I showed your comment to the 20 year old drone detection experts in Ukraine and they laughed at your dismissal, I imagine these guys know a lot more about FPGAs (slide 12 and further of [1]) then you, their lives depend on it every day.

Actual passive radar as we do in the Ukraine kill zones is very difficult science because all radio sources move all the time and the entire environment is full of reflections of moving leaves, nets, etc. Plus multiple moving antennas and jammers.

But then the rewards are big too. At the moment 80% of Russian casualties are from fiber optic FPV or cheaper radio controlled FPV drones only. So if we get even a little passive radar working (mainly by better over the network nanosecond time calibration [1] and orders of magnitude cheaper software defined radio receivers scattered densely on the ground plus cheap decoy transmitters and jammers) we save hundreds of thousands of lives, even tip the balance in winning this war.

Key is the orders of magnitude more complex calculations we do, hence the need for cheap supercomputers (cheaper than NVDIA). The first supercomputer I sold in 1986 to a Phd working on radar at Holland Signaal, the military brach of Philips.

[1] White Rabbit - High precision clock distribution in modern astroparticle experiments https://indico.kit.edu/event/22/contributions/927/attachment...

[2] New timing system for the LOFAR2.0 telescope https://videos.cern.ch/record/3015600

[3] Rocket Science is no rocket science if you get my thrust https://theconversation.com/rocket-science-isnt-rocket-scien...

p.s. Btw, rocket science [3] is the wrong term because that is actually really not very hard science at all, never was. "Elon Musk set back space travel 50 years" - Alan Kay. (He means rocket science is the wrong science for space travel, you need much better propulsion than chemical rockets because of the Tsiolkovsky rocket equation.