Abstract: A short baseline navigation system employs the real-time estimation of the positions of multiple cooperative targets. Each target replies with a unique stepped frequency sequence signal that covers the usable frequency band. A processor operates on reply signals received by elements on the tracking platform and develops a coarse time-difference-of-arrival estimate using an algorithm derived herein. The processor also estimates the Doppler shift of received signals, and determines a time-window (or gating) that eliminates the portions of the received signals corrupted by multipath interference. The relative phase differences between the received signals are then used in conjunction with the coarse time-difference-of-arrival estimates for a precise direction-of-arrival estimation.