Passive radars are known already from WW2. Here I present my solution to use RTL-SDR dongle and fast Radeon video card (NVIDIA is also possible but the library are different). This software uses OpenCL libraries from Radeon (similar are also for NVIDIA). Program supports up to 2 coherent receivers but for passive radar one dongle is enough. I would like to thanks Frank from Finland for excellent idea and hard work!
x64 version of radar software can be downloaded from here.