I want this, but I do not have the experience with radio signals to build this myself without more guidance. Is there a DIY proof of concept I could lean on? How much more challenging will this be if you are in an area with overlapping FM signals from 2 transmitters sending the same signal?
This is a very good point to start: https://www.rtl-sdr.com/tag/passive-radar/
If you have more than one receiver, the main issue is time sincronisation between the receivers.
Using the two transmitters will complicate things a lot
For this kind of thing you need to step up to the kraken.
You can start with the radar receiver data from this 7 part DIY radar course [1] from a guy who works at a company who sell the needed chips.
Halfway in the video he mentions the MIT (or Stanford) course of a professor who recently died. That course is online and has a lot of documentation (much better than this course.
Build Your Own Drone Tracking Radar: Part 1 https://www.youtube.com/watch?v=igrN_wd_g74&t=292s
You can contact me if you want more guidance. For passive radar you can just start with recorded data. I have access to huge amount of recordings on the Ukraine battlefield. Buying or building cheap antennas and radios is not needed for passive radar software development.
Radar was developed during the last two years of WOII, mainly in Boston at MIT and hundreds of companies each building a radar, most were deployed months later to win the war. Development after the war shifted to Silicon Valley, founding Silicon valley and the later chip and software startups decades later.
Would suggest to take a look at Jackson’s book on classical electrodynamics to get some intuition.
That's very evil to recommend a graduate electrodynamics book to learn more about passive radar. I would suggest taking a look at Platos Republic to get some intuition on why that is. </s>
If you want to make an apple pie from scratch, first you must invent the universe…
A famous quote from Carl Sagan in the marvelous Cosmos documentary where he explains atoms by slicing an apple pie until you can not slice no more because you are down to a single elementairy particle the atom.
Carl also references Plato's Republic when visiting the actual cave where Plato lived.
Carl also references books classical mechanics but not the book the parent comment mentions but earlier ones like Al-Baghdadi, Cristian Huygens, Galileo, Newton.