2 RX signals and compare for radar

My project is develop a small radar using limesdr-usb. My ideia is using limesdr with 2 receivers channel and compare the signal (designated passive radar).
I’m new in limesdr, what’s suggestions do you have?

I’m using windows 10 and gnu radio.
What is the advantage to use Photos? Just the gnu radio with the libs of limesdr doesn’t work? Sincerely I tried a lot of times with gnu radio but none of that attempts was successful.