Passive distance measurement using spectral phase gradients

Abstract From the Canadian patent

General method for extracting source distance information from any kind of received radiation, including electromagnetic and acoustic without involving , round-trip time or phase in any form and thus more truly passive than , existing passive radars. The method exploits the facts that radiation from a real source must comprise wavepackets of nonzero bandwidth that the , individual frequency components of a wavepacket must have consistent phase at the source, and that their instantaneous phases must increase linearly along the path in proportion to the respective frequencies so that the phase , gradient across the components must be proportional to the distance travelled. The invention …