Satellite system using equatorial and polar orbit relays

• US 5,678,175 A
• Filed: 06/06/1995
• Issued: 10/14/1997
• Est. Priority Date: 03/28/1994
• Status: Expired due to Fees

• Current Assignee: Leo One IP, LLC
• Original Assignee: Leo One IP, LLC
• Inventors: Smith, Steven W., Peters, Arthur K., Villalvazo, Jose Manuel, Goldman, Erik J., Bayer, David A., Sturza, Mark Alan, Stuart, James R.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): BANKS HAROLD, MARSHA DENISE
• Application Number:
  US08/466,176
• Time in Patent Office: 861 Days
• Field of Search: 455/11.1, 455/12.01, 455/13.1, 455/13.3, 455/13.4, 455/33.1, 455/33.2, 455/54.1, 455/53.1, 455/56.1, 342/352, 342/356, 342/357, 342/387, 342/457, 370/75, 370/79, 370/84, 370/94.1, 370/94.2, 370/95.1, 370/95.3, 370/97, 370/104.1, 348/12, 348/13
• US Class Current: 455/13.1
• CPC Class Codes: H04B 7/18521 Systems of inter linked satellites, i.e. inter satellite service for optical links between satellites H04B10/118
• CPC Class Codes: H04B 7/195 Non-synchronous stations

Abstract

A satellite communications system is disclosed. One of the embodiments of the present invention includes six to fourteen satellites (12) which operate in a single Equatorial orbit (14). These satellites (12) are capable of providing communications services to locations on the Earth (E) which are within thirty degrees of the Equator (16). Another embodiment of the invention utilizes both the single Equatorial orbit plane (14) in combination with other satellites (12) moving in polar or inclined orbits (60, 63, 210). The embodiment that combines satellites (12) in Equatorial (14), polar (60) and inclined (63, 210) orbits will provide a wide variety of data services to virtually any point on the globe. In the preferred embodiments, the satellites (12) are designed to operate in a circular low Earth orbit at an altitude of from 800 to 1852 kilometers. Although the preferred embodiments utilize this specific range of altitudes, the satellites (12) are designed to fly in any orbit that is not a geosynchronous orbit. The satellites (12) are also capable of speeding packetized messages (225) around the globe either by working in combination with relay stations (34, 61, 65) on the ground, by transferring message payloads (225) across different orbits via the relay stations (34, 61, 65) or by conveying packetized payloads (225) through the use of inter-satellite links (55).

Claims

1. A satellite communications system comprising:

a plurality of Equatorial, polar and middle latitude relay stations (34, 61,

     65);

said relay stations (34, 61,

     65) being located circumferentially along Earth'"'"'s Equator (16), near Earth'"'"'s poles (NP, SP) and in regions of Earth'"'"'s middle-latitudes, respectively;

a first satellite (12) operating in an Equatorial, low Earth orbit (14);

a second satellite (12) operating in an inclined, low Earth orbit (60, 63,

     210);

said first satellite (12) being capable of communicating with said plurality of Equatorial relay stations (34) over uplinks (35a) and downlinks (35b);

said second satellite (12) being capable of communicating with at least one of said plurality of polar relay stations (61) with at least one of said plurality of middle-latitude relay stations (65) and with at least one of said plurality of Equatorial relay stations (34);

said first satellite (12) being capable of storing a message from a first Equatorial relay station (34) and forwarding said message to a second Equatorial relay station (34); and

said second satellite (12) capable of receiving said message from said second Equatorial relay station (34) and forwarding said message to one of said plurality of polar and middle-latitude relay stations (61,

     65).

2. The satellite communications system as claimed in claim 1 further including a plurality of satellites (12) operating in said Equatorial and inclined orbits (14, 60, 63, 210);

said plurality of satellites (12) operating in said Equatorial orbit (14) being capable of communicating over inter-satellite links (55).

3. The satellite communications system as claimed in claim 2 in which said plurality of satellites (12) includes at least six satellites (12), equally spaced in said Equatorial orbit (14).

4. The satellite communications system as claimed in claim 2 in which said plurality of satellites (12) includes a maximum of fourteen satellites (12), equally spaced in said Equatorial orbit (14).

