Velocity measurement using angular- and frequency-correlation techniques

Detecting and estimating the velocity of slowly moving targets from a moving platform is difficult due to the Doppler broadening of the ground clutter. The latest MTI (moving target indicator) technique employs STAP (space time adaptive processing) to reduce the clutter's signal and thus is able to detect the target's speed. This technique has proven to be very effective for detecting high-speed targets and also for some slower moving targets such as helicopters. If, however, the target's speed is small, such as ground targets, the target's signal is reduced along with the clutter, again rendering the detection of the target's speed difficult. The techniques described in this paper utilize the signals from a multiple sensor system and are based on the correlation of the scattered waves of the target. The Doppler shift of the correlation function is then used to obtain the target's velocity. Unlike conventional MTI radar, our technique makes use of the Doppler shifted phase of the correlation of the scattered waves. Controlled experiments were conducted with an X-band radar and good agreement was obtained with numerical simulations.