First responder location and tracking using Synthetic Aperture Navigation

The Synthetic Aperture Navigation (SAN) signal processing algorithm identifies the desired line of sight (LOS) signal component by exploiting user motion. As implied by the name, it forms a synthetic aperture along the user trajectory by taking multiple snapshots of signal correlation with the replica waveform over some period of time as the user moves. The synthetic aperture serves as an array, which enables beamforming with a single-element antenna. Fundamentally, this method discriminates between different signal components (e.g., line of sight and multipath) by their directions of arrival. SAN places the antenna array gain on the desired signal component and places nulls on all other components. This operation is applied to data from all correlators in the receiver, thus effectively providing the receiver discriminator with nearly multipath-free measurements. SAN is even able to produce a quality line of sight (LOS) measurement when the LOS component is much weaker than multipath.