This is brilliant, but on a less than brilliant internet connection like mine the site images are loading at a snails pace. Maybe use WebP rather than png?
An open-source 240-antenna array to bounce signals off the Moon
51–60 of 72 posts
Re: An open-source 240-antenna array to bounce signals off the Moon
#52Pretty cool. And expensive. It's pretty amazing how starlink sells basically this for $200. Pretty sure they subsidize it. Ps you don't really need this. A phased array is great for communicating with or tracking fast moving objects. For something as slow as the moon a simple parabolic dish, either manually aimed or with an az/el motor will be more cost-effective. Motors get expensive too with wind and rain and longe…
Well this is roughly 2 thousand times higher power than a Starlink user terminal. Aand of course it's open source, https://github.com/open-space-sdr/main/
Is starlink that low power? The whole array of this one is 1.5kW. I thought starlink would be at least a few watts especially considering its bandwidth.
Yeah it's impressive and I know hams often spend a lot of money on gear. I don't though (I don't even do HF) but it's certainly cool to see.
But for incidental moon tracking I don't really see the need for a phased array other than the cool factor and the knowledge gained building it. Which are perfectly good reasons to do it of course! Just not technical ones.
Re: An open-source 240-antenna array to bounce signals off the Moon
#53Pretty cool. And expensive. It's pretty amazing how starlink sells basically this for $200. Pretty sure they subsidize it. Ps you don't really need this. A phased array is great for communicating with or tracking fast moving objects. For something as slow as the moon a simple parabolic dish, either manually aimed or with an az/el motor will be more cost-effective. Motors get expensive too with wind and rain and longe…
Well this is roughly 2 thousand times higher power than a Starlink user terminal. Aand of course it's open source, https://github.com/open-space-sdr/main/
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Re: An open-source 240-antenna array to bounce signals off the Moon
#54Every time I hear about Earth-Moon-Earth moonbounce comms, I think of this classic reddit comment: https://www.reddit.com/r/amateurradio/comments/8lpk45/commen...
phased array is better than whatever that guy was doing!
MoonRF mostly takes care of the hardware and pointing, and then the fun is playing with software and signal processing: https://github.com/open-space-sdr/main
Re: An open-source 240-antenna array to bounce signals off the Moon
#55EME has been made a bit more affordable and effective by weak signal modes and DSP.
It used to require very high power, expensive transmission lines, preamps and monstrous arrays of Yagis. Now with JT65x, and SDRs, you can use cheaper coax to get transmit power to the antenna eating that loss with more RF, and put SDRs for RX at the array. People running digital modes are getting away with needing less gain.
5650MHz is the only place to do it with this thing. Might want to break out a calculator before the credit card because path loss has to be more than 285dB. But if you can swing it, might want to buy two so you have someone to talk to. I have not heard anyone using 5650.
Re: An open-source 240-antenna array to bounce signals off the Moon
#56I don't think you should call something 'open source' until you've released the source, but other than that this is an extremely impressive project. HAM's have been doing EME since forever ( https://en.wikipedia.org/wiki/Earth%E2%80%93Moon%E2%80%93Ear... ), it is a very neat trick. It almost looks as if the EME bounce capability of this antenna is a fig leaf or an afterthought, my own 'applications' list would be a l…
It's open source. Here is the GitHub: https://github.com/open-space-sdr/main
That wasn't there when I wrote that comment.
Re: An open-source 240-antenna array to bounce signals off the Moon
#57Re: An open-source 240-antenna array to bounce signals off the Moon
#58Looks interesting, I have many great ideas to test them out with this! I wonder if I can use my SDR with it.
Re: An open-source 240-antenna array to bounce signals off the Moon
#59Earlier quoted context omitted.
> Also, the "can't radar, plz don't ITAR" is horseshit. My assumption is that they're trying to avoid crossing a legal line, as opposed to being personally invested in the idea of preventing radar use by a determined hobbyist.
ITAR feels a lot like Bernstein v. US all over again. Until very recently, everyone who can do anything that would be covered by ITAR was a giant corporation that likes the moat that regulations create, so it's unthinkable to challenge it. But that is changing, just like cryptography was in the early 90s.
RTL-SDR-grade fleet doing passive radar (using radio/TV OTA broadcasts) isn't actually that new; but pretty much any detailed reports have caught self-censoring after TLA visitors came by.
Re: An open-source 240-antenna array to bounce signals off the Moon
#60can amateurs bounce photons off the mirrors left there by Apollo 17 yet or does it still need industrial grade lasers?
Getting industrial grade lasers is the easy part.. it seems to be within range of aliexpress available tattoo removal laser (based on the laser pulse energies listed in https://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment... and rough laser tattoo removal energies listed in https://pmc.ncbi.nlm.nih.gov/articles/PMC10421900/ .. take aliexpress rating with grain of salt)
You do need access to a large telescope (at least 1.2m based on the wiki article), a sensitive detector (is photomultiplier tube sensitive enough??) and most importantly, access to your local laser clearinghouse so you don't accidentally shoot an airplane, blind the pilot and got arrested, or a satellite and start a war (if you believe some guy on quora). Probably the last part is the hardest thing for an amateur