5. The satellite communications system as claimed in claim 2 in which each said plurality of satellites (12) is capable of communicating over a generally circular area (44), between a latitude on the Earth (E) of thirty degrees North (18) and a latitude on the Earth (E) of thirty degrees South (20).

6. The satellite communications system as claimed in claim 1 in which any combination of said uplinks (35a), said downlinks (35b) and inter-satellite links (55) may be employed to accelerate delivery of said message throughout a particular orbital plane (14, 60, 63, 210).

7. A satellite communications system comprising:

a plurality of relay stations (34, 61,

     65);

a plurality of user terminals (212);

a plurality of satellites (12) operating in a plurality of Equatorial (14) and polar (60) or inclined (63,

     210) low Earth orbits;

each of said plurality of satellites (12) being capable of communicating with at least one of said plurality of relay stations and with one of said plurality of user terminals (212);

said plurality of user terminals (212) being randomly distributed, primarily in portions of the Earth (E) which are inhabited;

said plurality of relay stations (34) being distributed at locations on the Earth (E) which maximizes coverage for communicating and minimizes time to forward messages and data between any two of said plurality of user terminals (212);

at least one of said plurality of relay stations (34) being capable of functioning as a network operation and control center (NOCC); and

said relay stations (34) being capable of communicating with each other.

8. The satellite communications system as claimed in claim 7 in which said plurality of low Earth orbits (14, 60, 63, 210) includes four orbital planes (210), each of said orbital planes (210) being inclined at fifty degrees.

9. The satellite communications system as claimed in claim 8 in which said plurality of satellites (12) includes twenty-four satellites (12), six of said satellites (12) orbiting in each of said four orbital planes.

10. The satellite communications system as claimed in claim 7 in which said plurality of low Earth orbits (14, 60, 63, 210) includes five orbital planes, four of said orbital planes being inclined at fifty degrees and one of said orbital planes being inclined at zero degrees.

11. The satellite communications system as claimed in claim 10 in which said plurality of satellites includes thirty satellites, six satellites (12) orbiting in each of said five orbital planes.

12. The satellite communications system as claimed in claim 7 in which said plurality of low Earth orbits (14, 60, 63, 210) includes three orbital planes, two of said orbital planes being inclined at sixty degrees and one of said orbital planes being inclined at zero degrees.

13. The satellite communications system claimed in claim 7 in which said plurality of satellites (12), operating in said plurality of Equatorial (14) orbits, are capable of communicating over inter-satellite links (55).

14. The satellite communications system claimed in claim 13 in which said plurality of satellites (12), operating in said plurality of Equatorial orbits (14), are capable of using a combination of said ground relay stations (34) and said inter-satellite links (55) to relay data to a point of delivery.

15. The satellite communications system as claimed in claim 7 in which each one of said plurality of user terminals (212) includes a modem (300) capable of interconnecting a computer system RS232 port to a satellite (12).

16. The satellite communications system claimed in claim 15 in which said modem (300) is a module capable of interconnection, by itself or in combination, with an antenna (314), a personal computer (308), a parallel interface (304), an expanded memory (302), and a global positioning system (310).

17. The satellite communications system claimed in claim 15 in which said modem (300) includes an uplink transmitter (322) and a downlink receiver (320) capable of communicating with said plurality of satellites (12) a plurality of packets (225) of data and system overhead information.

18. The satellite communications system claimed in claim 15 in which

said modem (300) is capable of pre-compensating each of said plurality of user terminals (212) for Doppler shift of said downlink signal (216) from said plurality of satellites (12) minimizing frequency acquisition time by each of said plurality of satellites (12);

said modem (300) being capable of tracking a Doppler effect of said downlink signal (216) and scaling the measured value of said Doppler effect by a ratio of said uplink signal (214) frequency to said downlink signal (216) frequency, and adjusting the user terminal-satellite uplink signal (214) such that said uplink signal (214) is received at said satellite (12) corrected for said Doppler shift.

19. The satellite communications system as claimed in claim 7 in which said relay stations (34) are capable of communicating with each other using:

a very small aperture terminal (VSAT) link (222) through a geostationary satellite (218);

a public switched telephone network (PSTN) (220);

a link through a large, low Earth orbit communications satellite (12); and

a link through a network of relay stations (224) on the surface of the Earth (E) at the Equator (16).

