Radar Models and MTI

There were various types radar and radar equipment that controllers had to be aware of.  These various radars could also work on four types of scans.  These included PPI (Plan Position Indicator), HRI (Height Range Indicator), “A” (a testing scan), and “B” (which had long, medium, and short ranges).  There are numerous models of radar, but in the late 1950s the main types of ground radar that a controller needed to know were as follows:

AN/CPS 6 B (Army, Navy-Air Transportable Radar, Detection, Range, and Bearing)

This type of radar was used in Ground Control Interception, or GCI and reached about 200 nautical miles (about 120 when running the Moving Target Indicator, or MTI) and 40, 000 feet.  It could find and track a mid-sized bomber at this distance, and even further if there were many. 

It ran all four types of scans.

AN/FPS 3 C (Army, Navy- Fixed, Radar, Detection/Range and Bearing, Canadian)

The AN/FPS 3 C was an early warning radar used in conjunction with height finders (TPS 501/502 or FPS 6) for GCI.

It ran both PPI and "A" scans and could reach 50, 000 feet, covering 400 nautical miles (200 when it used MTI).

AN/FPS 6 (Army, Navy-Fixed Radar, Detection, Range and Bearing)

The AN/FPS 6 was a height finder radar used along with a search radar.  It could reach 200 nautical miles and 60, 000 feet. 

It used the HRI scan.

AN/TPS 501/502 (Army, Navy-Tactical Transportable Radar, Detection, Range and Bearing)

The AN/TPS 502 was a height finding radar of the tilting antenna variety.  It could reach up to 60 000 feet and 120 nautical miles for bombers, and 60 miles for fighters, and could see 360 degrees.  It was used along with a search radar like the AN/FPS 3.

The AN/TPS 501 was a previous version that only differed in range.

Moving Target Indicator:

The Moving Target Indicator, or MTI, used the Doppler principle and helped see past the echoes created from stationary objects such as buildings.  It was also used to help counter-act jamming.