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/
The really intriguing part is the "Custom ADC" here, seems like some kind of 1-bit ΣΔ oversampling ADC (704 MSPS?). Single differential transistor, and captured by FPGAs LVDS RX.
Neat way to reduce cost and pin-count? But I think the typical FPGA clock tree has poor jitter performance. Not using the internal PLL(s) might help with spurs but the clock buffers are unavoidable.
The documentation mentions it's likely further degraded by noise from switching regulators. Oh the joys of hunting RF noise sources.
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.
But this is a really interesting use case as well, and something that could be used for a 16 channel logic analyzer with analog recording support like the Saleae Logic 16 Pro, but without expensive ADC from Analog Devices.
Yeah, jitter doesn't matter too much at low frequency IF. I/Q calibration is more likely to be the bottleneck. That and close-in spurs from the fractional PLLs.
I have very little experience with MIMO / phased-arrays, this application likely doesn't need ultra high SFDR.
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!)
Oh wow, the AD936x series was impressive for its I/Q calibration. Still is I guess, because there's been no compelling alternative even a decade later.
As I mostly deal with single channel applications, I get to use double superhet and avoid runtime calibration. Not an option here, Zero-IF has too much in the Pros column for multichannel.
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"
I like to think of myself as pretty well-versed when it comes to hardware and software and even some RF. But this conversation has me hitting search a lot, lol. It's fascinating reading experts talk about a domain I have less experience in.
Heh, welcome to RF; there are more rabbit holes to go down in domain specialty than I think there are grains of sand on a beach. I've gone down like... two. And I'm pretty overwhelmed.
I think that's why a lot of EEs and developers wind up getting an amateur radio license, or at least running a few fun RF projects.
Glad I’m not the only one. I’ve been tinkering with sensors, robotics, sdr and similar stuff for 20 years now, but this conversation was way over my head.
For those confused about what this means, my understanding is this: when quantizing a wave you can use sampling rate to derive missing bits, so using even one bit can work if you do it fast enough, but jitter is a problem because it means the clock doesn't cleanly sync and it doesn't help non-quantization noise like those generated from switching supplies. Corrections welcome.
Are you concerned about the issue that KrakenRF ran into with their passive radar demo project violating ITAR rules, or is that something that can easily be avoided by just not doing that specific kind of application?
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.
The occupied ones, presumably.
But why is Ukraine broken up? Surely, you will be dealing with a government, and they'll know what to do/ where there current borders are.
Product looks cool, not sure what I’ll use it for but did just purchase it on crowdsupply :)
How did you settle on that frequency range btw? It’s 4.9 - 6ghz, so it will visualize the higher freq WiFi, but I guess it will not work for the 2.4ghz WiFi, or Bluetooth which is also around that frequency? And I don’t know tooo much about RF, but would including support for that range also, have necessitated much more complex/expensive hardware/antennas ?
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.
My feel would be that 2.4 has the advantage of being much longer range and there are plenty of sources for 2.4 - if you wanted to look at back-scatter and not just sources of emission. The primary demo of this piece of equipment is looking at radiation sources, but as you guys show there are plenty of other possible applications. I feel like since 2.4Ghz stuff has been around for ages.. the stuff should be much cheaper? Just a guess though :) Would be curious to know what the reality looks like
And cool to see you guys are from Santa Barbara. Lots of relevant talent there :)
This does look cool - but I suspect most of the stuff I'd use it with is 2.4 Ghz (i.e. ISM band) - IOT devices, wireless keyboard/mouse, wireless cameras, drones etc
Is a 2.4Ghz version mostly about the larger physical size? Or are there other technical limitations to overcome as well?
And cost wise - would it be 2x this version ($499) - or higher?
Super cool project I've been following for a while. Are you pivoting away from Earth-Moon-Earth radio astronomy? I first bookmarked this project when your site was hosted at https://open.space
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..
Super cool! I noticed you had a blurb about it being used for mesh networks? Could you please go into more details/provide links to resources to learn more about that?
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.
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
I assume it depends mostly on what frequency and TX power the drone in question is using, as well as the RF environment you're operating in and the noise floor of the SDR
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.
Funny, in the "imagine what governments are capable of" vein, I just read this[0] a few minutes ago before coming over to HN to find this post trending.
Yep, been in the works for a while. Ericsson, Nokia Bell Labs and Qualcomm have been publishing press releases regarding ISAC and telecom providers also sees new potential market of S2aaS, especially if there is a push towards autonomous robots, vehicles that need the data for mapping & training data.
Future networks using millimeter-wave (mmWave) and sub-terahertz (THz) frequencies may collect or infer detailed information about people, devices, bystanders, passive objects, and environments in a sixth-generation (6G) deployment area. It may detect breathing and heart rate of biological bodies.
Remember how for years starting in the late teens and fizzling out over covid university paper after university paper about "this is so cool look how we can see through walls by essentially using 5g and wifi as ambient light" and they steadily marched up the chain from simple room layouts to furniture layouts, occupant detection, occupant movement and then started being dressed up with the usual dogwhistle language about "emergency services" that people who are building tech to help infantry/police entry teams use to make it seem more noble and then after that it all just kinda stopped being publicized with any sort of regularity?
I'm not a conspiracy theorist but I'd say all the people working on that shit got hired.
One day I want to build something like this, except for sound. It would be great to get a heading and distance for where a sound is coming from.
This could be both for small scale things (e.g. which part of this is squeaking?) or large scale (e.g. is that booming noise coming from the construction a few blocks away?)
There are a few knockoff options too, which are not quite as nicely calibrated, but get the job done for much less than Fluke-level prices. Like the FOTRIC TD2.
These are the kinds of things you look at and think - maybe I DO need night-vision, or a soldering iron with a cpu, or a thermal imager, or a steerable endoscope or now an acoustic imager....
+1 to thermal imager. I use mine to locate hot wires, heating and cooling gaps in the roof and around windows, car maintenance, the pizza oven, and its even sensitive enough to ‘see’ studs in the wall.
Priceless on one occasion for finding leaks in the ceiling, which are notoriously hard to pinpoint.
Can also be used for looking at heat leaking into or out of your house via conduction, which can help you determine where there might be more insulation needed, or maybe a particular wall needs more shade in summer.
Has anyone tried acoustic imaging for water leaks inside walls? I live in a multi-floor 1900s Victorian. A leak can affect several units, and tracing the source can mean opening walls or floors in multiple places, and coordinating access has been getting harder with less WFH.
Could one of these tools help map water pipe routes and trace a leak, or are they only going to be useful for air and gas leaks?
Initially I scoffed, but then I recalled that certain RF bands are disproportionately absorbed by water and this is used for certain sorts of atmospheric imaging by satellites. So you'd need a moisture "light" and an RF camera. Other than being cost prohibitive it sounds like an awesome toy.
It still works pretty well in the IR band. I know that one from experience due to storm damage to our roof ;-)
A leak only turns invisible if the water has the exact same temperature as the wall and there is no meaningful evaporation happening (as that cools the affected area).
Of course don't let me stop you from actively probing your all using RF. Though also there you might have good chances with IR, since wet $stuff should behave differently than dry $stuff ;-)
There is a man call leak detective, who hunts for leaks in the UK. one tool he has is shutting off the water and filling the pipes with gas and using either sound or gas detector to pin down leaks.
Up until the 90’s airline in flight entertainment use stethoscope style earphones. My dad used to steal them for his workshop as a way to hear for leaks in various parts.
Our ears and eyes are very high bandwidth sensors.
Not sure if you've heard of them, but they're starting to come to market with this exact thing aside from distance detection and more on the "which part is squeaking" side.
The army has one of these for sniper triangulation, and Boeing made a civilian version for optimizing sound dampening on the 787. I don’t know if they kept doing that on subsequent planes but I would expect so given how enthusiastic they were about being able to apply the weight budget to greater effect.
You need really high clock rate sensing to differentiate the arrival time for sound from microphone arrays where they are all less than a nanosecond separated from each other.
