Bouncing a LoRa message off the moon • Hacker News Board

Re: Bouncing a LoRa message off the moon

#31

Post by walrus01 » Mon, Dec 06, 2021, 7:33 PM UTC

Breefield wrote: post #5

jmole wrote: 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.

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…

> given that LoRa operates on line of sight

not exactly, no, one of the most common uses for LoRA is in the US 915 MHz band where it can function in a very much non line of sight environment.

Re: Bouncing a LoRa message off the moon

#32

Post by ineedasername » Mon, Dec 06, 2021, 7:35 PM UTC

YXNjaGVyZWdlbgo wrote: post #26

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I'm not sure that was the point. Either way, accounting for the doppler effect is possible. We generally know what the offset will be for a given frequency based on the moon's position in the sky. The article itself mentions that the signal behaved predictably with respect to the expected doppler shift.

Re: Bouncing a LoRa message off the moon

#33

Post by genewitch » Mon, Dec 06, 2021, 7:39 PM UTC

noman-land wrote: post #20

jmole wrote: 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.

Winlink basically does this. I'm unsure if there's software for other OS, but winlink is email-ish that is p2p on the backend, and can also be used point to point. And don't tell anyone I said this, but if you have a real hardware modem for winlink you can get 3KB/second. It works on any frequency you can tune to.

Also APRS, even though it seems like Google has a huge interest in it, is also a p2p communication network, running on 144mhz and 10mhz.

Re: Bouncing a LoRa message off the moon

#34

Post by intpx » Mon, Dec 06, 2021, 7:55 PM UTC

gh02t wrote: post #21

jmole wrote: 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.

LoRa isn't really a consumer protocol, more of an industrial one. It's mostly intended for widely distributed sensor networks.

Wasn't it designed for sending sensor data from oil wells spread out over vast swaths of land or something? I've always though of it as shortwave/vhf for packets

Re: Bouncing a LoRa message off the moon

#35

Post by dhuk_2018 » Mon, Dec 06, 2021, 7:58 PM UTC

Hams around the world are already bouncing signals off the moon with a lot less power and gain, using modern signal processing techniques.

Re: Bouncing a LoRa message off the moon

#36

Post by blacksmith_tb » Mon, Dec 06, 2021, 8:00 PM UTC

Rebelgecko wrote: post #24

gh02t wrote: post #21

Earlier quoted context omitted.

LoRa isn't really a consumer protocol, more of an industrial one. It's mostly intended for widely distributed sensor networks.

I think Amazon Sidewalk (included w/ every Alexa now) is built on top of LoRa

It looks like they added LoRa to the most recent Ring Bridge[1], but most older Sidewalk devices do their connecting over wifi. Seems likely other new ones will do both.

1: https://fccid.io/2AEUPBHARB001/RF-Exposure-Info/RF-Exposure-...

Re: Bouncing a LoRa message off the moon

#37

Post by vvoid » Mon, Dec 06, 2021, 8:02 PM UTC

Breefield wrote: post #9

detaro wrote: 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?

Background noise - that's one way to put it! The path loss is around 250 dB, so a practical amateur moonbounce station makes use of a very powerful RF amplifier feeding an array of yagi antennas, all mounted on an altitude/azimuth rotator - in other words, it's a radio telescope, and the receiving side hopefully has something similar. You can do a google image search for "moonbounce," the setups are kind of amazing. A lot of investment mostly to exchange morse and specialized low-bandwidth digital modes.

The upshot is that you can communicate with any station that can also see the moon - somebody on the other side of the planet, 12,000km away. Plus there is the unique experience of hearing your own transmission echo, two seconds after you cease.

This kind of setup is well within reach for a commercial enterprise but will never be practical for IoT owing to the laws of physics. On the other hand, there is SNOTEL, a system that bounces snowpack telemetry off of the ionized trails left by meteors...

Re: Bouncing a LoRa message off the moon

#38

Post by intpx » Mon, Dec 06, 2021, 8:03 PM UTC

intpx wrote: post #34

gh02t wrote: post #21

Earlier quoted context omitted.

LoRa isn't really a consumer protocol, more of an industrial one. It's mostly intended for widely distributed sensor networks.

Wasn't it designed for sending sensor data from oil wells spread out over vast swaths of land or something? I've always though of it as shortwave/vhf for packets

Maybe i'm thinking zigbee?

Re: Bouncing a LoRa message off the moon

#39

Post by URSpider94 » Mon, Dec 06, 2021, 8:29 PM UTC

noman-land wrote: post #20

jmole wrote: 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.

Check out https://helium.com - it's a blockchain-based LoRA network, where the blockchain is used to reward uptime and certainty of location of the base stations. Transmissions can be received from 10 miles or more away, if the receiver is located high enough.

Re: Bouncing a LoRa message off the moon

#40

Post by gregwebs » Mon, Dec 06, 2021, 8:49 PM UTC

The YoLink products use LoRa for home automation. I am quite happy using their water leak sensors now. You don't need the quarter mile range, but they communicate with low power successfully in situations where higher frequencies might have reflection issues.