Distance between two radio frequency devices is estimated by receiving a plurality of spread spectrum chirp signals frequency offset from one another, and evaluating the received plurality of spread spectrum chirp signals for relative phase shifts between the plurality of spread spectrum chirp signals. A fine propagation time is derived using the phase shifts between the spread spectrum chirp signals. A frequency domain despreading window is shifted to reduce the influence of time-delayed near multipath signals in receiving the plurality of spread spectrum chirp signals.