A nanosecond? The speed of sound at sea level in dry air is approximately 330m/s. So at say 3.3 kHz, the rough logarithmic middle of the audible spectrum, K=2π/lambda is 2π/0.1 m=20 π rad/m. A phase difference from a source difference k. ∆r would therefore likely be far more easily resolved than that for many physical ∆rs then, no?
Sensors around 12.5 inches apart will be a millisecond separated. The actual device was from a fuzzy recollection of a picture I saw, was probably 700 microseconds across. But it was a sphere with many sensor so adjacent sensors were less than .1 ms of separation. They would have all the time in the world to calibrate such a thing.
My guess is rather than triangulation, they probably just find the two microphones with the widest phase separarion between their signals and draw a line back between them. I don’t actually know how much 3D sonic math they’re doing.
What I do recall is that it was tech that had recently reached the Cheap Enough to Use status at the time, which is about 20 years ago now?
Making the hardware is fairly achievable without having to do fancy things. but if you want >8 channels you'll need to make some custom interface hardware.
> It sounds like they had to reverse-engineer the MIPI protocol used on the Pi 5 to do this (since it goes through the RP1 chip), and the way it's architected, you can daisy-chain multiple QuadRF modules together, letting each module calculate it's own phase shift.
How are they planning on distributing a shared, highly precise clock for that purpose? That's already a PITA if you do QO-100 modes that need high precision, but usually there it's enough to have one good clock that you feed to the LNA... but here? Every single one of these modules needs a very precisely identical timing signal and the kind of chips you can use to multiplex a reference clock signal are pretty expensive.
So, essentially, the secret sauce is tracing a known calibration source's movement to compensate for different cable lengths or weird physical tile arrangements? Neat!
Whos paying the telcos for those 5G connections and also has the FCC been degraded so much that they would allow for undeclared radios in consumer products?
But in your scenario they are an integral and necessary part of the device, so it's costed in.
In a television it's an added cost and it's unclear if serving ads really can offset that extra $25-100 of hardware (and included data) you ship on a $200-1000 television.
It's also unclear to me if the low data packages they come with would be enough to serve meaningful ads to begin with. Those devices usually come with a fixed plan of 100MB/month for 5yrs (or along those lines). Modern smart tv ads are very often video or at least hi res images.
> In a television it's an added cost and it's unclear if serving ads really can offset that extra $25-100 of hardware (and included data) you ship on a $200-1000 television.
Amazon seems to have done the math and found that it makes sense to give a $20 discount on a $180 device if it lets them display very unobtrusive ads on the lockscreen. So I don't think you are correct.
Why are you assuming the primary motivator is to serve ads? Smart TVs were already caught running content ID against the contents of the screen and phoning that data home. "Routing at the edge" is the euphemism for the logical extension of that.
> extra $25-100
Your estimated costs are off by at least one order of magnitude, probably two.
Of course none of this makes much sense in a world where smart TVs have ubiquitous wifi, most consumers have one, most consumers run the stock OS, and most consumers connect it to the public internet. It would be entirely viable if not for that status quo.
Unfortunately, it's used to spy on you, and insurance companies are known to buy the data to profile customers or prospective customers. The good thing about Fords is that the cell modem often has its own fuse.
Secret 5G is not as common because there is a huge incentive to resell the free service. Maybe with eSIM it will be harder. Kindles uses to have a free data plan SIM.
Not all mobile data APNs go to the Internet. You can't resell an IP service that lands on an RFC1918 network with exactly one IP:port available; the API endpoint.
Not saying I've seen this in devices, but I have built and run mobile data networks with private APNs.
No. I did see in the 5G design that that type of thing was a consideration. It may well be that phone companies aren't selling like that, however it certainly would make sense that they would be looking for companies who want a deal. Most of the cost of service is fixed, and a large number of customers want service during particular peak times and so they can serve that peak data even at off peak times such as when everyone's asleep and so if they could sell that time only that is a little bit more money. It only makes sense if those buying off peak times do have other alternatives that they would turn to instead.
The FCC is literally powerless nowadays for all intents and purposes. They've abrogated so much of their authority to the states now that they might as well be eliminated. What little authority that remains with it is bought and paid for to the point that I'm sure you could get anything "approved" if you wanted.
> has the FCC been degraded so much that they would allow for undeclared radios in consumer products?
Well... most TVs already have a WiFi/BT chipset for stuff like advertisements or, especially with Apple, high-bandwidth video streaming. There is already a radio module present, but (IIRC) you don't have to disclose what exactly that module is capable of.
It always impresses me that technology ideas once exposed in the nefarious background of the Snowden revelations, has now become mainstream, almost passé among the technocratie, but then I remember that there is a very dominant event horizon where all technology is weaponized/de-weaponized according to the intentions of its users..
It's going to been pretty wild to see QuadRF being applied for things. I can only imagine there are weapons-technologists who will bolt this onto hunter/killer drones at some point. A lynchpin technology for the inevitable drone wars.
> I have heard claims of devices (mostly TVs) supposedly coming with secret 5G cell uplinks built
This is occasionally mentioned on HN, but I have not yet seen a specific instance of this. Please share if you know something about secret 5G cell modems used to spy on people.
It also appears to have a fairly narrow detection angle. This might work for spotting a drone when you already know roughly where it is, but that problem becomes infinitely harder when you have to scan the entire sky.
RF drone detection has been a challenging problem for quite a while. Lots of solid state radar/RF detection products have emerged in the space, but it is not a trivial problem. And that is for drones with active RF comms, anything flying autonomously is even harder to detect at a far enough range to actually do something about.
> RF drone detection has been a challenging problem for quite a while.
Correct, there is no bullet proof cuas system to this date.
> anything flying autonomously is even harder to detect
Not just autonomously, because even in autonomous mode you would still need other RF like gnss, but you can fly drones without any rf signature at all and utilize a pre captured images saved on board to navigate the drone accurately using its cameras (normal or thermal). In this case, rf interference won’t work, it won’t be detected based on rf signature either, you will have to rely solely on visuals and acoustic, fly at night, and only left with acoustics.. it is a very hard task from technical standpoint.
Not tracking, jamming. A drone that has no rf dependencies as I mentioned above plus its small footprint is unstoppable, the only current limitations in drones is the endurance.
I just kinda skimmed through it, so it detects drones in sky? Am I understanding this correctly? That might have some defense application considering what's going on in Eastern Europe right now.
It detects drones which send out RF signals at the same frequency band. Most drones used in Ukraine are tethered with thin optical wire exactly because one of the first anti-drone measures was to simply jam them at the frequencies the operators used.
There are some more advanced anti-drone measures at work: Like blasting them with directed high-energy microwaves to destroy the circuits.
Most drones aren't optical because optical drones sacrifice payload and distance, they're only used when broad spectrum jamming is expected. Jamming of that type is expensive and heavy enough that infantry probably won't be jamming, or light vehicles, or a lot of infrastructure.
Brute force wide band jamming would be easy too and would make hopping ineffective. Unless drones use self tuning antennas to overcome losses, they can't hop too far away from the antenna resonance frequency, which makes jammers job easier.
How come? It plainly negates the "easy" part. It's not easy at all, you need to scale your signal path to the magnitude of power. I.e. the expensive part.
So what? It's not the airborne platform with limited energy and an explosive payload that needs to do the jamming, it's the ground-based targets.
However, as pointed out elsewhere in the thread a lot of these jamming arguments are academic because drones are either tethered with a fiberoptic cable and/or navigating autonomously.
True, but they can't use directional antennas nor lots of power, and once they're far enough from the transmitter inverse square law does the rest. Ground stations always have an advantage because of higher gain antennas and more power available.
FPV drones in the Russian war are generally pretty dumb devices, there's usually no frequency hopping involved to begin with. They have a lot more in common with baby monitors than with modern military comms.
> That might have some defense application considering what's going on in Eastern Europe right now.
This is a bog-standard phased-array RDF calibrated for WiFi freqs; that stuff is already in every single defense show.
