Dual-frequency ranging at narrow separation frequencies as a method of reducing satellite ranging errors due to the ionosphere

The U. S. Navy Navigation Satellite System and the Geodetic SECOR satellite system both employ two widely separated carrier frequencies to permit an error correction to be made for ionospheric refraction. It is shown that this same two-frequency technique can be employed within the narrow bandwidth of a VHF communications satellite repeater to permit ranging signals transmitted through the repeater to be corrected for ionospheric refraction error.