protocol? Alien 1: The humans are talking again. Alien 2: What did they say? Alien 1: The front door is locked.

I think it would be extremely neat to have a fully citizen run global p2p infrastructure that is nearly free, resilient to electrical and internet outages, and able to reach remote and distant places.
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