AN/TPS-25

I served in the 25th Infantry Division Artillery as a ground surveillance radar operator from 4/69 to 4/70. Our base camp was in Cu Chi, however, we were rarely there. Our 5-man team operated the AN/TPS-25 battlefield ground surveillance radar system primarily along the Cambodian border, near the Angel's Wing and Parrot's Beak, AO's (Area of Operation) of the 25th Infantry Division. These areas were major infiltration points along the Ho Chi Minh trail. Although we were attached to the 25th Infantry Division Artillery, we moved about independently, via helicopters or trucks, setting up the radar and tower at a dozen locations during my 12 month tour. These locations included Fire Support Bases (FSB's), Advanced Tactical Support Bases (ATSB's), Patrol Bases, ARVN Infantry camps, a couple of Special Forces camps and a 2 or 3 week stay at the base camp in Tay Ninh.

The TPS-25 radar had a maximum range of 11 miles (18 km) and incorporated doppler which allowed an experienced operator to identify the target by means of a characteristic audio return. Most targets were detected between 1/4 to

8 miles out. Range was usually limited by tree lines or other obstacles but we minimized this loss somewhat by mounting the radar dome on an 84 foot tower. Power for the radar was originally supplied by a one kilowatt generator but this proved to be marginal in performance and reliability and was eventually replaced by superior 3 kilowatt model.

We operated the radar mostly during the hours of darkness, 1800 to 0600 (6:00 PM to 6:00 AM). Each team member pulled 2 shifts on the radar per night. Shifts were usually performed solo unless it was a new replacement in-training. When a target was detected the operator would contact TOC (Tactical Operations Center) via 2-way scrambled (encoded, decoded) radio, and give the coordinates, description and direction of movement. TOC would order a fire mission (almost always artillery) on the target if it was determined to be hostile and was located in a fire zone. About 1/3 of our targets were fired upon. When a fire mission took place TOC would advise us the moment the artillery rounds were in the air. We could observe impact and call adjustments as necessary (and it was usually necessary).

Although our primary mission was to detect infiltration we often detected hostile movement near our own camp and gave the commander the advantage of early warning.

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