Lithuanian startup launches open-source network to detect Shahed-type drones (lrt.lt)
98 points by giuliomagnifico 5 hours ago
lnsru an hour ago
Or it is a public stunt? I am naysayer engineer. Build acoustic detection system for anomaly detection in manufacturing line. It worked with studio level equipment with lots of noise filtering measures. First challenge was to have microphone listening to the right place and getting reliable signal. Second challenge was to amplify the right signal to a level where the features could be extracted. I doubt an old android with dirty microphone can detect anything reliably.
tristanj 4 hours ago
Shahed drones have increased in altitude from ~500m at the beginning of the Ukraine war to 2000-3000m, which is a 4x reduction in noise on the ground. The higher the drones are, the less noise they make at ground level, and the less effective this ground-based microphone system will be. The drones have moved to elevations to make them more difficult to target with ground based weapons. Reductions in ground noise are a secondary effect.
The latest versions of Shahed can reach 5000m in altitude, which would largely be inaudible on the ground.
dghlsakjg 2 hours ago
At those higher altitudes they are trivial for radar to detect, and from farther away too. They are adapting cheap commodity used marine radars to get this done in some places
I suspect the Shaheds are going higher to mitigate AA ground fire. Higher up you have to send a missile or interceptor up.
It’s a trade off.
rdtsc 2 hours ago
And interceptors are more expensive than Shaheds. A $100k interceptor (guessing here) to shoot a $10k Shahed can be an acceptable deal for the side launching the Shaheds.
dghlsakjg 2 hours ago
energy123 2 hours ago
lnsru 2 hours ago
gnerd00 an hour ago
> ~500m .. to 2000-3000m, which is a 4x reduction in noise on the ground.
Radiative power drops by the square of the distance? Does anyone with a real physics background start demanding authority on a soapbox like this?
inglor_cz an hour ago
Could you simply use small cheap balloons with microphones to listen in higher altitudes? Or even small drones that carry the microphones with their own engine noise masked out?
Edit: as others say, plain radar will suffice.
anovikov 4 hours ago
It's not about "can reach", it's fairly easy to get them to fly even higher. It's about danger of interceptors vs danger of detection. Today's Ukrainian detection network (based on radars) is so dense there is no way to hide from it anywhere, anyway, so high altitude wins.
Hackbraten 3 hours ago
> It's about danger of interceptors vs danger of detection.
What's with that "vs" trade-off?
You're saying avoiding detection requires high altitudes.
What do interceptors have to do with that?
anovikov 2 hours ago
warumdarum 4 hours ago
So film the sky during charging and run a llm on it?
Neywiny 3 hours ago
Or an image detection model. Fraction of the compute and can run even on edge embedded. And easy to train with your own data
kklisura 2 hours ago
dghlsakjg 2 hours ago
Clouds and nighttime are a barrier to visual detection. Even with good effectiveness the conditions needed for that would mean that you have far less than 50% uptime, and your downtime is predictable to your adversary.
A cheap radar takes an order of magnitude less power to run on hardware that is cheaper than an LLM and can see way farther than a camera.
energy123 2 hours ago
MiracleRabbit 4 hours ago
If these Shahed drones have a propeller they should have a brutal signature between 0-250Hz as they are moving a lot of air. And if the engine speed of the Shahed stays constant it will be even easier to detect it ("Angry lawnmower sound".. but that's only the high frequency part of it).
There are extremely sensitive differential pressure sensors (like SDP600-25Pa) available from Sensirion that aren't overly expensive.
Use one differential side and connect it to a kitchen funnel for directional listening the other one to a plastic bottle with a tiny hole in it. This way the sensor will "Null" out the environmental pressure (which the bottle follows very very slowly) from both inputs. It then only will pick up everything high frequency which is left over (and the bottle cannot follow because of its small hole).
This way I was able to detect washing machines that have a physical link to a house from many hundred meters (machine spinning -> house wall shaking -> pressure waves) away. The speed pattern of washing machines when spinning is very unique (several steps over many seconds).
