HN user

mrtnmcc

805 karma

Founder of Scale RF Inc. Former Principal on SpaceX's Starlink Program. Responsible for modem design on satellites, user terminals, gateways.

Posts5
Comments254
View on HN

Yes once you have runtime IQ compensation figured out in digital, its essentially free and easily puts your image rejection ratio into the -50 to -60dBc range. I don't have a write up on the RxQEC, but it's rather trivial: you periodically compute the 2x2 IQ correlation matrix, then take the sqrt (e.g., Cholesky) and multiply your incoming Rx samples by that inverse. You can extend that further for widerband by using FIR taps but here the baseband matching is good enough to go with "single tap"

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.

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.

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.

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.

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.

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/

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.

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.