04463357 is referenced by 144 patents and cites 3 patents.

The columnar electron content of the ionosphere between a spacecraft (10) and a receiver (12, 14) is measured in realtime by cross correlating two coherently modulated signals transmitted at different frequencies (L.sub.1, L.sub.2) from the spacecraft to the receiver using a cross correlator (16). The time difference of arrival of the modulated signals is proportional to electron content of the ionosphere. A variable delay (21) is adjusted relative to a fixed delay (20) in the respective channels (L.sub.1, L.sub.2) to produce a maximum at the cross correlator output. The difference in delay required to produce this maximum is a measure of the columnar electron content of the ionosphere. A plurality of monitoring stations (31, 32, 33) and spacecrafts (GPS satellites 34, 35, 36) are employed to locate any terrestrial event that produces an ionospheric disturbance.

Title
Method and apparatus for calibrating the ionosphere and application to surveillance of geophysical events
Application Number
6/322317
Publication Number
4463357
Application Date
November 17, 1981
Publication Date
July 31, 1984
Inventor
Peter F MacDoran
Pasadena
CA, US
Agent
John R Manning
Thomas H Jones
Paul F McCaul
Assignee
The United States of America represented by the Administrator of the National Aeronautics and Space Administration
DC, US
IPC
G01S 3/02
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