from Hacker News

Homemade polarimetric synthetic aperture radar drone

by picture on 2/17/25, 1:22 AM with 60 comments

  • by colonCapitalDee on 2/17/25, 6:44 AM

    > Recently small FPV drone prices have dropped a lot. Small 5 and 7 inch propeller quadcopters can be bought for about 100 EUR from China (not including battery and RC controller). Despite their small size they are able to lift about 1 kg or even heavier payload which is plenty for a small radar.

    The price dropped because China is selling these things by the truckload to both sides in Ukraine. China is benefitting from the economics of scale, Russia and Ukraine are each burning through on the order of 100,000 of these things each month and most components are sourced from China

  • by farhanhubble on 2/17/25, 4:32 AM

    As a DIYer myself I am awed by how much Henrik has managed to flesh out in terms of complexity: signal processing, hardware, GPU acceleration, and algorithmic optimizations. I wish the HN community had some award for such incredible feats.

  • by geokon on 2/17/25, 3:41 AM

    This is actually the first time I've seen the SAR algorithm explained. Every SAR project I've seen glosses over this part.

    Wonder if anyone else has seen more resources on this? Going to try to digest the linked paper.. https://topex.ucsd.edu/rs/sar_summary.pdf

    And in the end it seems you can bypass a lot of the position problems with autofocusing! First time seeing this part too :))

  • by fisherjeff on 2/17/25, 5:02 AM

    Ha, wow I’ve seen plenty of SAR images from MUCH more expensive systems that don’t look nearly as good. Incredible stuff here.

  • by throwup238 on 2/17/25, 2:21 AM

    This is why I read HackerNews.

    Every month there’s a new article that improves my suburban missile defense system* and helps guarantee that my neighbors will never let their dogs poop on my lawn ever again.

    Terrain mapping my neighborhood so that my rockets can navigate to the right offender has always been a challenge. Now I can just use drones!

    * It’s a defense system with missiles, not a defense system against missiles. That would be silly.

  • by nodra on 2/17/25, 4:54 AM

    An upvote doesn’t do this justice. Just an amazing write up. Thank you.

  • by slicktux on 2/17/25, 5:43 AM

    What an amazing project! Great synthesis of skills to make such a cool project! I’m in awe!

  • by taylorportman on 2/17/25, 4:53 AM

    If you need a 100 meter antenna - could one be approximated using multiple drones in a coordinated 100 meter parabolic trajectory?

  • by sllabres on 2/17/25, 6:47 AM

    What a impressive project and great results! Thanks for sharing here on HN.

  • by anilakar on 2/17/25, 7:03 AM

    > A single-channel radar can only measure the distance to a target and is unable to detect the angle of the target.

    Probably in that specific use case yes, but we have had parabolic dishes and slotted waveguide apertures for a long time now...

  • by tomaskafka on 2/17/25, 5:18 PM

    So, this will be seeing Russians even during the night and behind the trees?

    (And soon, the Chinese drones on attack through European cities will be able to hunt civilians 24/7?)

  • by willtemperley on 2/17/25, 7:13 AM

    This is incredible. Having had the misfortune of trying to get Sentinel 1 toolbox working, I'm now convinced it can be rewritten from scratch.

  • by transistor-man on 2/17/25, 2:57 AM

    Stellar work! This is such a wonderful writeup!

  • by cruftbox on 2/17/25, 6:10 PM

    Incredible engineering. Thanks for sharing it.