Nike-Ajax was an American, radar-guided, surface-to-air missile. The control sites had radar that could follow the missile and used plotting and computers to process this information.
The specific radar equipment used included an ACQR, or Acquisition Radar. The ACQR found the target and then passed this information on to the TTR, or Target-Tracking Radar.
There was also an MTR, or Missile-Tracking Radar for the missile itself. All the information from these radars was then compared electronically and the directions to intercept were given.
In 1953, before Nike-Ajax was put to use, a new Nike missile was created. The Nike-B, or Nike-Hercules (MIM-14 A/B) was more advanced than the Ajax and had a further range. It also took over the control sites the Ajax had used (though it did not require as many, so some were shut down).
The Nike-Hercules used some of the same radar as the Nike-Ajax but was updated. It also included an extra TTR.
In its test flight in 1955, the Hercules flew at Mach 3, as high as 100 000 feet and had a range of seventy-five miles (later ninety). This was all far above expectations.
The United States Army updated the program in the 1960s, adding an expensive but advanced High Power Acquisitions Radar, HIPAR. Many of the control sites also took on AN/FPS-60, AN/FPS-71, or AN/FPS 75, Alternate Battery Acquisition Radars. The radar that had been used for this purpose previously on the Hercules, became the Low-Power Acquisition Radar, or LOPAR.
The Army removed itself from air defence and the command in 1975 and stopped using Nike-Hercules.