Add this with some GPS PPS frame timestamping and you should have a nice tracking network that doesn't require a lot of bandwidth. But maybe the setup must switch to analog differential pressure sensors as these Senirion-I2C sensors do not have a Sync ping for super precise timestamping.
customguy 3 hours ago
> Use one differential side and connect it to a kitchen funnel for directional listening the other one to a plastic bottle with a very very small hole in it. It will pick up everything high frequency that's different to the environmental pressure.
Nevermind drones, and war, that's all fine; but I need to know more about this. Is there a phrase or name for this I could use to find more information, maybe example schematics?
MiracleRabbit 3 hours ago
The Sensirion SDP600-25Pa speaks I2C and only has a handful of primitive commands. Add this and 3.3V and you are done.
I'm 99.5% sure if you throw Claude with a datasheet on it will Slop out working code for a ESP32 with ESP-IDF.
Hnrobert42 3 hours ago
Interesting! There are a lot of super loud cars in my urban area. I want to catalog where and when they drive, so I can stand on the side of the street and shake my cane at them.
brookst 2 hours ago
I’ve always dreamt of building a mesh network of loud vehicle detectors that would map current loud noises and track where loud vehicles live, coupled with very powerful parametric speakers. So when e.g. the network detects a loud motorcycle at 3am anywhere in town, that live sound is instantly played at high volumes targeting only homes where other loud vehicles live.
Somehow there has been little VC interest in this idea.
warumdarum 2 hours ago
https://freesound.org/people/PicassoCT/sounds/850225/
Curmudgeon Ai?
custardguy 29 minutes ago
The equivalent noise density of the sdp600 is 10^-2 Pa/sqrt(Hz). While the noise density of a typical microphone is 10^-6 Pa/sqrt(Hz). At same 50hz low frequencies. So either you're full of shit and a high quality microphone is x10000 more sensitive than this sdp600 sensor, or I'm not understanding what you're saying.
amluto 2 hours ago
What’s the frequency response of that sensor? The datasheet says nothing.
MiracleRabbit 2 hours ago
Honestly: don't know.
My experiments never had a dependency on linearity.
amluto an hour ago
ejanus 3 hours ago
Interesting! I will like to see your circuits, if any.
MiracleRabbit 3 hours ago
Not much circuits needed.
The SDP600-25Pa speaks I2C and only has a handful of commands.
Just read it out with a microcontroller you love (like ESP32) and send the samples to a host for analysis. The ESP32 has limited I2C time stretching capabilities limiting it in the highest resolution modes of the sensor - but often that's not a big factor.
To not overwhelm the poor processor and Wifi maybe better a bunch of frames (like 512 or more).
ShinyLeftPad 2 hours ago
Doesn't wind fool this?
MiracleRabbit 2 hours ago
Theoretically wind can be Nulled with a 4-way water splitter that are placed in 90° angles (+ a connector at the bottom to the sensor). As long they are orthogonal the wind pressure coming from one side will cause a negative pressure on the opposite.
Only pressure waves coming into all holes at the same time will reach sensor.
Never tested it. Only a Gedankenexperiment as Einstein would say.
stavros 3 hours ago
Isn't detecting pressure waves in air exactly what microphones do?
MiracleRabbit 3 hours ago
Yes. But they usually are not performing very good between 1-250Hz.
Sensirion is using a thermal flow-sensing principle method which is basically a heated plate that cools/heats up when air passes it - making it extremely sensitive in this range.
dzhiurgis 2 hours ago
Nice. And instead of smartphones, dedicated sensor using esp32 makes more sense imo.
kamranjon 2 hours ago
For those interested there is an open source radar based phased array project here: https://github.com/NawfalMotii79/PLFM_RADAR
I may have even discovered it from hacker news, I forget now.
kklisura an hour ago
I remember seeing this on HN when it was first submitted. I honestly think that project is either a scam, an elaborate hoax, a cover for a Chinese company selling radar systems or a three-letter-agency honeypot.