Also, that's why there's jamming everywhere (to blind that kind of things) and why many UAVs are now tethered to optical fibers instead of being RF-controlled.
Why would they put phased arrays on UAVs? They are typically using beam-forming antennas + cheap gimbals for the same purpose.
Phased arrays are nice when you want to scan a large angular surface very fast; when it comes down to optimizing RF radiation toward your ground station, a gimbal is cheaper, simpler, and works fine.
Really depends; there you can see both Lockmart exhibiting multi-billions project, and 150m after some Serbian company selling jet engines for UAVs for a couple hundreds.
I had a friend who'd just gotten out of EE school as a non-traditional student who was working for a company that was making radars for tracking drones maybe five years before the 2022 Russian invasion.
That was an active system, similar in concept to the radars used in air defense system just scaled down and faster acting.
The one in this article is a passive system that sees the transmitter on the drone. The comm link is the obvious weak spot on the drone as it can be detected and jammed, it is fairly inevitable that lethal attack drones that work anonymously will be widespread as a result.
According to CivDiv's channel about 70% of the drones used are still RC FPV drones. They are cheaper longer range and have a slightly simpler supply chain. Fiber optic cable prices have exploded because of the war.
How about "non-professionals"? It could be useful to check device before sending for pre-compliance / compliance checks and save money - that would avoid very expensive iterations.
But there are already benchtop or handheld signal analyzer for that purpose.
This seems more like a tool for checking across entire large assemblies like an entire building, car, aircraft, etc, for unknown sources. If you have an individual discrete device that you're already testing, just using traditional instrumentation seems reasonable, but on a large, complex assembly, I can see it being useful. Also useful for things like detecting if a particular antenna is working without actually going up there to measure near it; if you have a MIMO setup with multiple antennas, this might make it easier to check if all of them are working correctly when mounted in inconvenient areas.
I think that for a single device, this probably wouldn't help much over just having a more traditional signal analyzer, either benchtop or handheld. If you know what you're testing, just using a signal analyzer around it will give you a good first pass picture of emissions, and probably be much more informative and precise than this.
This seems more useful for finding unknown or hidden RF sources, for instance looking thorugh an entire building to find unknown RF sources, or maybe a whole complex assembly like a car or aircraft.
I don't think it's any good for that. It's relatively narrowband and not the frequency you usually have issues with EMC on (5 to 6GHz - unless you are specially transmitting on this frequency you are unlikely to emit anything there).
I don't think it was ever (past 30 years) particularly secret? The general concept is long (100+ years) established. However pulling it off used to be exorbitantly expensive.
I don't understand what this is trying to say. Everyone who has ever used wi-fi knows that it works through walls. You try to connect to a wi-fi in an apartment, and there are dozens of other networks showing up.
I'm guessing if you can "see" Wifi through a wall, you can also infer some things about what's behind the wall, because the signal will have certain obstruction patterns. It becomes an xray.
Would something like this work at much lower frequencies? Being able to see RF at 3-30MHz would be fantastic for hunting RFI in the amateur radio HF bands.
Neat! SDRs have been available at reasonable price points for some time but the processing power to engage with wifi and other digital signals has been somewhat elusive. Assuming RAM can be purchased in the future, I think we might see a lot more prosumer-targeted devices for doing raw signal analysis in the future.
Do you have specific SDR in mind? I thought the v2 dongle doesnt have the range of Wifi? SDR is something Ive just recently want to learn to help me understand electromagnetism
I thought that might just be Amazon resellers capitalizing on marks being too lazy to go off site at first when they were $280 at Microcenter (still crazy expensive). [0] Then Adafruit had them for the same $350! [1] And it really does seem to be driven by the ram too the 4 GB model is only $130 (or $104 at MC).
Just like eBay, an Amazon listing for a certain price does not mean the item is actually /selling/ for that price -- especially with badly-coded dynamic re-pricing algorithms hooked into listings these days.
It's not completely out of line with other RPi sources listed on the RPi Foundation's own site. It's the same price as Adafruit for example but about $50 more than Mirco Center (though that is for instore pickup only so only for people lucky enough to live close to one).
With the end of easily available rtl-sdr dongles it's a relief to see someone has wrung such exceptional RF instantaneous bandwidth out of an RPI alternative interface. I really hope use of the camera interface for RF takes off.
Yeah, Kraken SDR removed some functionality due to these concerns, if I remember correctly.
Odd, because export controls don't generally apply to published material (like open source software), but maybe they were worried that because they were also selling the hardware they could have issues due to the combo being export controlled.
As someone who works daily with export-control-adjacent hardware and software, my experience is that people tend to aggressively self-censor to a far higher standard than export control regulations actually require. The perceived headache of drawing the ire of whoever it is the enforces this stuff (which as I type this comment I'm just realizing I don't know who specifically is responsible for that) is so scary that people don't want to take any risk at all of being targeted.
> Direction finding equipment for determining bearings to specific electromagnetic sources or terrain characteristics specially designed for defense articles in paragraph (a)(1) of USML Category IV or paragraphs (a)(5), (a)(6), or (a)
ITAR part 121.
The "specifically designed for defense" probably makes this OK, but IANAL.
The covered materials are very broad, though often limited to equipment built "for purposes of", like in this section.
Title 22 Chapter I Subchapter M Part 121 - The United States Munitions List - Category XI Paragraph b
Electronic systems, equipment or software, not elsewhere enumerated in this subchapter, specially designed for intelligence purposes that collect, survey, monitor, or exploit, or analyze and produce information from, the electromagnetic spectrum (regardless of transmission medium), or for counteracting such activities.
At what point does a microphone become an intelligence device, when we have so many types of microphones. Is it an arbitrary label I can add or remove to a product? Will it apply equally to large manufacturers?
Where did your quote come from? The comment you're replying to says "specially designed for intelligence purposes". The word "specifically" doesn't appear.
> If the open source community can come up with something like this, just imagine what governments are capable of.
Since ~2022 and accelerated by the Russian aggression against Ukraine, governments are now behind both private and open source for frontier technology.
The companies that captured government contracts in the last century can’t move fast enough to bring tech into the government and national technology policy and funding is collapsing compared to the private sector
This has me thinking that fiber optic drones using this technology might be able to discover the location of signal-jamming equipment. But only for the good guys.
if it can spot/track drones that is a marketing opportunity for airports around the world that have to deal with drone nonsense which shut down flights for days
Most major airports will already have a counter-UAS system, it's a huge industry.
One big issue with radar is that it has the same problem pilots and human observers do: it struggles to distinguish drones from anything else in the sky (birds, balloons, planes, etc.). This is an active and improving research space, but by and large with radar, when your pilots report a drone, you still don't know how to figure out if it's the typical mis-identification or something real.
* Pilots are very concerned about life and safety and are heavily exposed to drone “incident” related anecdotes, so they err far on the side of caution with drone sightings. Which is to say a very low percentage of them are real.
* Poorly implemented cUAS systems, especially ones based on passive or active RF locating (radar) can actually make the problem worse: they hallucinate everything into drones, pilots hallucinate everything into drones, and now everything is a drone. This also happens frequently when people try to repurpose military systems (which are usually designed to operate in significantly less crowded environments and trigger at the slightest hint of an issue, due to mostly orthogonal-to-airports threat models people discuss at length on this thread like “dark drones”) into urban use.
This type of array based directionfinding system is cool and it could work as a small ingredient in a drone detection system, but it’s not anywhere near the state of the art in the space and most airports are probably already ahead of this to some extent.
If would likely need to track them well (not sure from this article/video if that's the case?) to be useful in that scenario...
Drawing a splodge in roughly the location (not sure if there's range info either? I doubt it if it's passive) overlaid on the video likely won't cut it...
There are more way advanced systems for cuas, where they infuse radar and visual and acoustic plus now AI to minimize the false positives, but practically speaking, they are not bullet proof and still fail. RID (remote ID) is a way to have a cooperative communication and was mandated in US, but there are ways too to spoof it and cloak it.
