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mrtnmcc

770 karmajoined 8 tahun yang lalu
Former Principal on SpaceX's Starlink Program. Responsible for modem design on satellites, user terminals, gateways.

Submissions

Seeing Radio Waves at 30fps

crowdsupply.com
3 points·by mrtnmcc·15 hari yang lalu·0 comments

Camera for Radio Waves using 4x4 MIMO

crowdsupply.com
3 points·by mrtnmcc·bulan lalu·0 comments

comments

mrtnmcc
·11 jam yang lalu·discuss
We don't support passive or active radar beyond basic near-field sensing. We also proactively submitted a detailed report to the State Department earlier this year showing we don't exceed any of the USML criteria for ITAR controls. Separately we have an ECCN determination under EAR. This does rule us out from exporting to a few places (Cuba, Iran, Russia, North Korea, Syria, and some regions of Ukraine). But we are able to ship to most countries.
mrtnmcc
·13 jam yang lalu·discuss
Thanks for the support! C-band is really the sweet spot in terms of affordability and compact size (the scale of the antennas and array spacing increases proportional to the wavelength). Maybe at some point we'll develop something at 2.4, but more devices are moving into 5GHz these days.
mrtnmcc
·15 jam yang lalu·discuss
Yes open-space was a short-lived name: https://domainnamewire.com/2026/04/08/u-s-defense-contractor... (good story though) We finally settled on Scale RF for the company and Quad RF for the product (and Moon RF for the bigger phased arrays!). Yes that incident kind of made our brand a mess..
mrtnmcc
·15 jam yang lalu·discuss
Yes-- but it's open sauce!
mrtnmcc
·16 jam yang lalu·discuss
Yes, I actually designed the I/Q calibration for many of Analog Device's transceivers (AD93x), and indeed it is a fun problem. If you're interested in what was done for QuadRF, you can read: https://QuadRF.com/cals/txqec.html (Warning: Math!)
mrtnmcc
·16 jam yang lalu·discuss
We've got the switching noise nailed down. Fortunately the LVDS jitter doesn't affect the sigma delta too badly because that impacts proportional to baseband frequency which is largely filtered out by the decimation filters beyond 40 MHz.. With a total of eight ADCs per QuadRF, you can see we are getting huge savings by being custom! While the per-ADC ENOB is 7-8 bits, another nice thing about phased arrays is that the quantization/ADC noise averages away between elements, so with 8 ADCs in QuadRF we pick up another 1.5 bit giving 8.5-9.5 ENOB, which is frankly better than most SDRs. For the bigger phased arrays that improves further quickly.
mrtnmcc
·16 jam yang lalu·discuss
We should have a video about MoonRF once we finish the QuadRF mass production, look for it ~ early September! Will be legendary! You can read on how the multi-tile synchronization and calibration works here: https://QuadRF.com/docs/#phased-arrays
mrtnmcc
·16 jam yang lalu·discuss
Absolutely :) we're working on documenting an awesome Meshtastic demo. Should have a writeup next week to add to the Crowd Supply updates page. Also Roy on our team will be demoing it (along with the RF augmented reality) at Teardown 2026 in Portland if you're in that neck of the woods.
mrtnmcc
·17 jam yang lalu·discuss
It really depends on the transmitter strength, but if you set the Rx gain high on the QuadRF, we get within 2dB of the thermal noise detection limit.. so about as good as is possible with a receiver this size. I believe a few km is easily doable with a consumer drone but we haven't focused on it.
mrtnmcc
·17 jam yang lalu·discuss
check out https://QuadRF.com/docs/
mrtnmcc
·17 jam yang lalu·discuss
Realtime sound visualization was actually a project I did 20 years ago as a freshman and that (probably?) inspired me to build this AR app in QuadRF.

On balance, I would say this RF version was 200x harder.
mrtnmcc
·18 jam yang lalu·discuss
QuadRF creator here. Happy to answer questions!

We have a quick demo video as well: https://m.youtube.com/watch?v=QvniJk3uNyA

Along with a deeper dive video: https://m.youtube.com/watch?v=zdJ9Tbm8ALg

We didn't give Jeff great direction on camera alignment calibration or setting the radio gain but he seemed to mostly figure it out. We're improving the UI based on his suggestions (it's open source so you can customize it too)

The RF augmented reality is just one of many applications of this brand new 4x4 MIMO software-defined radio built from the ground up. The AR uses a web app to stream RF points that your phone/laptop browser then live-merges with your local camera in the browser. I've been obsessed with low latency and high frame rate to make it a truly AR experience. More technical details at https://QuadRF.com/
mrtnmcc
·13 hari yang lalu·discuss
That's some extreme paranoia. Don't you think the devs are competent or ethical enough to call out an ask like that?
mrtnmcc
·13 hari yang lalu·discuss
What does it even mean to "get updates from China"?

Software these days is distributed and globalized in virtually every sense. Polestar is headquartered in Sweden and much of their software development is in the UK.
mrtnmcc
·20 hari yang lalu·discuss
$499 with Raspberry Pi 5 included.
mrtnmcc
·21 hari yang lalu·discuss
Crowd Supply campaign: https://www.crowdsupply.com/scale-rf/quadrf#
mrtnmcc
·3 bulan yang lalu·discuss
I'm mostly joking.. LNT is always the best policy, even if only (sometimes) for the feeling of pristineness.

Honestly orange peels are incredible, the smell, the robustness. It reminds me of the joke of the plastic cup at Whole Foods filled with orange slices. If only there was a natural packaging alternative...
mrtnmcc
·3 bulan yang lalu·discuss
Suppose this is the article to give that person who chides you for dropping an orange peel on a hike.
mrtnmcc
·3 bulan yang lalu·discuss
Yes the FPGA does digital beamforming and there will be published FPGA pin constraint files so you can write your own Verilog.

For IQ samples, you can stream a continuous 60 MSPS IQ beam over the Ethernet, but for custom beamforming algorithms, the processing needs to be distributed across the FPGAs (for MoonRF it is a SERDES daisy chain, using the same FFC connectors as the links to the RPi-5).

Yes I'll put some newer block diagrams on the website this week. Thanks for the reminder.
mrtnmcc
·3 bulan yang lalu·discuss
That post is truly hilarious though. If everyone talked like that on the nets, the hobby would surely grow a lot faster.