Sequential Collation of Range
Sequential Collation of Range ( SECOR ) is a microwave method for measuring distances over long distances by comparing phases .
The method was developed around 1960 for satellite geodesy and was first used in the ANNA 1B flashlight satellite launched at the end of 1962 . It measures the distance between the ground station and the satellite by responding to the measurement impulses with a transponder . The phase difference between the signals is a measure of the distance. The ambiguity is resolved by using four very different frequencies, similar to the tellurometer developed at the time for terrestrial EDM.
A total of 14 small satellites were launched for the SECOR system, 10 of which successfully reached earth orbit. These satellites were also designated with the name SECOR or alternatively with EGRS ( Electronic & Geodetic Ranging Satellite ).
The measuring accuracy of 1–3 meters was a top value for the 1960s , but the construction of the ground stations was relatively complex (measuring hut, medium-sized roof antenna, control). That is why they were gradually shut down after successfully completing the SECOR Equatorial Network , which was the first survey network to span the entire earth. A few years later, satellite lasers (see Satellite Laser Ranging SLR) were able to achieve even better accuracy, which today is even in the millimeter range.
Web links
- SECOR satellite (prototype) at skyrocket.de
- SECOR satellite (series version ) at skyrocket.de