Satellite personal communications system

• US 4,189,675 A
• Filed: 05/30/1978
• Issued: 02/19/1980
• Est. Priority Date: 05/30/1978
• Status: Expired due to Term

• Current Assignee: Frosch Robert A Administrator of The National Aeronautics and Space Administration With Respect To An Invention of, Joel G. Smith, Norman B. Reilly
• Original Assignee: Frosch Robert A Administrator of The National Aeronautics and Space Administration With Respect To An Invention of, Joel G. Smith, Norman B. Reilly
• Inventors: Frosch, Robert A. Administrator of the National Aeronautics and Space Administration, with respect to an invention of, Reilly, Norman B., Smith, Joel G.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Masinick, Michael A.
• Application Number:
  US05/910,707
• Time in Patent Office: 630 Days
• Field of Search: 325/4, 325/14, 325/5, 325/8, 325/9, 179/15 BS, 179/15 BY, 179/, 179/16 E, 343/100 SA
• US Class Current: 455/13.2
• CPC Class Codes: H04B 7/2041 Spot beam multiple access
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A communication system is described for providing voice channel communication between any of many thousands of moderate cost and low power mobile stations dispersed over a large area such as the continental United States, and which is especially useful for connecting users who are primarily stationed in rural areas that cannot be economically served by trunk dispatch mobile networks. The system includes a geostationary satellite utilizing a large UHF antenna that can receive a transmission from a caller and retransmit it over any one beam of a matrix of narrow beams, so the chosen beam covers an area in which a designated called party is located. A single up-link control channel occupying a narrow frequency band, can be utilized to receive dial up signals from a caller, and another single down-link control channel can be utilized to ring up the called party located anywhere within the continental United States. The satellite antenna includes a matrix of feed horns that not only direct the beams in a controlled matrix onto the area of the continental United States, but also permit detection of the region from which the caller'"'"'s signal is transmitted and the region from which the called party'"'"' s answer is received, to enable the interconnection of signals received from these two regions.

Claims

1. A communication system for establishing communication between a large number of earth based terminals by means of a satellite, using a limited radio frequency bandwidth, comprising:

a satellite which includes a large reflector, a plurality of signal ports for transmitting and receiving, and means for directing a narrow angle radio wave beam containing signals received from a signal port to one of a multiplicity of sectors on the earth by way of the reflector; and

a plurality of terminals located in different of said sectors of the earth;

said satellite including means for delivering signals containing the same radio frequency band to different ones of said ports, so that the same frequency band can be used in different sectors of the earth;

said satellite including means responsive to a signal received from a sector of the earth by one of said ports, for processing the signal and then delivering it to a port for retransmission to a particular sector of the earth;

each of said terminals is responsive to a different coded ring up signal; and

said satellite includes means responsive to a dial signal designating a particular called party, for delivering a corresponding ring up signal to all of said sectors of the earth.

2. The communication system described in claim 1 wherein:

said means for directing a narrow angle radio wave beam includes a matrix of feed horns positioned to direct signals to said large reflector, and a Butler matrix means connected to said ports and to said feed horns for applying signals of a controlled relative phase and amplitude to said horns in response to signals received from a particular port, to produce a narrow beam of predetermined direction from said reflector.

3. A communication system for establishing communications between a large number of earth based terminals by means of a satellite, comprising:

a satellite which includes a large reflector, an array of feed horns positioned to direct radio waves to and receive radio waves from said large reflector, a Butler matrix means coupled to said feed horns and having a plurality of signal ports, for applying signals of a controlled relative phase and amplitude to said horns corresponding to signals received in one of said ports to produce a narrow beam along a predetermined direction from said reflector, and for producing on a certain one of said ports an output signal originating from a particular location on the earth;

said satellite including means connected to said ports for demodulating the signal received from a first port, to obtain a limited signal lying in a channel of limited badwidth within said signal from said first port, and for combining said limited signal and other signals and delivering them to a predetermined one of said ports to produce a narrow beam for delivery to a particular sector of the earth;

said satellite also including means responsive to the particular horn from which an acknowledgement transmission is received from an earth based terminal, for selecting said predetermined one of said ports so it transmits to the same sector of the earth from which the acknowledgement transmission was received.

4. A method for establishing communication between any pair of a large number of earth based terminals by means of a satellite, comprising:

establishing in orbit a satellite with a large reflector and a plurality of signal processing means for receiving and transmitting radio waves, by reflection off the reflector, to and from primarily only a limited sector of the earth'"'"'s surface, and with the sectors overlapping to cover a predetermined wide area of the earth;

delivering each of a plurality of signals, wherein each signal lies within a predetermined frequency channel of signals received from a particular one of said signal processing means, through a switching means to a modulator means, operating said modulator means to generate a signal within another predetermined frequency channel, and delivering said signal from said modulator means through a predetermined signal processing means for delivering by way of said reflector to a particular sector of the earth;

detecting dial signals defining a called party and broadcasting to all of said sectors a call up signal which activates an indicator on the earth based terminal which is defined by said dial signal;

transmitting an acknowledgement signal from the called party;

detecting the sectors from which said dial signal and acknowledgement signal originated; and

operating said switching means to route signals in a particular frequency band that originate in the sector of the called party, so those signals are delivered by way of said modulator means and reflector to the sector of origination of the dial signal which defined that called party.