Yeah RemoteID is trivial to spoof using an ESP32. Most hobby pilots I know simply don't comply with RemoteID. And bad actors certainly won't purchase a $75 device to add to their drone.
It does become a bit more difficult with consumer grade off the shelf drones because it's built in. Still defeatable by the determined of course.
Passive radar is fine for gigantic airliners with all regard for efficiency, none for radar cross section, and that fly above most obstacles. For drones you might be trying to scratch signal not only from below noise floor, but at the edges of quantization.
I want this. I have Wifi door lock too far away from base station. It was often stuck in a loop trying to connect to neighbours' Wifis. By try and error I managed to block those using metal foil, but it was hard work.
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/
The really intriguing part is the "Custom ADC" here, seems like some kind of 1-bit ΣΔ oversampling ADC (704 MSPS?). Single differential transistor, and captured by FPGAs LVDS RX.
Neat way to reduce cost and pin-count? But I think the typical FPGA clock tree has poor jitter performance. Not using the internal PLL(s) might help with spurs but the clock buffers are unavoidable.
The documentation mentions it's likely further degraded by noise from switching regulators. Oh the joys of hunting RF noise sources.
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.
That’s so cool!
Reading these comments first, I assumed you were using a variant of Spartan 6 LVDS TDC trick which allows up to 200 Msps rates. (https://sps.ewi.tudelft.nl/pubs/Homulle15fpga.pdf)
But this is a really interesting use case as well, and something that could be used for a 16 channel logic analyzer with analog recording support like the Saleae Logic 16 Pro, but without expensive ADC from Analog Devices.
Yeah, jitter doesn't matter too much at low frequency IF. I/Q calibration is more likely to be the bottleneck. That and close-in spurs from the fractional PLLs.
I have very little experience with MIMO / phased-arrays, this application likely doesn't need ultra high SFDR.
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!)
Oh wow, the AD936x series was impressive for its I/Q calibration. Still is I guess, because there's been no compelling alternative even a decade later.
As I mostly deal with single channel applications, I get to use double superhet and avoid runtime calibration. Not an option here, Zero-IF has too much in the Pros column for multichannel.
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"
I like to think of myself as pretty well-versed when it comes to hardware and software and even some RF. But this conversation has me hitting search a lot, lol. It's fascinating reading experts talk about a domain I have less experience in.
Heh, welcome to RF; there are more rabbit holes to go down in domain specialty than I think there are grains of sand on a beach. I've gone down like... two. And I'm pretty overwhelmed.
I think that's why a lot of EEs and developers wind up getting an amateur radio license, or at least running a few fun RF projects.
Glad I’m not the only one. I’ve been tinkering with sensors, robotics, sdr and similar stuff for 20 years now, but this conversation was way over my head.
For those confused about what this means, my understanding is this: when quantizing a wave you can use sampling rate to derive missing bits, so using even one bit can work if you do it fast enough, but jitter is a problem because it means the clock doesn't cleanly sync and it doesn't help non-quantization noise like those generated from switching supplies. Corrections welcome.
Are you concerned about the issue that KrakenRF ran into with their passive radar demo project violating ITAR rules, or is that something that can easily be avoided by just not doing that specific kind of application?
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.
> does rule out..... some regions of Ukraine
The occupied ones, presumably. But why is Ukraine broken up? Surely, you will be dealing with a government, and they'll know what to do/ where there current borders are.
Why would they be dealing with government and not some hobbyist on the wrong side of the border?
Product looks cool, not sure what I’ll use it for but did just purchase it on crowdsupply :) How did you settle on that frequency range btw? It’s 4.9 - 6ghz, so it will visualize the higher freq WiFi, but I guess it will not work for the 2.4ghz WiFi, or Bluetooth which is also around that frequency? And I don’t know tooo much about RF, but would including support for that range also, have necessitated much more complex/expensive hardware/antennas ?
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.
Is there a decent rule of thumb about how this style of antenna scales with frequency?
I'd kinda like something like this that could do 2.4GHz, 850-950MHz and even down as low as 400MHz.
Would by uneducated guess that 2.4GHz antennas would be twice the size, 900MHz about 6 times the size, and 400MHz about 10 times the size?
My feel would be that 2.4 has the advantage of being much longer range and there are plenty of sources for 2.4 - if you wanted to look at back-scatter and not just sources of emission. The primary demo of this piece of equipment is looking at radiation sources, but as you guys show there are plenty of other possible applications. I feel like since 2.4Ghz stuff has been around for ages.. the stuff should be much cheaper? Just a guess though :) Would be curious to know what the reality looks like
And cool to see you guys are from Santa Barbara. Lots of relevant talent there :)
If you ever want to go into the KHz range, you could build a ship-scale platform to carry the antennas :D
This does look cool - but I suspect most of the stuff I'd use it with is 2.4 Ghz (i.e. ISM band) - IOT devices, wireless keyboard/mouse, wireless cameras, drones etc
Is a 2.4Ghz version mostly about the larger physical size? Or are there other technical limitations to overcome as well?
And cost wise - would it be 2x this version ($499) - or higher?
Is the RTL for the FPGA available to be tinkered with?
Super cool project I've been following for a while. Are you pivoting away from Earth-Moon-Earth radio astronomy? I first bookmarked this project when your site was hosted at https://open.space
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..
Super cool! I noticed you had a blurb about it being used for mesh networks? Could you please go into more details/provide links to resources to learn more about that?
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.
That is super cool, man.
Do you have a demo for that 240 elements assembly?
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
Nice project, congrats!
Rx/TX isolation?
Typical image rejection (dB)?
Does it support hardware level timestamping to align tx and rx samples through soapy?
Really cool! Just ordered one. Do you guys have an active lab in SB?
What distance of drone detection would this theoretically have?
I assume it depends mostly on what frequency and TX power the drone in question is using, as well as the RF environment you're operating in and the noise floor of the SDR
Cool project! What is the max detection range?
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.
if I put two of these far-ish apart, can I get better 3d/4d data?
of course? not working directly together maybe, but put them at right angles and you get depth without relying on signal amplitude analysis.
did I misunderstand the question?
Something like this: https://youtu.be/YZkLQsv3huo
can this sense mice?
Funny, in the "imagine what governments are capable of" vein, I just read this[0] a few minutes ago before coming over to HN to find this post trending.
[0] https://www.prnewswire.com/news-releases/the-future-takes-fl...
Yep, been in the works for a while. Ericsson, Nokia Bell Labs and Qualcomm have been publishing press releases regarding ISAC and telecom providers also sees new potential market of S2aaS, especially if there is a push towards autonomous robots, vehicles that need the data for mapping & training data.
Future networks using millimeter-wave (mmWave) and sub-terahertz (THz) frequencies may collect or infer detailed information about people, devices, bystanders, passive objects, and environments in a sixth-generation (6G) deployment area. It may detect breathing and heart rate of biological bodies.
https://eprint.iacr.org/2026/1069
Seems like a contender for the tricorder prize that was announced ten or so years ago might not be too far off.
I have a feeling they are not planning to sell it to government agencies for $500. Our tax dollars will go a lot less far I expect.
Remember how for years starting in the late teens and fizzling out over covid university paper after university paper about "this is so cool look how we can see through walls by essentially using 5g and wifi as ambient light" and they steadily marched up the chain from simple room layouts to furniture layouts, occupant detection, occupant movement and then started being dressed up with the usual dogwhistle language about "emergency services" that people who are building tech to help infantry/police entry teams use to make it seem more noble and then after that it all just kinda stopped being publicized with any sort of regularity?
I'm not a conspiracy theorist but I'd say all the people working on that shit got hired.
Sorry not sorry for the run on sentence.
I stopped reading halfway through in frustration and then saw your apology.
You only need to apologise to yourself really.
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One day I want to build something like this, except for sound. It would be great to get a heading and distance for where a sound is coming from.
This could be both for small scale things (e.g. which part of this is squeaking?) or large scale (e.g. is that booming noise coming from the construction a few blocks away?)
