Direction finding and mapping in multipath environments

A method for determining a direction of a direct arrival path between a receiver and a transmitter and mapping a path traversed by the receiver in a multipath environment wherein a received signal at the receiver includes a direct path signal component of a transmitted signal and a plurality of multipath signal components of the transmitted signal and wherein the transmitter is in motion. comprising the steps of:

• identifying in the received signal
• a doppler pedestal comprised of a plurality of multipath signal components having a range of doppler shifts, each multipath doppler shift being determined by a relative motion between a scatterer and at least one of the transmitter and the receiver, and
• a direct path signal component. and
• determining at least one of
• a transmitter heading relative to the receiver as proportional to a frequency offset of the direct path signal component relative to the multipath pedestal. and
• an absolute velocity of the transmitter as proportional to a width of the multipath pedestal,
• recording successive transmitter headings relative to the receiver and absolute velocities of the transmitter over a sequence of intervals during which the transmitter traverses a path, and
• correlating the recorded transmitter headings and absolute velocities with corresponding geographical locations along the path to generate a map of the geographic map expressed in transmitter headings and absolute velocities.

A method for determining a direction of a direct arrival path between a receiver and a transmitter and determining a geographic a path traversed by the receiver in a multipath environment wherein a received signal at the receiver includes a direct path signal component of a transmitted signal and a plurality of multipath signal components of the transmitted signal and wherein the transmitter is in motion, comprising the steps of:

• identifying in the received signal
• a doppler pedestal comprised of a plurality of multipath signal components having a range of doppler shifts, each multipath doppler shift being determined by a relative motion between a scatterer and at least one of the transmitter and the receiver, and
• a direct path signal component, and
• determining at least one of
• a transmitter heading relative to the receiver as proportional to a frequency offset of the direct path signal component relative to the multipath pedestal, and
• an absolute velocity of the transmitter as proportional to a width of the multipath pedestal,
• determining successive transmitter headings relative to the receiver and absolute velocities of the transmitter over a sequence of intervals during which the transmitter traverses a path, and
• correlating the determined transmitter headings and absolute velocities with at least one stored path map representing corresponding geographical locations along a path expressed in transmitter headings and absolute velocities.