US 5,926,758 AGranted

Radio frequency sharing methods for satellite systems

AssigneeLeo One IP, L.L.C.

InventorsDavid P. Grybos, James M. Marshall

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Abstract

Methods and apparatus are disclosed which allow many satellites (A1-M, B1-N) in a plurality of Systems (A, B) to use the same radio frequencies (f1-n) so long as there is no interference between radio signals. The methods compute times (t) when satellite radio signals (32, 36) have overlapping reception areas or "footprints" (30, 35) on the Earth's surface (E) whereby a user's reception or transmission of a message would be interfered unless different frequencies (f1-n) are used for the "competing" signals. The methods use a timing algorithm that does not allow two satellites (Ai, Bi) which are "visible" at the same point on the Earth (E) to transmit on the same frequency (fi). In one preferred embodiment, a timing algorithm (48) produces a radio frequency use schedule (49) computed on the Earth from orbital data maintained in an ephemeris (46) of satellite communications systems (A, B) which communicate on frequencies (f1-n) giving rise to interfering radio signals. The radio frequency use schedule (49) is updated frequently, and is transmitted to and stored on board each satellite in System A (A1-M). System A satellites (A1-M) are then operated in accordance with the radio frequency use schedule (49).

Claims11

Dependent claims

A method of radio frequency sharing between satellites (A1-M) in a first System (A) and satellites (B1-N) in a second System (B), said satellites of said first System (A) being in communication with Earth (E) through a plurality of ground relay stations (18) and user terminals (20), said first System (A) having a plurality of orbit planes (14, 15) containing said satellites (A1-M), the method comprising the steps of:

assigning an initial communication frequency to all said satellites (A1-M) in each one of said plurality of orbit planes (14, 15) of said first System (A);
said initial communication frequency being identical for all satellites (A1-M) residing in a same orbital plane (14, 15);
changing said initial communication frequency (f.sub.Ai) assigned to one of said satellites (Ai) residing in a first one of said orbital planes (14) of said first System (A), to a frequency (f.sub.Aj) assigned to satellites (Aj) residing in a second one of said orbital planes (15) of said first System (A), when a radio beam footprint (30) of said satellite (Ai) overlaps a radio beam footprint (35) of one of said satellites (B1-N ) residing in said second System (B) and said radio frequencies being in use by respective said satellites (A1-M, B1-N) will interfere;
said frequency (f.sub.Aj) being one which does not interfere with any other satellite (A1-M) in said first System (A) or a satellite (B1-N) in said second System (B), and
effecting timing of said changing said initial communication frequency (f.sub.Ai) by using a radio frequency use schedule (49) computed in advance from orbital parameter ephemeris data (46) for said satellites (A1-M) in said first System (A) and satellites (B1-N) in said second System (B).

2 more elements

Dependencies are inferred from the claim text.