20. The satellite communications system as claimed in claim 19 in which at least one of said plurality of user terminals (212) is adapted to tracking and reporting a moving object'"'"'s position and environment, said user terminal (212) including

a global positioning system (GPS) module (310);

environmental sensing instrumentation (356);

energy sensing instrumentation (354);

a modem (300);

an antenna (314);

said modem (330) coupled with said antenna (314); and

said GPS module (310) and said environmental sensing instrumentation (356) being coupled to said modem (300) and supplying geographical position information, environmental data and sensed energy data which is then transmitted as digital data to a receiving party through such combination of said terminal-satellite uplink (214), said relay station-satellite links (35a, 35b), said VSAT link (222) and said public switched telephone network (220) as minimizes time for transmission.

21. The satellite communications system as claimed in claim 20 in which said user terminal (212) adapted to tracking and reporting a moving object'"'"'s position and environment, is housed in a low cost buoy (352);

said low cost buoy (352) being deployed in a maritime environment.

22. The satellite communications system as claimed in claim 19 in which at least one of said plurality of user terminals (212) is adapted to monitoring data from systems, movable devices and devices with low data rate contained within a structure (392) which shields a user'"'"'s radio signal from a satellite (12), said user terminal (212) including:

a data input device (391) for supplying digital business, manufacturing and related information;

a personal communication service (PCS) system (394) located within said structure (392);

a coupling device (396);

an antenna (314);

a modem (300);

said modem coupled with said antenna (314);

said data input device (391) being coupled to an input of said PCS system (294) through said coupling device (296);

said PCS system (394) coupled at an output to said modem (300) of said user terminal (212); and

said business, manufacturing and related information being relayed from said input data device (391) through said PCS system to said modem (300) for transmission by said user terminal (212) to a receiving party through a combination of said terminal-satellite uplink (214), said relay station-satellite links (35a, 35b), said terminal-satellite downlink (216), said VSAT link (222) and said public switched telephone network (220) as minimizes said time to forward said digital data to said receiving party.

23. The satellite communications system as claimed in claim 19, in which a plurality of said user terminals (212) are adapted to an interactive television system (360) which uses direct television programming supplied by a broadcaster, each of said plurality of user terminals (212) including:

an integrated antenna system (365) including

a small television dish antenna (364) for receiving a television satellite signal (361) and an integrated whip antenna (362) for communication with said satellite communication system satellites (12);

a modem (300);

said integrated antenna system (365) coupled by coaxial cable (363) to said modem (300);

a television converter (366) integrated with said modem (300);

a television receiver (372) for displaying said television satellite signal (361) to a user;

said television receiver (372) coupled to said converter (366);

a data input device (368);

said user being capable of entering interactive responses to said television broadcaster by means of said data input device (368); and

said responses being transmitted by said user terminal (212) as digital data to one of said communication system satellites (12) for delivery to said broadcaster through such combination of said terminal-satellite uplink (214), said relay station-satellite links (35a, 35b), said terminal-satellite downlink (216), said VSAT link (222) and said public switched telephone network (220) as minimizes time to forward said digital data to said receiving party.

24. The satellite communications system claimed in claim 7 which further includes:

said plurality of satellites (12) having dynamic, adaptive channel assignment means for monitoring a pool of radio frequencies in a 148.0 to 149.9 MHz band and assigning channels to said plurality of user terminals (212) as available;

said dynamic, adaptive channel assignment means capable of scanning said pool of radio frequencies in a half-second interval for signals indicating channel usage, projecting channel usage for an ensuing half-second and thereafter instructing a calling user terminal (212) which channel to use.

25. The satellite communications system claimed in claim 24 in which said dynamic, adaptive channel assignment means includes a computer subsystem (324) having an algorithm for said projecting channel usage, said algorithm based on a sample history of scanning for said half-second intervals.