Fluke has made an acoustic imager for a while now. It is used for detecting leaks:
https://www.fluke.com/en-us/product/industrial-imaging/fluke...
There are a few knockoff options too, which are not quite as nicely calibrated, but get the job done for much less than Fluke-level prices. Like the FOTRIC TD2.
I think a few people have made homebrew versions too, like this one mentioned on HN: https://news.ycombinator.com/item?id=45137584
interesting on amazon:
fluke $25k
flir $10k
td2 $1k
These are the kinds of things you look at and think - maybe I DO need night-vision, or a soldering iron with a cpu, or a thermal imager, or a steerable endoscope or now an acoustic imager....
If you own your home I'd say you need a thermal imager. Just the ability to diagnose clogged pipes is priceless.
https://x.com/ThermoInstagram/status/909356506059026432
Also for checking if microwaved food is ready.
+1 to thermal imager. I use mine to locate hot wires, heating and cooling gaps in the roof and around windows, car maintenance, the pizza oven, and its even sensitive enough to ‘see’ studs in the wall.
Priceless on one occasion for finding leaks in the ceiling, which are notoriously hard to pinpoint.
> and its even sensitive enough to ‘see’ studs in the wall.
oooh my. My studfinder is always a little uncertain. I would love a second opinion.
Can also be used for looking at heat leaking into or out of your house via conduction, which can help you determine where there might be more insulation needed, or maybe a particular wall needs more shade in summer.
Has anyone tried acoustic imaging for water leaks inside walls? I live in a multi-floor 1900s Victorian. A leak can affect several units, and tracing the source can mean opening walls or floors in multiple places, and coordinating access has been getting harder with less WFH.
Could one of these tools help map water pipe routes and trace a leak, or are they only going to be useful for air and gas leaks?
For a water leak a sound imaging device is not going to help you.
You should definitely try a thermal camera. Any moisture will create small temperature differences which are easily picked up by a thermal camera.
Flir has some thermal cameras with 'special moisture' modes. In the end, wet areas are just colder.
Moisture camera. Now there is an idea.
Initially I scoffed, but then I recalled that certain RF bands are disproportionately absorbed by water and this is used for certain sorts of atmospheric imaging by satellites. So you'd need a moisture "light" and an RF camera. Other than being cost prohibitive it sounds like an awesome toy.
It still works pretty well in the IR band. I know that one from experience due to storm damage to our roof ;-)
A leak only turns invisible if the water has the exact same temperature as the wall and there is no meaningful evaporation happening (as that cools the affected area).
Of course don't let me stop you from actively probing your all using RF. Though also there you might have good chances with IR, since wet $stuff should behave differently than dry $stuff ;-)
WArning I am not an expert
There is a man call leak detective, who hunts for leaks in the UK. one tool he has is shutting off the water and filling the pipes with gas and using either sound or gas detector to pin down leaks.
A lot of the time he just listens though.
Up until the 90’s airline in flight entertainment use stethoscope style earphones. My dad used to steal them for his workshop as a way to hear for leaks in various parts.
Our ears and eyes are very high bandwidth sensors.
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.
Not sure if you've heard of them, but they're starting to come to market with this exact thing aside from distance detection and more on the "which part is squeaking" side.
https://www.youtube.com/watch?v=l8-5lSVCR2w
I think you'll be very interested in this awesome project
https://ribbonfarm.com/2016/06/29/the-daredevil-camera/
The army has one of these for sniper triangulation, and Boeing made a civilian version for optimizing sound dampening on the 787. I don’t know if they kept doing that on subsequent planes but I would expect so given how enthusiastic they were about being able to apply the weight budget to greater effect.
You need really high clock rate sensing to differentiate the arrival time for sound from microphone arrays where they are all less than a nanosecond separated from each other.
A nanosecond? The speed of sound at sea level in dry air is approximately 330m/s. So at say 3.3 kHz, the rough logarithmic middle of the audible spectrum, K=2π/lambda is 2π/0.1 m=20 π rad/m. A phase difference from a source difference k. ∆r would therefore likely be far more easily resolved than that for many physical ∆rs then, no?
Whups. Sound not light.
Sensors around 12.5 inches apart will be a millisecond separated. The actual device was from a fuzzy recollection of a picture I saw, was probably 700 microseconds across. But it was a sphere with many sensor so adjacent sensors were less than .1 ms of separation. They would have all the time in the world to calibrate such a thing.
My guess is rather than triangulation, they probably just find the two microphones with the widest phase separarion between their signals and draw a line back between them. I don’t actually know how much 3D sonic math they’re doing.
What I do recall is that it was tech that had recently reached the Cheap Enough to Use status at the time, which is about 20 years ago now?
MAybe the high clock rate it to allow it to read the output of the ADCs serially?
Given that it was McDonnell Douglas, sorry Boeing, they probably cut it.
Why don’t you give me a paper cut and pour lemon juice into it?
There are products in this space, eg https://www.crysound.com/
Very cool stuff, can be used for drone detection at up to 200m. Accuracy is not super good, unless you make mic spacing a bit large.
respeaker and https://github.com/introlab/odas might be a good starting point without having to make hardware.
Making the hardware is fairly achievable without having to do fancy things. but if you want >8 channels you'll need to make some custom interface hardware.
Steve Mould did a cool video on this: https://m.youtube.com/watch?v=QtMTvsi-4Hw
I've seen http://soundryx.com/
There's a company in Austin that uses sound for drone localization, although I forget the name
Like in this Steve Mould video, "Acoustic cameras can SEE sound" [1]?
[1] https://www.youtube.com/watch?v=QtMTvsi-4Hw
I want that but for smell.
Nobody can do that. Use dogs.
You could try training wasps.
You should visit Orfield Labs in Minnesota.
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ChatGPT tells me that it would take a very large array to detect distance with any accuracy
> It sounds like they had to reverse-engineer the MIPI protocol used on the Pi 5 to do this (since it goes through the RP1 chip), and the way it's architected, you can daisy-chain multiple QuadRF modules together, letting each module calculate it's own phase shift.
How are they planning on distributing a shared, highly precise clock for that purpose? That's already a PITA if you do QO-100 modes that need high precision, but usually there it's enough to have one good clock that you feed to the LNA... but here? Every single one of these modules needs a very precisely identical timing signal and the kind of chips you can use to multiplex a reference clock signal are pretty expensive.
check out https://QuadRF.com/docs/
So, essentially, the secret sauce is tracing a known calibration source's movement to compensate for different cable lengths or weird physical tile arrangements? Neat!
Yes-- but it's open sauce!
The visualizer reminds me of my thermal camera.
I have heard claims of devices (mostly TVs) supposedly coming with secret 5G cell uplinks built in [never heard a specific model mentioned though].
If there were more variants covering more commonly-used RF bands, people could walk around and literally check for once.
(incidentally i'm sure three letter agencies have had this sort of tech in their bug-detecting toolkit for a LONG time)
Whos paying the telcos for those 5G connections and also has the FCC been degraded so much that they would allow for undeclared radios in consumer products?
More likely 4G LTE MTM (https://www.verizon.com/business/products/internet-of-things...). It's dirt cheap and paid for by the vendor of the device it is in (usually) in the name of 'telemetry'.
I've seen so many random industrial devices and parts come into our plant that have their own cellular it's wild.
You really think these are in TVs going unoticed and someone is paying for each radio?
I have $100 devices in industrial devices that have them. In bulk, they cost next to nothing (not quite as cheap as RFID but getting there).
But in your scenario they are an integral and necessary part of the device, so it's costed in.
In a television it's an added cost and it's unclear if serving ads really can offset that extra $25-100 of hardware (and included data) you ship on a $200-1000 television.
It's also unclear to me if the low data packages they come with would be enough to serve meaningful ads to begin with. Those devices usually come with a fixed plan of 100MB/month for 5yrs (or along those lines). Modern smart tv ads are very often video or at least hi res images.
> In a television it's an added cost and it's unclear if serving ads really can offset that extra $25-100 of hardware (and included data) you ship on a $200-1000 television.
