The invention relates to methods and devices for precise geolocation of low-power, broadband, amplitude-modulated rf and microwave signals having poor coherency. The invention provides a basis for dramatic improvements in RF receiver technology, offering much higher sensitivity, very strong rejection of unintended signals, and novel direction finding techniques. When mounted on an airborne surveillance platform, the invention can detect and geolocate weak, broadband, incoherent RF and/or microwave signals. Embodiments of the invention are implemented by dual channel receivers (heterodyne or tuned-RF) that use crystal detection and Fast Fourier Transform (FFT) analysis for geolocation. Geolocation is accomplished using a subsystem of phased arrays and an angle of arrival technique.