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An open-source 240-antenna array to bounce signals off the Moon

moonrf.com

21–30 of 72 posts

Re: An open-source 240-antenna array to bounce signals off the Moon

#21
post #19

Wild hardware flex for a garage project. Reverse-engineering the Pi 5's MIPI to push 5.6 Gbps from custom MASH sigma-delta ADCs to a Lattice ECP5 FPGA to the Raspberry Pi is serious engineering. The idea that the RF receiver looks like a "camera" to the Pi while the transmitter is a "display" is super creative. Getting a 1.5 kW, 240-antenna EME array for $2,499 is actually cheap for something like this. Their standal…

While true I do worry that it's mandating a pi 5 for each tile? And who knows how specific it is to the 5. Doesn't seem very open relative to something like a usb superspeed, pcie, or 10gbe. USB could be maybe done with the LIFC-33U depending on I/O limitations. PCIe can be done on various FPGAs in the lattice lineup and others. If you use PCIe, theoretically you don't need to reverse engineer how they implemented be…

> While true I do worry that it's mandating a pi 5 for each tile? And who knows how specific it is to the 5.

In the multi-tile array it apparently still only needs one Pi [1] as the FPGAs do the heavy lifting.

[1] https://moonrf.com/updates/

Re: An open-source 240-antenna array to bounce signals off the Moon

#22

"Country restrictions apply". Which countries?

All I guess? If you're licensed you should know what you can and can't do.

No, amateur radio does not cover ITAR.

Which is why I ask. I'm not a lawyer, but there could be a general dual use ban, but with some other regulation that exempts e.g. UK.

Re: An open-source 240-antenna array to bounce signals off the Moon

#23

"Country restrictions apply". Which countries?

Any that forbid or restrict satellite comms? Don’t use this in Iran.

I'm pretty sure the "country restrictions" are about ITAR, not the destination country regulation.

When the page says "uh… do not use this to build a phased array radar… even though you could. And if you do, then in no way were we involved. Just don't", this is extremely likely to be about ITAR.

Re: An open-source 240-antenna array to bounce signals off the Moon

#24

"Country restrictions apply". Which countries?

Each country has different regulations for amateur radio bands. In Germany for example, in the bands > 2 GHz maximum power is capped at 75W PEP [1], the US has vastly different limits [2]

[1] https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html

[2] https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D...

Re: An open-source 240-antenna array to bounce signals off the Moon

#25

"Country restrictions apply". Which countries?

Each country has different regulations for amateur radio bands. In Germany for example, in the bands > 2 GHz maximum power is capped at 75W PEP [1], the US has vastly different limits [2] [1] https://www.gesetze-im-internet.de/afuv_2005/anlage_1.html [2] https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D...

I'm sorry, I thought it was very obvious that I was talking about ITAR export controls, not about destination country domestic regulation.

This is a clue from their webpage: "Not intended for radar applications. Core functionality needed for radar not included due to export control restrictions."

Re: An open-source 240-antenna array to bounce signals off the Moon

#26
post #4

Earlier quoted context omitted.

I'm struggling to understand the signal chain or antenna architecture here. If those two MAX chips are 2829s this would be 2x2 mimo per tile but I'm not super familiar with that product line and the PCB layout looks like a 4x4 setup. And yeah, the agentic stuff is dumb, I've played a ton with doing low level SDR work on Opus 4.6 and it's truly ass. Also, the "can't radar, plz don't ITAR" is horseshit. Some basic fw t…

MAX2850/2851 4x4. Also, large radar stuff is more nuanced than "just some fw tweaks" as you claim. Same as Facebook is not just some PHP scripts...

I used to work radar systems. The point being that the hardware is fully capable. The software side is quite well understood at this point. There will be plenty of repos floating around in a year to turn this into an airborne drone SAR or whatever. Functional range resolution will be around 4m but that's plenty for most shenanigans.

Re: An open-source 240-antenna array to bounce signals off the Moon

#27
post #26

Earlier quoted context omitted.

MAX2850/2851 4x4. Also, large radar stuff is more nuanced than "just some fw tweaks" as you claim. Same as Facebook is not just some PHP scripts...

I used to work radar systems. The point being that the hardware is fully capable. The software side is quite well understood at this point. There will be plenty of repos floating around in a year to turn this into an airborne drone SAR or whatever. Functional range resolution will be around 4m but that's plenty for most shenanigans.

At a functional range resolution of 4M would it even qualify as violating ITAR even if it was tweaked to do so?

Re: An open-source 240-antenna array to bounce signals off the Moon

#28
post #4

Wild hardware flex for a garage project. Reverse-engineering the Pi 5's MIPI to push 5.6 Gbps from custom MASH sigma-delta ADCs to a Lattice ECP5 FPGA to the Raspberry Pi is serious engineering. The idea that the RF receiver looks like a "camera" to the Pi while the transmitter is a "display" is super creative. Getting a 1.5 kW, 240-antenna EME array for $2,499 is actually cheap for something like this. Their standal…

I'm struggling to understand the signal chain or antenna architecture here. If those two MAX chips are 2829s this would be 2x2 mimo per tile but I'm not super familiar with that product line and the PCB layout looks like a 4x4 setup. And yeah, the agentic stuff is dumb, I've played a ton with doing low level SDR work on Opus 4.6 and it's truly ass. Also, the "can't radar, plz don't ITAR" is horseshit. Some basic fw t…

> 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.

Re: An open-source 240-antenna array to bounce signals off the Moon

#30

> Power Supply: 12 V DC (≈1.5 kW peak) That's a lot of juice for 12VDC

>> Power Supply: 12 V DC (≈1.5 kW peak)

> That's a lot of juice for 12VDC

Indeed it is. It's 125 amps, which apart from car starting motors is essentially unheard of because of wiring losses. I think the article somehow got this wrong.

At these power levels, rational designs raise the source voltage, then down-convert closer to the loads.

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