Amazon seems to have done the math and found that it makes sense to give a $20 discount on a $180 device if it lets them display very unobtrusive ads on the lockscreen. So I don't think you are correct.
Why are you assuming the primary motivator is to serve ads? Smart TVs were already caught running content ID against the contents of the screen and phoning that data home. "Routing at the edge" is the euphemism for the logical extension of that.
> extra $25-100
Your estimated costs are off by at least one order of magnitude, probably two.
Of course none of this makes much sense in a world where smart TVs have ubiquitous wifi, most consumers have one, most consumers run the stock OS, and most consumers connect it to the public internet. It would be entirely viable if not for that status quo.
My truck (Ford) has some cell connectivity that I’ve never paid for. At scale it’s likely very inexpensive.
Unfortunately, it's used to spy on you, and insurance companies are known to buy the data to profile customers or prospective customers. The good thing about Fords is that the cell modem often has its own fuse.
Secret 5G is not as common because there is a huge incentive to resell the free service. Maybe with eSIM it will be harder. Kindles uses to have a free data plan SIM.
> huge incentive to resell the free service
Not all mobile data APNs go to the Internet. You can't resell an IP service that lands on an RFC1918 network with exactly one IP:port available; the API endpoint.
Not saying I've seen this in devices, but I have built and run mobile data networks with private APNs.
Telcos sell off peak only 5g for cheap. Only to large companies that are willing to work with the limits. Often it is low bandwidth.
This is interesting. Do you have any specific examples?
No. I did see in the 5G design that that type of thing was a consideration. It may well be that phone companies aren't selling like that, however it certainly would make sense that they would be looking for companies who want a deal. Most of the cost of service is fixed, and a large number of customers want service during particular peak times and so they can serve that peak data even at off peak times such as when everyone's asleep and so if they could sell that time only that is a little bit more money. It only makes sense if those buying off peak times do have other alternatives that they would turn to instead.
The FCC is literally powerless nowadays for all intents and purposes. They've abrogated so much of their authority to the states now that they might as well be eliminated. What little authority that remains with it is bought and paid for to the point that I'm sure you could get anything "approved" if you wanted.
> has the FCC been degraded so much that they would allow for undeclared radios in consumer products?
Well... most TVs already have a WiFi/BT chipset for stuff like advertisements or, especially with Apple, high-bandwidth video streaming. There is already a radio module present, but (IIRC) you don't have to disclose what exactly that module is capable of.
You definitely are required to disclose what frequencies are used and at what power.
Uhh yes you absolutely do need to disclose exactly what each is capable of. Each radio must itself be approved by the FCC and documented
It always impresses me that technology ideas once exposed in the nefarious background of the Snowden revelations, has now become mainstream, almost passé among the technocratie, but then I remember that there is a very dominant event horizon where all technology is weaponized/de-weaponized according to the intentions of its users..
It's going to been pretty wild to see QuadRF being applied for things. I can only imagine there are weapons-technologists who will bolt this onto hunter/killer drones at some point. A lynchpin technology for the inevitable drone wars.
> I have heard claims of devices (mostly TVs) supposedly coming with secret 5G cell uplinks built
This is occasionally mentioned on HN, but I have not yet seen a specific instance of this. Please share if you know something about secret 5G cell modems used to spy on people.
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It should be more specific, it spots RC drones operated on ~5.8ghz, it won’t spot RC on 900mhz, nor cellular enabled ones.
It also appears to have a fairly narrow detection angle. This might work for spotting a drone when you already know roughly where it is, but that problem becomes infinitely harder when you have to scan the entire sky.
RF drone detection has been a challenging problem for quite a while. Lots of solid state radar/RF detection products have emerged in the space, but it is not a trivial problem. And that is for drones with active RF comms, anything flying autonomously is even harder to detect at a far enough range to actually do something about.
> RF drone detection has been a challenging problem for quite a while.
Correct, there is no bullet proof cuas system to this date.
> anything flying autonomously is even harder to detect
Not just autonomously, because even in autonomous mode you would still need other RF like gnss, but you can fly drones without any rf signature at all and utilize a pre captured images saved on board to navigate the drone accurately using its cameras (normal or thermal). In this case, rf interference won’t work, it won’t be detected based on rf signature either, you will have to rely solely on visuals and acoustic, fly at night, and only left with acoustics.. it is a very hard task from technical standpoint.
GNSS is passive and can’t be tracked, the transmitters are all in orbit.
Not tracking, jamming. A drone that has no rf dependencies as I mentioned above plus its small footprint is unstoppable, the only current limitations in drones is the endurance.
Is that a limitation of the antenna? I though QuadRF uses SDR so can see many frequencies, not just the wifi things like ESPARGOS [0]
From documentation, QuadRF: Operating frequency range of 4.9 - 6.0 GHz (C-Band).
0. https://espargos.net/
Not the antenna, unfortunately, it only operates on the range of 4.9-6ghz.
It would be great to have a wider range like other SDRs but of course the cost will increase exponentially.
https://www.crowdsupply.com/scale-rf/quadrf
I'm not super familiar with this area, but couldn't it see harmonics?
for lack of directonality?
for lack of frequency tuning
Build this into smart glasses and it would be fascinating.
I just kinda skimmed through it, so it detects drones in sky? Am I understanding this correctly? That might have some defense application considering what's going on in Eastern Europe right now.
It detects drones which send out RF signals at the same frequency band. Most drones used in Ukraine are tethered with thin optical wire exactly because one of the first anti-drone measures was to simply jam them at the frequencies the operators used.
There are some more advanced anti-drone measures at work: Like blasting them with directed high-energy microwaves to destroy the circuits.
Most drones aren't optical because optical drones sacrifice payload and distance, they're only used when broad spectrum jamming is expected. Jamming of that type is expensive and heavy enough that infantry probably won't be jamming, or light vehicles, or a lot of infrastructure.
Most light vehicles are jamming, and infantry at least have detection capability, which is why fibre is now the standard for close range.
Frequency hopping is not THAT difficult.
Brute force wide band jamming would be easy too and would make hopping ineffective. Unless drones use self tuning antennas to overcome losses, they can't hop too far away from the antenna resonance frequency, which makes jammers job easier.
Jamming broadband is a lot more energy expense than frequency hopping. Orders of magnitude.
But the jammer can be plugged in to the grid or a diesel generator. Being on the ground without flight requirements grants access to such resources.
Yes. That makes it fat, expensive and vulnerable target. There are videos of them being blown up regularly.
Which is a completely unrelated to what we were talking about.
How come? It plainly negates the "easy" part. It's not easy at all, you need to scale your signal path to the magnitude of power. I.e. the expensive part.
But such a jammer is expensive and a magnet for HARMs that only need that RF signature as guidance.
Which is a completely unrelated to what we were talking about.
How is SEAD unrelated to drone warfare? Unless you believe anti radiation missiles/drones can't target jammers.
The topic was energy expense of wideband vs narrowband jamming.
Both can be used for targeting.
So what? It's not the airborne platform with limited energy and an explosive payload that needs to do the jamming, it's the ground-based targets.
However, as pointed out elsewhere in the thread a lot of these jamming arguments are academic because drones are either tethered with a fiberoptic cable and/or navigating autonomously.
True, but they can't use directional antennas nor lots of power, and once they're far enough from the transmitter inverse square law does the rest. Ground stations always have an advantage because of higher gain antennas and more power available.
I mean, drones trailing fiber optic cables are widely documented https://en.wikipedia.org/wiki/Fiber_optic_drone
So I’m pretty sure avoiding jamming by a military adversary is not trivial, even with frequency hopping and suchlike.
FPV drones in the Russian war are generally pretty dumb devices, there's usually no frequency hopping involved to begin with. They have a lot more in common with baby monitors than with modern military comms.
Lol, even baseline DJI drone chipsets from a decade ago do frequency hopping. Many baby monitors probably do too.
You can literally see the analog video links in countless thousands of published recordings. Nobody really does the hopping with analog video.
From early in the war, sure.