26. The satellite communications system as claimed in claim 7 in which:

said plurality of satellites (12), said plurality of user terminals (212) and said plurality of relay stations (34, 61,

     65) are capable of transmitting and receiving a plurality of packets (225) of data and system overhead information;

said plurality of satellites (12) are also capable of transmitting a downlink signal (35b,

     216) having a spectrum divided into four segments, each one of said segments being used in one of said four orbital planes;

said downlink signal (35b,

     216) includes a plurality of frames of 500 millisecond duration;

said downlink signal (35b,

     216) has a frequency shift keying (FSK) modulation and a quadraphase shift keying (QPSK) modulation of said packet transmissions in each of said plurality of frames in a time-shared manner;

said plurality of satellites (12) are also capable of receiving an uplink signal (35a,

     214) in which said quadraphase shift keying (QPSK) modulation is used for transmitting said plurality of packets (225);

said plurality of satellites (12) are also capable of receiving a user terminal-satellite uplink signal (214) and transmitting a user terminal-satellite downlink signal (216) having a variable data rate, said data rate variable from a low rate to provide for reduced burst power demand and reduced cost of equipment for said user terminals (212), to a high rate for rapid transmission of data;

said user terminal-satellite uplink signal (214) uses a combination of random access and frequency division multiplexing (FDM); and

said downlink signal (35b,

     216) and said relay station-satellite uplink signal (35a) uses a time division multiplexing;

said plurality of satellites (12) and said user terminals (212) are also capable of employing an auction protocol in a first burst of data in which said satellite (12) announces a level of message traffic being currently accepted for storage and forwarding, said level of message traffic being variable from a most expensive, fastest forwarding traffic to a least expense, slowest forwarding traffic.

27. The satellite communications system as claimed in claim 26 in which said variable data rate for a user terminal-satellite uplink signal (214) ranges from 9.6 kbps to 300 bps, and said variable data rate for a relay station-satellite downlink signal (35b) ranges from 24 kbps for QPSK modulation to 6 kbps for FSK modulation.

28. A method of satellite communications comprising the steps of:

providing a plurality of relay stations (34, 61,

     65);

distributing said plurality of relay stations (34) at locations on the Earth (E) which maximize coverage for communicating and minimize time to forward messages and data between any two user terminals (212);

providing a plurality of user terminals (212);

distributing said plurality of user terminals (212) randomly, primarily in portions of the Earth (E) which are inhabited;

operating a plurality of satellites (12) in a plurality of Equatorial (14), polar (60) and inclined (63,

     210) low Earth orbits;

communicating between each of said plurality of satellites (12) and at least one of said plurality of relay stations (34) and said plurality of user terminals (212); and

communicating, one with another, between said relay stations (34).

29. The method of satellite communications as claimed in claim 28 in which communicating between each of said plurality of satellites (12) and at least one of said plurality of relay stations (34, 61, 65) and said plurality of user terminals (212) further includes the steps of:

transmitting and receiving a plurality of packets (225) of data and system overhead information between said plurality of satellites (12), said plurality of user terminals (212) and between said plurality of satellites (12) and said plurality of relay stations (34, 61,

     65);

transmitting a relay station-satellite downlink signal (35b) and a user terminal-satellite downlink signal (216) from said plurality of satellites (12), each said downlink signal (35b,

     216) having a spectrum divided into four segments, each one of said segments being used in one of said four orbital planes;

said downlink signal (35b,

     216) including a plurality of frames of 500 millisecond duration;

modulating said downlink signal (35b,

     216) using a frequency shift keying (FSK) modulation and a quadraphase shift keying (QPSK) modulation of said packet transmissions in each of said plurality of frames in a time-shared manner;

receiving with said plurality of satellites (12) a relay station uplink signal (35a) in which said quadraphase shift keying (QPSK) modulation is used for transmitting said plurality of packets (225);

receiving a user terminal-satellite uplink signal (214) with said plurality of satellites (12) and transmitting a user terminal-satellite downlink signal (216) having a variable data rate, said data rate variable from a low rate to provide for reduced burst power demand and reduced cost of equipment for said user terminals (212), to a high rate for rapid transmission of data; and

multiplexing said user terminal-satellite uplink signal (214) using a combination of random access and frequency division (FDM) multiplexing;

multiplexing said downlink signal (35b,

     216) and said relay station-satellite uplink signal (35a) using a time division multiplexing (TDM); and

employing an auction protocol in a first burst of data in which said satellite (12) announces to said user terminals (212) a level of message traffic being currently accepted for storage and forwarding, said level of message traffic being variable from a most expensive, fastest forwarding traffic to a least expense, slowest forwarding traffic.

