Satellite beam steering reference using terrestrial beam steering terminals

In a satellite communication system comprising at least one satellite having an antenna that generates a moving beam pattern on the surface of the earth, the beam pattern being comprised of a plurality of sub-beams, a satellite attitude correction system comprising:

• at least one reference transmitter at a known location on the surface of the earth;
• means for transmitting at least one signal from the at least reference transmitter into at least one of the sub-beams;
• means for receiving the at least one signal from the satellite antenna and for transponding the received at least one signal to a ground station;
• means for receiving the transponded at least one signal with the ground station;
• means for determining a gain of the received at least one signal and for comparing the determined gain to a gain expected to be received based on a predetermined knowledge of a spatial variation in gain of the satellite antenna;
• and
• means for determining a difference between the determined gain and the expected gain to derive a correction signal indicative of an attitude error of the satellite.

In a satellite communication system comprising at least one satellite having a steerable antenna that generates a moving beam pattern on the surface of the earth, the beam pattern being comprised of a plurality of sub-beams, a method for determining an antenna pointing correction signal for the satellite comprising the steps of:

• providing at least one reference transmitter at a known location on the surface of the earth;
• transmitting at least one signal from the at least reference transmitter into at least one of the sub-beams;
• receiving the at least one signal with the satellite antenna and transponding the received at least one signal to a ground station;
• receiving the transponded at least one signal with the ground station;
• determining a gain of the received at least one signal;
• comparing the determined gain to a gain expected to be received based on a predetermined knowledge of a spatial variation in gain of the satellite antenna;
• and
• determining a difference between the determined gain and the expected gain to derive a correction signal indicative of a pointing error of the satellite antenna.

In a satellite communication system comprising at least one satellite having an antenna that generates a moving beam pattern on the surface of the earth, the beam pattern being comprised of a plurality of sub-beams, a method for determining beam pattern correction signal for the satellite comprising the steps of:

• providing at least one reference transmitter at a known location on the surface of the earth;
• transmitting at least one signal from the at least reference transmitter into at least one of the sub-beams;
• receiving the at least one signal with the satellite antenna;
• comparing a gain of the received at least one signal to a gain expected to be received based on a predetermined knowledge of a spatial variation in gain of the satellite antenna;
• and
• determining a beam pattern correction signal in accordance with a difference between the actual gain and the expected gain.

In a satellite communication system comprising at least one satellite having an antenna that generates a moving beam pattern on the surface of the earth, the beam pattern being comprised of a plurality of sub-beams, a method for determining beam pattern correction signal for the satellite comprising the steps of:

• providing at least one reference transmitter at a known location on the surface of the earth;
• transmitting at least one signal from the at least reference transmitter into at least one of the sub-beams;
• receiving the at least one signal with the satellite antenna;
• comparing a gain of the received at least one signal to a gain expected to be received based on a predetermined knowledge of a spatial variation in gain of the satellite antenna;
• determining a beam pattern correction signal in accordance with a difference between the actual gain and the expected gain;
• and
• correcting the beam pattern in accordance with the correction signal and in accordance with information obtained from at least one attitude sensor means carried by said satellite.

In a satellite communication system comprising at least one satellite having an antenna that generates a moving beam pattern on the surface of the earth, the beam pattern being comprised of a plurality of sub-beams, a method for determining beam pattern correction signal for the satellite comprising the steps of:

• providing at least one transmitter at a location on the surface of the earth;
• transmitting at least one signal from the at least transmitter into at least one of the sub-beams using a predetermined access technique;
• receiving the at least one signal with the satellite antenna;
• comparing a gain of the received at least one signal to a gain expected to be received based on a predetermined knowledge of a spatial variation in gain of the satellite antenna;
• and
• determining a beam pattern correction signal in accordance with a difference between the actual gain and the expected gain.