The files [1], [2], [3] on Github (once featured on README and on some articles) depict what I presume is a Chinese built radar which you can see here [4], [5]. I also suspect this might be a honeypot since Instagram - of all places - is full of accounts offering these radars [6], [7]. Some of the contributors on that projects are heavily leaning into AI. Git project history is suspicious. Discussions on the issues seem very artificial. I remember having bunch of notes on this project, but can't find it now. Just looking at it from outside, nothing about it seems real.
[1] https://github.com/NawfalMotii79/PLFM_RADAR/blob/main/docs/a...
[2] https://github.com/NawfalMotii79/PLFM_RADAR/blob/main/docs/a...
[3] https://github.com/NawfalMotii79/PLFM_RADAR/blob/main/docs/a...
[4] https://www.cloudwalkerfpv.com/product/CW-t20.html
[5] https://www.militarysignaljammer.com/supplier-4701497-survei...
tpolm 5 hours ago
I wonder how this system can be protected from spam - if anyone can send data there, enemy can, too
embedding-shape 4 hours ago
I feel like if/once they reach the number of expected participants (10k), it'd be easy to filter out the spam as long as the majority are truthful.
tristanj 5 hours ago
SpaceX received a $4 billion military contract to do this, but with radar and from orbit.
Aboutplants 3 hours ago
Multi billion dollar spend to “see” $2,000 aircraft and try to shoot it down with multi million dollar equipment. The speed to produce and cost effectiveness of these drones are seemingly at a massive advantage right now vs Defense capabilities and straight up cost and looks to be that way for a good while.
zer00eyz an hour ago
> Defense capabilities and straight up cost and looks to be that way for a good while.
You are correct, that today, we (USA) lack the capability to defend against this threat in a meaningful way.
> Multi billion dollar spend to “see” $2,000 aircraft
Look at how we deploy SOCOM assets today: smaller teams in the field far from fixed detection, a satellite to do this job, allows it to be tasked rather than having to deploy more, fixed detection equipment.
As part of a larger system it would be integrated by software: see the "Lattice" project from Anduril.
> and try to shoot it down with multi million dollar equipment.
DAWG, (Defense Autonomous Warfare Group ) has requested a billion dollar base budget and 54 billion of flexible spending (More than the USMC per year) for 2027.
There is also the "Replicator" program (I think headed for phase two) to get unit costs back down, and volume up. Facets of this are bleeding into other spend. Andurill openly talks about unit costs, and how few tools are needed to put together their low cost missiles (still more expensive than drones but... headed in the right direction).
As for the astronomical size of that budget: it's cheap to build an idea, what is hard is testing. The Ukrainians have a massive advantage here, in that they ship these things to the front line. It's much cheaper to trial things when you don't have to buy something to blow up, repeatedly.
The US military has been falling behind for 25 years now (especially the navy: if you want to understand why it has become schrodinger's straight read this https://en.wikipedia.org/wiki/Millennium_Challenge_2002 ) and I think what is going on in Ukraine has been eye opening for them.
dzhiurgis 2 hours ago
Apples != oranges
Avicebron 4 hours ago
As much as I like to point and guffaw at "bad evil rocket man" the from orbit bit is doing a massive amount of lift (pun not intended) for that price.
nefarious_ends 3 hours ago
How is Elon evil?
brookst 2 hours ago
snovv_crash 3 hours ago
reboot81 4 hours ago
Wouldn’t a purpose built Esp32 with microphones aimed at the sky do a better job? It would be always on, better directional targeting.
rdtsc 4 hours ago
I believe Ukrainians had already deployed such a system. This is specifically designed to use old Android phones already sitting in a drawer somewhere without any other use, and most importantly by anyone without technical skills.
k4rli 2 hours ago
Sounds like a simple app with mic input being sent to a yamnet-like audio classification model for a single target detection. Hardly anything innovative?
dzhiurgis 2 hours ago
AFAIK started by a fellow HN’er
AIcanbiteme 3 hours ago
Baltics are very involved in the war in Ukraine, for instance, Slovenia started NAFO.
nxpnsv 3 hours ago
Slovenia is not baltic