Satellite communications system and apparatus
First Claim
1. An earth satellite communications system for transmitting data from a plurality of users through a repeating geostationary satellite to a plurality of receiving earth stations, comprisingA central transmitting station receiving data from a plurality of users, said station includingmeans for converting the format of said data into a form suitable for transmission to a satellite,means for spread spectrum processing the converted data, andmeans for transmitting the spread spectrum processed converted data to a repeating geostationary satellite, andA plurality of receiving earth stations, each of said receiving earth stations including .[.wide beamwidth, low gain.]. antenna means, said antenna means including a .Iadd.small, in the sense that a dish antenna with a diameter substantially less than 16 feet operating at 4 GHz in a system if which the orbital spacing of the geostationary satellites is 4 degrees is small, and consequently relatively wide beamwidth and concomitant low-gain .Iaddend.fixed directional antenna .[.having a beamwidth wider than the standard orbital spacing of geostationary satellites, whereby said antenna receives signals from more than one geostationary satellite,.]. .Iadd.having, at its operating frequency, a directional radiation pattern, in the sense that a 2 foot dish operating at 4 GHz has a directional radiation pattern, the beamwidth and gain of which pattern depends on the operating frequency and the antenna size, .Iaddend.anddetection means coupled to said antenna means,said detection means including spread spectrum processing .[.means,.]. .Iadd.means .Iaddend.for recovering data sent to said receiving earth station via said repeating geostationary .[.satellite.]. .Iadd.satellite even if and when the low gain and wide beamwidth of the antenna, resulting from its small size, leads to the reception of signals from said repeating geostationary satellite along with interfering signals from at least one other geostationary satellite, said spread spectrum processing means having a processing gain sufficient to substantially suppress said interfering signal.Iaddend..
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Reexamination
Accused Products
Abstract
A satellite communication system, which is inherently power limited, employing spread spectrum techniques in order to trade-off bandwidth for small ground station antennas. In a one-way system embodiment a central station transmits data to a satellite for relay to a large number of small antenna receiving stations, the transmissions being spread spectrum encoded with spreading code lengths selected to provide adequate data recovery at the least sensitive station to which the transmissions are directed. Spreading codes may also function to address particular stations. In a two-way system embodiment, the central station additionally functions as a terrestrial relay station. A plurality of small antenna transmitting stations, at least one of which may be at the same site as a receiving station, transmit code division multiplexed data via the satellite to the central relay station using sufficiently long and distinct spreading codes as to permit adequate data error rates and to distinguish the transmissions of the various stations. The central relay station reformats the received data for retransmission to the satellite for relay to the receiving stations.
123 Citations
22 Claims
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1. An earth satellite communications system for transmitting data from a plurality of users through a repeating geostationary satellite to a plurality of receiving earth stations, comprising
A central transmitting station receiving data from a plurality of users, said station including means for converting the format of said data into a form suitable for transmission to a satellite, means for spread spectrum processing the converted data, and means for transmitting the spread spectrum processed converted data to a repeating geostationary satellite, and A plurality of receiving earth stations, each of said receiving earth stations including .[.wide beamwidth, low gain.]. antenna means, said antenna means including a .Iadd.small, in the sense that a dish antenna with a diameter substantially less than 16 feet operating at 4 GHz in a system if which the orbital spacing of the geostationary satellites is 4 degrees is small, and consequently relatively wide beamwidth and concomitant low-gain .Iaddend.fixed directional antenna .[.having a beamwidth wider than the standard orbital spacing of geostationary satellites, whereby said antenna receives signals from more than one geostationary satellite,.]. .Iadd.having, at its operating frequency, a directional radiation pattern, in the sense that a 2 foot dish operating at 4 GHz has a directional radiation pattern, the beamwidth and gain of which pattern depends on the operating frequency and the antenna size, .Iaddend.and detection means coupled to said antenna means, said detection means including spread spectrum processing .[.means,.]. .Iadd.means .Iaddend.for recovering data sent to said receiving earth station via said repeating geostationary .[.satellite.]. .Iadd.satellite even if and when the low gain and wide beamwidth of the antenna, resulting from its small size, leads to the reception of signals from said repeating geostationary satellite along with interfering signals from at least one other geostationary satellite, said spread spectrum processing means having a processing gain sufficient to substantially suppress said interfering signal.Iaddend..
