Hacker News

Turning every radio into a radar(tiaminetworks.com)

44 points by hasley 4 days ago | 9 comments

Someone presented a passive radar system using an RTLSDR receiving TV broadcasts reflected off of nearby planes at a 2017 GNURadio conference. If amateurs can do it, you can bet the military has already designed, built, tested, deployed, and retired a similar system.

This isn't exactly a new subject, the same concept powered the first radar guided missiles in the 1940s (enemy is illuminated by a ground or airborne radar, missile tracks the reflection).

I'm fairly certain I've already read an article in an IEEE magazine talking about this topic (passive radar via cell towers) a few years ago.

[–] rpcope1 1 hour ago

KerberosSDR and later KrakenSDR are precisely this, and the guy behind it got a spanking after putting up a passive radar implementation that actually works ok publicly on GitHub sometime in the pre-AI era. Supposedly it was considered an ITAR issue, but the similar MLAT capability instead of phase coherent sensing like you get with a Kraken is basically deployed everywhere today (all of the ADS-B nodes that feel FlightAware, FlightRadar, etc.) It's certainly not novel and not in the way TFA wants to paint it.

[–] kooi 3 hours ago

I interviewed at company and their project was applying the music algorithm to find covert radio transmitters.

They were direct sampling the RF signals and running them through a bunch of H100's to get the algorithm to operate near real time. (They were quite proud of their 20 or so H100's)

Maybe this post is about that? It really lacks any technical substance. A bunch of corpo-talk is your ask me.

They probably throw all the signals, phase information into a ML model. But likely think the model inputs are very proprietary information so they just say ~ML will solve it~.

https://en.wikipedia.org/wiki/MUSIC_(algorithm)

[–] Stevvo 1 hour ago

I'm not usually one to notice when I'm reading an article written by AI, but this one is really bad. Tone put me off from finishing it.

[–] RachelF 5 hours ago

This is not new as the article claims: Passive radars using FM broadcast and 2G GSM were used in the 1990s Yugoslav war.

[–] alwa 5 hours ago

> For network operators, it raises a different question: could the infrastructure that already generates subscriber revenue also generate a second, sensing-based revenue stream?

Are there people who experience positive emotions in reaction to sentences like these? I just… even in my days when I thought social good came from states/organizations downward rather than from humans upward… even then, when I thought a God’s-eye view was achievable, that more and better measurable data were the way to get there, and that the main barrier to effective social regulation was poor legibility… I feel like even then this would ring craven and avaricious to me.

[–] kragen 4 hours ago

Craven?

[–] alwa 4 hours ago

Oops, yep. Typing fast and thinking sloppily. I had in mind something closer to “exploitative” or “opportunistic.” Maybe it was my cravin’ for dinner speaking…