> That might have some defense application considering what's going on in Eastern Europe right now.
This is a bog-standard phased-array RDF calibrated for WiFi freqs; that stuff is already in every single defense show.
Also, that's why there's jamming everywhere (to blind that kind of things) and why many UAVs are now tethered to optical fibers instead of being RF-controlled.
Yeah I think it is at every defense show, but that doesn't mean it makes it to the front lines. Defense show = super expensive. This is cheap.
Homing in on sources of electromagnetic transmissions has been a thing since at least the BV246 in 1943.
The first phased array systems date back to 1905.
We have had some time to productionize this.
Hell, the "PA" in "PATRIOT missile" stands for "Phased Array".
I'm not saying it's new technology. The patriot missile costs $4m each. None of the drones Ukraine is using have this tech.
The new thing is that it's available for purchase for a reasonable price.
Why would they put phased arrays on UAVs? They are typically using beam-forming antennas + cheap gimbals for the same purpose.
Phased arrays are nice when you want to scan a large angular surface very fast; when it comes down to optimizing RF radiation toward your ground station, a gimbal is cheaper, simpler, and works fine.
While it doesn't produce an image, not having 2D data, KrakenSDR has some cool direction finding too.
> Defense show = super expensive
Really depends; there you can see both Lockmart exhibiting multi-billions project, and 150m after some Serbian company selling jet engines for UAVs for a couple hundreds.
Very much so.
I had a friend who'd just gotten out of EE school as a non-traditional student who was working for a company that was making radars for tracking drones maybe five years before the 2022 Russian invasion.
That was an active system, similar in concept to the radars used in air defense system just scaled down and faster acting.
The one in this article is a passive system that sees the transmitter on the drone. The comm link is the obvious weak spot on the drone as it can be detected and jammed, it is fairly inevitable that lethal attack drones that work anonymously will be widespread as a result.
> that sees the transmitter on the drone. The comm link is the obvious weak spot on the drone
Isn't most drones run by fiber optic nowadays around the front-lines though? Can't really jam those, but maybe still detect it somehow?
According to CivDiv's channel about 70% of the drones used are still RC FPV drones. They are cheaper longer range and have a slightly simpler supply chain. Fiber optic cable prices have exploded because of the war.
glad to see someone giving a source. a lot of people here heard of fiber optic drones and decided that now 100% of drones in Ukraine are using those
If you count recon and droppers that can use distance to avoid jamming, sure. One-way applications are increasingly fibre.
Can you back this up with any authoritative sources?
The visualizer app reminds me of the same UI / output you get from acoustic cameras.
I wonder if this tool can help with EMC compliance testing. My TinySA needs an LNA, so I wonder if this has the required noise floor.
I don't see any professionals turning to this for EMC/EMI testing, they already have all the test equipment for that job.
How about "non-professionals"? It could be useful to check device before sending for pre-compliance / compliance checks and save money - that would avoid very expensive iterations.
But there are already benchtop or handheld signal analyzer for that purpose.
This seems more like a tool for checking across entire large assemblies like an entire building, car, aircraft, etc, for unknown sources. If you have an individual discrete device that you're already testing, just using traditional instrumentation seems reasonable, but on a large, complex assembly, I can see it being useful. Also useful for things like detecting if a particular antenna is working without actually going up there to measure near it; if you have a MIMO setup with multiple antennas, this might make it easier to check if all of them are working correctly when mounted in inconvenient areas.
That's absolutely missing the point. EMC/EMI testing is expensive, time consuming and requires scheduling and experiment design.
Being able to do local soft-run testing on-site to be sure that you eliminate the easy 90% of issues before you get to the lab would be a huge win.
I think that for a single device, this probably wouldn't help much over just having a more traditional signal analyzer, either benchtop or handheld. If you know what you're testing, just using a signal analyzer around it will give you a good first pass picture of emissions, and probably be much more informative and precise than this.
This seems more useful for finding unknown or hidden RF sources, for instance looking thorugh an entire building to find unknown RF sources, or maybe a whole complex assembly like a car or aircraft.
It is surreal to me that a comment stating that being able to do a certification pre-check on site before booking testing got downvoted.
Sure, maybe this isn't the device for that... but the idea that what I said was objectionable is just bizarre.
I don't think it's any good for that. It's relatively narrowband and not the frequency you usually have issues with EMC on (5 to 6GHz - unless you are specially transmitting on this frequency you are unlikely to emit anything there).
It is crazy for me to see super secret military tech from 30 years ago commoditized to a system cheaper than gaming console. What a time to be alive!
I don't think it was ever (past 30 years) particularly secret? The general concept is long (100+ years) established. However pulling it off used to be exorbitantly expensive.
One use of focused RF detectors is locating hidden cameras via scanning their WiFi or Bluetooth RF signals.
>It can see WiFi through walls
I don't understand what this is trying to say. Everyone who has ever used wi-fi knows that it works through walls. You try to connect to a wi-fi in an apartment, and there are dozens of other networks showing up.
So this headline just seems...meaningless?
We know the definitions of "see" and when we take it to be in the "visualize" sense, it tracks for me.
I'm guessing if you can "see" Wifi through a wall, you can also infer some things about what's behind the wall, because the signal will have certain obstruction patterns. It becomes an xray.
It's RF vision, it let's you visualize RF sources as a coloured blob overlay in real time.
Would something like this work at much lower frequencies? Being able to see RF at 3-30MHz would be fantastic for hunting RFI in the amateur radio HF bands.
Neat! SDRs have been available at reasonable price points for some time but the processing power to engage with wifi and other digital signals has been somewhat elusive. Assuming RAM can be purchased in the future, I think we might see a lot more prosumer-targeted devices for doing raw signal analysis in the future.
Do you have specific SDR in mind? I thought the v2 dongle doesnt have the range of Wifi? SDR is something Ive just recently want to learn to help me understand electromagnetism
The original quote for a single tile was $50-$100
They came out at $500
Being off by a bit is fine. Being off by 5x to 10x is.. Yikes.
It's actually sold on their Crowd Supply for $99 per 4-antenna RF tile, just as the said on their website.
See the 6-pack: https://www.crowdsupply.com/scale-rf/quadrf#products
Prices have gone a little insane in the last year though too to be fair to them.
The Pi alone... just today, someone over at Reddit spotted a Pi 5 being sold for 350$ [1].
[1] https://www.reddit.com/r/homelab/comments/1uso8u1/insanity/
I thought that might just be Amazon resellers capitalizing on marks being too lazy to go off site at first when they were $280 at Microcenter (still crazy expensive). [0] Then Adafruit had them for the same $350! [1] And it really does seem to be driven by the ram too the 4 GB model is only $130 (or $104 at MC).
[0] https://www.microcenter.com/product/702590/raspberry-pi-5?rd...
[1] https://www.adafruit.com/product/6125?src=raspberrypi
Just like eBay, an Amazon listing for a certain price does not mean the item is actually /selling/ for that price -- especially with badly-coded dynamic re-pricing algorithms hooked into listings these days.
It's not completely out of line with other RPi sources listed on the RPi Foundation's own site. It's the same price as Adafruit for example but about $50 more than Mirco Center (though that is for instore pickup only so only for people lucky enough to live close to one).
The Pi 5 has always been a horrible value, even when you could buy it at MSRP.
$500 is a surprisingly good price for a 4x4 mimo SDR.
It looks like it has 4 tiles on it, no?
Yea its mimo 2x2.
Point still stands that they initially said it would be $50-$100. And its going for $500.
I mean if a single tile is 50-100, then 4 is 200-400, so it's not that far?
I think GP misspoke and it's actually four antennas in one tile for this thing.
With the end of easily available rtl-sdr dongles it's a relief to see someone has wrung such exceptional RF instantaneous bandwidth out of an RPI alternative interface. I really hope use of the camera interface for RF takes off.
Historically these have been quickly shut down without much of an explanation.
