Minitrack

Minitrack was developed around 1955 in the U.S. radio system to monitor ballistic missile launches and later also for approximate orbit determination for satellite launches.

It worked on the principle of interference and used the 108 MHz frequency of U.S. satellites for current direction measurements to the missiles. Eight antennas were arranged in pairs at different distances in the four directions: the two antenna pairs in 7 and 55 wavelengths ( about 20 and 152 meters), in north-south direction in addition 3.7 m ( 1.318 λ ). This elevation angle and meridian passages were better than ± 0.05 degrees measured.

The first mini- track system was built in Blossom Point, Maryland and went in July 1956 in operation. For orbit determination of satellite measurements, however, were required by several receivers. In November 1957, the mini- track system included ten stations. Further stations were added later, others fell away again. End of the 1960s, the system was replaced by more accurate Funkmeßsysteme and partially expanded to special satellite stations.