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Comment by captainmuon | Hacker News Reader

I wonder what the normal or non-military use cases of this code could be? Planespotting? Indoor navigation?

Tracking anything you might track with an active RADAR, but without needing a permit to operate a RADAR emitter. The ability to track 'stealth' aircraft is just a niche. Similar techniques are used to measure atmospheric density (for meteorology) using the known signals from GPS satellites.

Maybe as a human presence detector for security, control of musical instruments, monitoring vital signs. In all those cases you probably don't want a radio emitter near other equipment (especially in a hospital). For security systems, say as a human presence detector, you may not want to advertise your security system has a radar sensor by broadcasting RF. I think there are some research papers on using passive radar for vital signs monitoring. Indoor localization would be a good use also.

A lot of those are based on wifi as the illuminator

I have the same question. Kraken's main product is a 400$ "software defined radio for applications such as radio direction finding and passive radar" [0].

At that price point they'd have to sell quite a few of these to make a living. So who's buying these, and what for?

[0]: https://www.krakenrf.com/product-page/krakensdr

I bought one to play around with. I've located radio transmitters by driving around and used the passive radar to track cars on a highway and airplanes at an airport.

There’s a decent group of amateur radio enthusiasts who buy these things to track illegal operators.

It’s more done for sport. A low power beacon is purposely hidden somewhere and teams try to find it first.

My local club does foxhunting activities but also has been trying to identify a set of transmissions meant to disrupt the repeater’s operation.

At least three members bought krakens at least in part to find the perpetrator. To me it’s a pretty interesting cat and mouse game. It seems like the illegal transmissions are mobile which has prevented success at stopping them.

Another user case is non-malicious interference. Sometimes something is radiating a strong harmonic because of a corroded connector, etc, and the source can be identified with doppler direction finding equipment.

Finding a culprit in a repeater war is a more difficult thing to do, because what do you do with the person once he's identified?

> because what do you do with the person once he's identified?

Hand the evidence over to the FCC. The FCC isn't going to proactively go after someone, but they're more than willing to take cases and issue fines if someone has already done most of the legwork.

Example: https://docs.fcc.gov/public/attachments/DA-19-989A1.pdf

They would do great in Ukraine right now for direction finding shitty Baofeng UHF radios ru have to use after their general embezzled funds for development of Azart system

https://twitter.com/RALee85/status/1184964805565792257

>Interfax reports that the Deputy Chief of the General Staff and the most senior communications officer in the Russian military, Colonel General Khalil Arslanov, has been arrested for fraud in relation to the purchase of special equipment.

>The investigation isn't limited to 2.2 B RUB worth of theft, but also to fraud related to contracts for the Azart comm system built by NPO Angstrem JSC and Yaroslavl Radio Plant. Of 18 B RUB spent on the radios, 6.5 B RUB might have been stolen due to artificially high prices.

Yep, I have a Kraken and can confirm it is fantastic for DFing shitty Baofengs, especially when they're being used as HAMMER-style acoustic modems for something chatty. Practically the best possible scenario for easy DF. Perhaps logically, even though chirp spread spectrum isn't actually FHSS, it struggles a lot more with LoRA transmissions.

$lastco (defense contractor) used something like that for localizing various EMF (cell phones, drone controls, RC remotes, and other potential IED triggers) as part of one of those "smart soldier" DARPA programs.

There's definitely demand in the defense-adjacent space.

The most often cited are things like the fire department figuring out which parts of a burning building have people in them, or a hospital noticing when a patient tries to get out of bed on their own.

Tracking rogue drones maybe. Also stranded jets.

Drug smuggling. If you don't need to be covert then you could just use active radar, right?

If you have nothing to hide?

> If you don't need to be covert then you could just use active radar, right?

Passive radars can be used to track emissions sources of which you have no specific knowledge e.g. you're looking for a ship or rig, but you either don't want to ping it, or you are looking for its rough location, or you literally don't have the hardware for an active radar at the range involved.

European SAR space radar already covers earth every few days. Results are free and open.

Do you have a link to the data?

https://scihub.copernicus.eu/dhus/#/home

http://step.esa.int/main/download/snap-download/

People have done PR off the French space radar transmitter

You have a much more active imagination than I do.

Others have linked the code and an article about someone trying it out. What you can do with this is that you wave around two yagi antenna. You point one at a broadcast source and an other at something flying in the opposite direction from the broadcast source. If all the stars align and the system works you then get the range, and the dopler. The measured range is the full distance from the broadcast source to the object and back to you.

This is not a radar where the user gets a display full of tracks in front of them. One maybe one day might develop something like that from this core.

Even if it were a stealth radar like that it is very dubious how it would help a drug smuggling operation, or why they would bother with it at all.

> What you can do with this is that you wave around two yagi antenna. You point one at a broadcast source and an other at something flying in the opposite direction from the broadcast source. If all the stars align and the system works you then get the range, and the dopler.

This is one interpretation, but it's actually pretty reliable.

> This is not a radar where the user gets a display full of tracks in front of them

You actually do get a full radar plot.

See the video at the bottom of https://www.rtl-sdr.com/krakensdr-field-reports-and-software... for a complete tracking of a weather balloon.

That’s DoA not PR though I believe, since the balloon is a transmitter

Yes you could be right there.

That was their original intent - to use the other receivers as well

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