High latitude geostationary satellite system

A high latitude communications satellite system comprising:

• a plurality of satellites disposed to move in respective elliptical orbits, each said orbit being defined by an identical inclination value and defining from a terrestrial observation point a first pair of loops comprising a first minor loop and a first major loop disposed at a first longitudinal position, and a second pair of loops comprising a second minor loop and second major loop disposed at a second longitudinal position, said first pair of loops being separated from said corresponding second pair of loops by 180° longitude, and being at the same latitude positions, and both said first pair of loops and said second pair of loops being wholly disposed in one of the northern and southern hemispheres at a minimum angular separation from geostationary orbit of not less than 45°;
• and
• a plurality of ground-based, directive, tracking and non-tracking narrow beam antennas, each operative to provide pointing to and communications with each of said satellites while each of said satellites is in a portion of the first or second minor loops;
• wherein a first satellite which is exiting one of said minor loops will be substantially co-located with a second satellite which is concurrently entering said one minor loop,
• wherein said first satellite exiting said minor loop has been in communication with at least one of said ground-based antennas during at least a portion of time said first satellite is in said minor loop, and said satellite entering said minor loop will be in communication with said same at least one ground-based antenna, and
• wherein communication from said first satellite to said ground antennas station is transferred to said second satellite, the timing of said transfer being established on board said satellites using timing provided directly to said first and second satellites by a GPS satellite in a constellation of GPS satellites.

A high latitude communications satellite system comprising:

• a plurality of satellites disposed to move in respective elliptical orbits, each said orbit being defined by an identical inclination value and defining from a terrestrial observation point a first pair of loops comprising a first minor loop and a first major loop disposed at a first longitudinal position, and a second pair of loops comprising a second minor loop and second major loop disposed at a second longitudinal position, said first pair of loops being separated from said corresponding second pair of loops by 180° longitude, and being at the same latitude positions, and both said first pair of loops and said second pair of loops being wholly disposed in one of the northern and southern hemispheres at a minimum angular separation from geostationary orbit of not less than 45°;
• and
• a plurality of ground-based, directive, tracking and non-tracking narrow beam antennas, each operative to provide pointing to and communications with each of said satellites while each of said satellites is in a portion of the first or second minor loops;
• wherein each of said plurality of satellites comprises a phased array antenna operative to change said satellite's overall beam pattern in response to commands based on the location of said satellite in orbit.

A high latitude communications satellite system comprising:

• a plurality of satellites disposed to move in respective elliptical orbits, each said orbit being defined by an identical inclination value and defining from a terrestrial observation point a first pair of loops comprising a first minor loop and a first major loop disposed at a first longitudinal position, and a second pair of loops comprising a second minor loop and second major loop disposed at a second longitudinal position, said first pair of loops being separated from said corresponding second pair of loops by 180° longitude, and being at the same latitude positions, and both said first pair of loops and said second pair of loops being wholly disposed in one of the northern and southern hemispheres at a minimum angular separation from geostationary orbit of not less than 45°;and
• a plurality of ground-based, directive, tracking and non-tracking narrow beam antennas, each operative to provide pointing to and communications with each of said satellites while each of said satellites is in a portion of the first or second minor loops;
• wherein said satellites comprise 3-axis stabilized mechanisms and single gimbaled solar arrays, further comprising:
• means for removing the rotation of the satellite antenna about the target point in order to avoid rotation of the beam during the operational period while said satellite is in said minor loop.

A method of switching active communication links from a first one to a second one of a plurality of satellites disposed to move in respective orbits defined in separate planes, all of said orbits having a common inclination and defining to a terrestrial observer at a ground-based antenna location a common pair of apparent loops, comprising a minor loop and a major loop, said minor loop being defined between a maximum latitude of approximately 63.4° and a minimum latitude of greater than approximately 45° and at a predetermined angular separation from geostationary orbit, said communication links being defined between said satellites and a plurality of ground-based antenna operative to communicate with said satellites while they are in said minor loop, comprising:

• a) detecting and storing at each of said first and second satellites GPS timing information:
• b) transmitting from each of said first and second satellites and receiving at said second and first satellites, respective GPS timing information via an inter-satellite link when they are proximate within their elliptical orbit:
• c) detecting when the time difference between said GPS signals is a minimum:
• d) responsive to said time difference detecting step, commanding the activation of an inactive one of said satellite communication transmitters and the inactivation of a corresponding active one of said satellite communication transmitters, whereby switching of at least one active communication link from an active transponder on a first satellite to an activated transponder on a second satellites is obtained.