Please elaborate. There are literary step-by-step videos on how to build these. E.g. https://www.youtube.com/watch?v=g3LT_b6K0Mc
Phased array radars are export controlled in the US. It doesnt mean its illegal to build or own, but it might be illegal to sell in some cases
I thought I remembered even seeing public Git repos with passive radar code that ended up getting shut down due to export controls?
Yeah, Kraken SDR removed some functionality due to these concerns, if I remember correctly.
Odd, because export controls don't generally apply to published material (like open source software), but maybe they were worried that because they were also selling the hardware they could have issues due to the combo being export controlled.
Ah, found discussion of what exactly it was they pulled, it was the passive radar code: https://www.reddit.com/r/RTLSDR/comments/yu9rei/krakenrf_pul...
And indeed, they confirmed that they believe the open source software should be OK, but they had concerns because they also sell the compatible hardware: https://nitter.net/rtlsdrblog/status/1591657740229046274
As someone who works daily with export-control-adjacent hardware and software, my experience is that people tend to aggressively self-censor to a far higher standard than export control regulations actually require. The perceived headache of drawing the ire of whoever it is the enforces this stuff (which as I type this comment I'm just realizing I don't know who specifically is responsible for that) is so scary that people don't want to take any risk at all of being targeted.
If you don't self censor in these cases the law will find you somehow. How change so they get you next time.
Not always, but pgp wasn't exported that way until not long before there was good demand for for encryption in e-commerce anyway
Wonder which LLM would be happy to vibe code it back (not sure if it would be able to pull it off tho).
This is not a radar, only a receiver.
It can still be in scope:
> Direction finding equipment for determining bearings to specific electromagnetic sources or terrain characteristics specially designed for defense articles in paragraph (a)(1) of USML Category IV or paragraphs (a)(5), (a)(6), or (a)
ITAR part 121.
The "specifically designed for defense" probably makes this OK, but IANAL.
The covered materials are very broad, though often limited to equipment built "for purposes of", like in this section.
Title 22 Chapter I Subchapter M Part 121 - The United States Munitions List - Category XI Paragraph b
Electronic systems, equipment or software, not elsewhere enumerated in this subchapter, specially designed for intelligence purposes that collect, survey, monitor, or exploit, or analyze and produce information from, the electromagnetic spectrum (regardless of transmission medium), or for counteracting such activities.
At what point does a microphone become an intelligence device, when we have so many types of microphones. Is it an arbitrary label I can add or remove to a product? Will it apply equally to large manufacturers?
It's a matter of intent, which will ultimately be litigated in court and is going to depend on a lot of surrounding factors.
> specifically designed to collect or analyze information from the electromagnetic spectrum
Wouldn't that apply to every spectrum analyzer?
Where did your quote come from? The comment you're replying to says "specially designed for intelligence purposes". The word "specifically" doesn't appear.
Do share some more details please
Probably because the people working on them get job offers that come with clauses about not working on this stuff publicly.
The explanation may be spelled ITAR.
> If the open source community can come up with something like this, just imagine what governments are capable of.
Since ~2022 and accelerated by the Russian aggression against Ukraine, governments are now behind both private and open source for frontier technology.
The companies that captured government contracts in the last century can’t move fast enough to bring tech into the government and national technology policy and funding is collapsing compared to the private sector
That’s new in history
Open source is the future. If everyone can work on it, we get better results for cheaper.
Open source doesn't mean the end of competition, since we are a competitive species.
I think the future economy is going to be some sort of UBI + large open source projects
Only if everyone wants to work on it, which seems unlikely for this project and we already know is a fail for security issues in open source.
This has me thinking that fiber optic drones using this technology might be able to discover the location of signal-jamming equipment. But only for the good guys.
What constraint limits this to 5 - 6Ghz? Is it the antenna? Processing?
It's a really neat device, but people should realize that it has a very narrow visibility.
Antennae, and the front end that feeds into the SDR.
The lower the frequency, the bigger the antennae need to be (more or less) so a 2.4gig array would most likely be 2x the size of a 6ghz array.
Sigh, fine. I will buy another radio gadget on crowdsupply.
I recall reading the original research paper from a student who made the same RF ‘camera’ here in hacker news.
if it can spot/track drones that is a marketing opportunity for airports around the world that have to deal with drone nonsense which shut down flights for days
Most major airports will already have a counter-UAS system, it's a huge industry.
One big issue with radar is that it has the same problem pilots and human observers do: it struggles to distinguish drones from anything else in the sky (birds, balloons, planes, etc.). This is an active and improving research space, but by and large with radar, when your pilots report a drone, you still don't know how to figure out if it's the typical mis-identification or something real.
I'm reading about pilots spotting drones during takeoff/landing that the airport didn't know about
And I've read about airport shutdowns in UK and US without a single arrest which is why it keeps happening
So whatever system exists, apparently not good enough
Right, there are two problems there:
* Pilots are very concerned about life and safety and are heavily exposed to drone “incident” related anecdotes, so they err far on the side of caution with drone sightings. Which is to say a very low percentage of them are real.
* Poorly implemented cUAS systems, especially ones based on passive or active RF locating (radar) can actually make the problem worse: they hallucinate everything into drones, pilots hallucinate everything into drones, and now everything is a drone. This also happens frequently when people try to repurpose military systems (which are usually designed to operate in significantly less crowded environments and trigger at the slightest hint of an issue, due to mostly orthogonal-to-airports threat models people discuss at length on this thread like “dark drones”) into urban use.
This type of array based directionfinding system is cool and it could work as a small ingredient in a drone detection system, but it’s not anywhere near the state of the art in the space and most airports are probably already ahead of this to some extent.
Phased array antennas (in use since the 1960s) and AESA (in use since the 1990s) are very mature tech that RF engineers are well aware of.
This gizmo is primarily interesting that it's pre-packaged at a price that hobbyists can afford.
If would likely need to track them well (not sure from this article/video if that's the case?) to be useful in that scenario...
Drawing a splodge in roughly the location (not sure if there's range info either? I doubt it if it's passive) overlaid on the video likely won't cut it...
Yes, primary radar has been useful for detecting airspace incursions since 1939. Nothing new here.
The difference with this kind of tech, though, is tracking down the operator.
There are more way advanced systems for cuas, where they infuse radar and visual and acoustic plus now AI to minimize the false positives, but practically speaking, they are not bullet proof and still fail. RID (remote ID) is a way to have a cooperative communication and was mandated in US, but there are ways too to spoof it and cloak it.
Yeah RemoteID is trivial to spoof using an ESP32. Most hobby pilots I know simply don't comply with RemoteID. And bad actors certainly won't purchase a $75 device to add to their drone.
It does become a bit more difficult with consumer grade off the shelf drones because it's built in. Still defeatable by the determined of course.
Only the ones that use radio for control. The fiberoptic ones are "dark" to this setup.
And yet since rtl-sdr times we have passive radars as an option as well https://www.rtl-sdr.com/tag/passive-radar/
Passive radar is fine for gigantic airliners with all regard for efficiency, none for radar cross section, and that fly above most obstacles. For drones you might be trying to scratch signal not only from below noise floor, but at the edges of quantization.
Super cool concept!
Now imagine thousands of these flying around in low earth orbit.
I was almost through the checkout flow last week before I realized that this configuration only supports a relatively narrow frequency range.
I work primarily in sub-GHz radio. Please wake me up when they launch their LoRa version, that would be an instant purchase for me.
set that alarm
https://news.ycombinator.com/item?id=48861717#48864989
> If the open source community can come up with something like this, just imagine what governments are capable of.
Why so bullish on government? The department of motor vehicles is capable of being better, but they aren't.
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Outside of spotting ukrainian drone operators in bunkers, why would you need or want this?
I want this. I have Wifi door lock too far away from base station. It was often stuck in a loop trying to connect to neighbours' Wifis. By try and error I managed to block those using metal foil, but it was hard work.
That would seem to be a design flaw in the lock. It shouldn’t be trying to connect to random WiFi.
I blame micropython. Because it is reprogrammed by me myself. Original was much worse, because it always asked from China if it can open the door.