Top
Best
New

Posted by speckx 1 day ago

QuadRF can spot drones and see WiFi through my wall(www.jeffgeerling.com)
676 points | 217 commentspage 2
aeturnum 1 day ago|
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.
miranaproarrow 1 day ago|
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
ww520 12 hours ago||
One use of focused RF detectors is locating hidden cameras via scanning their WiFi or Bluetooth RF signals.
tamimio 1 day ago||
It should be more specific, it spots RC drones operated on ~5.8ghz, it won’t spot RC on 900mhz, nor cellular enabled ones.
nullpxl 46 minutes ago||
I'm not super familiar with this area, but couldn't it see harmonics?
brk 1 day ago|||
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.

tamimio 1 day ago||
> 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.

adolph 1 day ago|||
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/

tamimio 1 day ago||
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

_davide_ 1 day ago||
for lack of directonality?
relaxing 1 day ago||
for lack of frequency tuning
mmaunder 1 day ago||
Historically these have been quickly shut down without much of an explanation.
random3 1 day ago||
Please elaborate. There are literary step-by-step videos on how to build these. E.g. https://www.youtube.com/watch?v=g3LT_b6K0Mc
ac29 1 day ago||
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
Onawa 1 day ago|||
I thought I remembered even seeing public Git repos with passive radar code that ended up getting shut down due to export controls?
lambda 1 day ago||
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

0xffff2 23 hours ago|||
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.
bluGill 23 hours ago||||
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

dzhiurgis 23 hours ago|||
Wonder which LLM would be happy to vibe code it back (not sure if it would be able to pull it off tho).
RealityVoid 22 hours ago|||
This is not a radar, only a receiver.
thomashabets2 21 hours ago||
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.

cucumber3732842 5 hours ago|||
Probably because the people working on them get job offers that come with clauses about not working on this stuff publicly.
illliillll 1 day ago|||
Do share some more details please
jkuli 22 hours ago|||
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.

go_artemis 22 hours ago|||
> specifically designed to collect or analyze information from the electromagnetic spectrum

Wouldn't that apply to every spectrum analyzer?

fc417fc802 18 hours ago||
Where did your quote come from? The comment you're replying to says "specially designed for intelligence purposes". The word "specifically" doesn't appear.
jkuli 22 hours ago|||
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?
fc417fc802 18 hours ago||
It's a matter of intent, which will ultimately be litigated in court and is going to depend on a lot of surrounding factors.
knorker 1 day ago||
The explanation may be spelled ITAR.
bigtech 23 hours ago||
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.
ericye16 1 day ago||
Sigh, fine. I will buy another radio gadget on crowdsupply.
stevage 17 hours ago||
>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?

Barbing 17 hours ago||
We know the definitions of "see" and when we take it to be in the "visualize" sense, it tracks for me.
roncesvalles 16 hours ago|||
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.
stevenhuang 15 hours ago||
It's RF vision, it let's you visualize RF sources as a coloured blob overlay in real time.
slicktux 1 day ago||
I recall reading the original research paper from a student who made the same RF ‘camera’ here in hacker news.
mschuster91 23 hours ago||
> 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.

mrtnmcc 22 hours ago|
check out https://QuadRF.com/docs/
mschuster91 21 hours ago||
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!
mrtnmcc 20 hours ago||
Yes-- but it's open sauce!
kristianpaul 1 day ago|
And yet since rtl-sdr times we have passive radars as an option as well https://www.rtl-sdr.com/tag/passive-radar/
fer 21 hours ago|
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.
More comments...