History of Radar Tracking

Cursor position Range 026.7 km | Azimuth 042.8"

History of Radar Tracking

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Fig. 1. PPI radar display showing targets and clutter.

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In the early days of radar, range and angle-tracking functions were performed manually. Using a device such as a track ball, the operator could keep the cross-hairs positioned on the range and azimuth angle of a detected target viewed on a display such as a plan position indicator (PPI) display. The PPI display, such as that shown in Fig. 1, provides a two-dimensional display of range and azimuth angle for a radar with an azimuth-scanning antenna. Targets result in blips on the display where the brightness (and size) of the blips are related to
the amplitude of the target echoes at the receiver. The output of the track ball can provide readout of the target range and azimuth angle or provide the required range and angle information to weapons systems for targeting purposes. Although this was a satisfactory technique for tracking slow-moving targets such as ships, it is certainly a tedious process.

To aid in the tracking of ships and aircraft, a rate-aided device was added to some systems. With rate – aided tracking, the operator needed to make only fine adjustments to account for changes of the target range and angle rates with respect to the radar. With this configuration, the radar operators were better able to track faster-moving objects such as aircraft. Still, this tracking function required the constant attention of the radar operator.

Automated target tracking evolved as a necessary tool to allow the radar operator to perform the tracking function efficiently. After range and angle trackers are locked onto the target, the tracker then senses any error between the current target position and that predicted by the tracker and automatically and contin­uously adjusts the tracker functions either on a pulse-to-pulse or scan-to-scan basis. As a result, automatic radar tracking can maintain target track more accurately than a human operator and can better follow fast maneuvering targets.

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