I’d wondered about using moon bouncing in order to distribute video streaming keys (piracy) in a way which would make it impossible to locate the sender. Unlikely to be viable at scale, as the moon isn’t always visible, but it’s an intriguing covert broadcast mechanism.
Open-source communications by bouncing signals off the Moon
51–60 of 88 posts
Re: Open-source communications by bouncing signals off the Moon
#52Earlier quoted context omitted.
> 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.
We've bounced 2.4GHz signals off Venus. Venus.
Re: Open-source communications by bouncing signals off the Moon
#53I started reading thinking it was impossible but it has been done with other devices https://en.wikipedia.org/wiki/Earth%E2%80%93Moon%E2%80%93Ear...
It's been being done for 70 years or so. You just need to be able to generate quite a lot of power on VHF upwards, and have a very low-noise antenna preamp, and a large array of directional aerials to focus the signal.
If you're reasonably handy with simple hand tools you can build a moonbounce array for a couple of thousand and a month or so of evenings.
Re: Open-source communications by bouncing signals off the Moon
#54Earlier quoted context omitted.
Not impossible, just extremely difficult. I'm a ham and getting some contacts over moonbounce is a personal goal of mine. Historically this kind of thing has required some pretty large antenna arrays and very high power though: https://hamradio.engineering/eme-moonbounce-bouncing-signals... http://www.g4ztr.co.uk/app/download/13284489/RaCcom_Feb14+EM... http://www.g4ztr.co.uk/app/download/13300096/Radcom_Mar144+E...
Isn't there a moon bounce mode in WSJT (or one of those digital modes) that provides enough coding gain that 100W and a single large Yagi is enough? I seem to recall hearing something like that... but, yeah, on CW a monster antenna and the legal limit of 1500W seems to be the median system. A long time ago I started collecting parts for a 432MHz EME system. Life got in the way and I never built it out. Good luck with…
> but, yeah, on CW a monster antenna and the legal limit of 1500W seems to be the median system.
A good ten years ago or more, they used Arecibo to transmit CW moonbounce on 70cm. I was able to receive it in my back garden with a handheld and an 11-element Yagi balanced on my clothesline ;-)
Re: Open-source communications by bouncing signals off the Moon
#55KA1GT recently found a $100 “solar cooker” dish on AliExpress. Also available on Amazon. It was tested back in August. Announced on the EME Facebook Group: https://www.facebook.com/share/p/19zLsGZiE7/?mibextid=wwXIfr Output power was 500w
The open.space phased array is a similar power, but an electronically steerable all-digital beamformer.
Was covered on zr: https://www.zeroretries.org/p/zero-retries-0224?#%C2%A7opens... Looks beautiful on a tripod.
Re: Open-source communications by bouncing signals off the Moon
#56I’d wondered about using moon bouncing in order to distribute video streaming keys (piracy) in a way which would make it impossible to locate the sender. Unlikely to be viable at scale, as the moon isn’t always visible, but it’s an intriguing covert broadcast mechanism.
I have no understanding of the physics involved, but could the broadcast location be reverse engineered? (With triangulation and clever math?)
Re: Open-source communications by bouncing signals off the Moon
#5712 V DC (≈1.5 kW peak) How thick is the cable powering this holy amps Batman.
Car starter motors and alternators are on a similar power level.
Definitely. The alternator on a small aviation engine (~100 HP) that I work with is rated for 24V/150A ~= 3.6kW and it’s not really that big in the whole scheme of things. The cables are about the thickness of my thumb.
Re: Open-source communications by bouncing signals off the Moon
#58I’d wondered about using moon bouncing in order to distribute video streaming keys (piracy) in a way which would make it impossible to locate the sender. Unlikely to be viable at scale, as the moon isn’t always visible, but it’s an intriguing covert broadcast mechanism.
I have no understanding of the physics involved, but could the broadcast location be reverse engineered? (With triangulation and clever math?)
Your location is very very visible to any plane or satellite passing overhead.
Re: Open-source communications by bouncing signals off the Moon
#59Earlier quoted context omitted.
> 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.
VHF frequencies, that is.
Re: Open-source communications by bouncing signals off the Moon
#6012 V DC (≈1.5 kW peak) How thick is the cable powering this holy amps Batman.
I’ve wired a 3000W inverter into an RV, and the cables were a bit thicker than my thumbs. Use welding cable, it’s much more flexible.