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10. In a geostationary earth satellite communications system, wherein the signals relayed from a repeating geostationary satellite are power limited spread spectrum signals, a receiving earth station comprising
.[.wide beamwidth, low gain.]. antenna means, said antenna means including a .Iadd.small, in the sense that a dish antenna with a diameter substantially less than 16 feet operating at 4 GHz in a system in which the orbital spacing of the geostationary satellites is 4 degrees is small, and consequently relatively wide beamwidth and concomitant low-gain .Iaddend.fixed directional antenna .[.having a beamwidth wider than the standard orbital spacing of geostationary satellites, whereby said antenna receives signals from more than one geostationary satellite,.]. .Iadd.having, at its operating frequency, a directional radiation pattern, in the sense that a 2 foot dish operating at 4 GHz has a directional radiation pattern, the beamwidth and gain of which pattern depends on the operating frequency and the antenna size, .Iaddend.and detection means coupled to said antenna means, said detection means including spread spectrum processing .[.means,.]. .Iadd.means .Iaddend.for recovering data sent to said receiving earth station via said repeating geostationary .[.satellite.]. .Iadd.satellite even if and when the low gain and wide beamwidth of the antenna, resulting from its small size, leads to the reception of signals from said repeating geostationary satellite along with interfering signals from at least one other geostationary satellite, said spread spectrum processing means having a processing gain sufficient to substantially suppress said interfering signals.Iaddend..
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15. An earth satellite communications system wherein a plurality of stations transmit data through a repeating geostationary satellite and a terrestrial relay station to a plurality of receiving earth stations, the combination comprising
a plurality of transmitting stations, each comprising means receiving data for transmission to a repeating geostationary satellite, means for spread spectrum processing said data, and means for transmitting said spread spectrum processed data to said repeating geostationary satellite, said transmitting means including .[.wide beamwidth, low gain.]. antenna means, .Iadd.said antenna means including a small, in the sense that a dish antenna with a diameter in the order of 4 feet opeerating at 6 GHz in a system in which the orbital spacing of the geostationary satellites is 4 degrees is small, and consequently relatively wide beamwidth and concomitant low-gain antenna, the beamwidth and gain of which pattern depends on the operating frequency and the antenna size, .Iaddend.and a terrestrial relay station, comprising antenna means, detection means coupled to said antenna means, said detection means including spread spectrum processing means for recovering data sent by said transmitting station, means for spread spectrum processing the recovered data, and means for transmitting the spread spectrum processed data to said repeating geostationary satellite, and a plurality of receiving earth stations, each of said receiving earth stations comprising .[.wide beamwidth, low gain.]. antenna means, said antenna means including a .Iadd.small, in the sense that a dish antenna with a diameter substantially less than 16 feet operating at 4 GHz in a system in which the orbital spacing of the geostationary satellites is 4 degrees is small, and consequently relatively wide beamwidth and concomitant low-gain .Iaddend.fixed directional antenna .[.having a beamwidth wider than the standard orbital spacing of geostationary satellites, whereby said antenna receives signals from more than one geostationary satellite,.]. .Iadd.having, at its operating frequency, a directional radiation pattern, in the sense that a 2 foot dish operating at 4 GHz has a directional radiation pattern, the beamwidth and gain of which pattern depends on the operating frequency and the antenna size, .Iaddend.and detection means coupled to said antenna means, said detection means including spread spectrum processing .[.means,.]. .Iadd.means .Iaddend.for recovering data sent to said receiving earth station via said repeating geostationary .[.satellite.]. .Iadd.satellite even if and when the low gain and wide beamwidth of the antenna, resulting from its small size, leads to the reception of signals from said repeating geostationary satellite along with interfering signals from at least one other geostationary satellite, said spread spectrum processing means having a processing gain sufficient to substantially suppress said interfering signals.Iaddend..
Specification