I'm not saying it's impossible, just perhaps impractical. It's amazing what you can do with EM if you have the processing power.

I remember seeing a coloquium by an ionospheric physicist who was using interferometry of FM radiostations to probe the fine structure of the ionosphere. It worked all right, better than he could've hoped Turns out, he could also watch planes fly around in realtime just like radar.

The rub is, FM is that part of the spectrum between where radar stealth and thermal IR obscurement are effective. Needles to say, he was visited by some DOD-MIB types who wanted to give him lots of money.