30. The method as claimed in claim 28, in which the step of providing a plurality of user terminals (212) and the step of providing a plurality of relay stations (34, 61, 65), includes the steps of:

deploying a low-cost buoy (352) in a maritime location;

said low-cost buoy (352) containing

environmental and weather instrumentation (356) for collecting environmental data;

an underwater listening device (354) for collecting vessel-tracking data;

a position-determining device (LORAN, GPS) (310) for collecting positioning data;

coupling said relay stations (34, 61,

     65) to a public switched telephone network (PSTN) (220); and

transmitting said environmental, tracking and positioning data from a user terminal (212) to a receiving party by communicating through at least one of said satellites (12), one of said relay stations (34, 61,

     65) and said PSTN (220).

31. The method as claimed in claim 28, in which the step of providing a plurality of user terminals (212) and the step of providing a plurality of relay stations (34, 61, 65), includes the steps of:

providing an integrated antenna system (356) at a site of a television viewer;

said integrated antenna system (356) having a first receiving antenna (364) for receiving broadcast television signals (361) provided by a broadcaster from a direct-broadcasting satellite (382), and having a second antenna 362 for communication with at least one of said plurality of satellites (12);

providing an integrated television converter/tuner (366) having a non-voice, non-geostationary satellite modem (300);

coupling said television converter/tuner (366) to said integrated antenna system (356);

coupling a data input device (368) and a television receiver (372) for displaying said television signals (361), to said integrated television converter/tuner (366);

coupling said relay stations (34, 61,

     65) to a public switched telephone network (PSTN) (220); and

said television viewer sending responses to said broadcast television signals (361) displayed on said television receiver (372) to said broadcaster by entering said responses on said data input device (368) and transmitting said responses through at least one of said satellites (12), one of said relay stations (34, 61,

     65) and said public switched telephone network (220) to said broadcaster.

32. The method as claimed in claim 28, in which the step of communicating between each of said plurality of satellites (12) and at least one of said plurality of relay stations (34) and said plurality of user terminals (212), includes the step of:

providing communications to one or more of said plurality of satellites (12) from movable devices (391) which are shielded from radio signals (216,

     214) transmitted and received by said satellites (12) by a man-made or natural structure (392), by relaying data from said movable devices (391) through a low-power, personal communication system (394) to a nearby, integrated user terminal (398) capable of communicating with at least one of said plurality of satellites (12).

33. The method as claimed in claim 28, in which the step of communicating between each of said plurality of satellites (12) and at least one of said plurality of relay stations (34) and said plurality of user terminals (212), includes the steps of:

obtaining said Universal Coordinated Time (UTC) signals provided by the National Bureau of Standards, through a communication link (35a,

     220);

broadcasting said Universal Coordinated Time (UTC) signals through said plurality of satellites (12);

receiving said Universal Coordinated Time (UTC) signals at one of said plurality of user terminals (212);

coupling one of said plurality of user terminals (212) to a clock in a local clock system;

said local clock system capable of responding to Universal Coordinated Time (UTC) signals;

passing said Universal Coordinated Time (UTC) signals to said local clock system; and

synchronizing said clock in said local clock system to said Universal Coordinated Time (UTC) signals.

34. The method as claimed in claim 28, in which the step of distributing said plurality of user terminals (212) randomly, primarily in portions of the Earth which are inhabited, and the step of providing a plurality of relay stations (34, 61, includes the steps of:

coupling a user terminal (212) to a monitoring device connected to a remotely installed system;

said monitoring device capable of delivering a signal indicating proper functioning of said remotely installed system to said user terminal (212);

monitoring proper functioning of said remotely installed system with said monitoring device and producing said signal;

coupling said relay stations (34, 61,

     65) to a public switched telephone network (PSTN) (220); and

transmitting said signal through at least one of said satellites (12), at least one of said relay stations (34, 61,

     65) and said public switched telephone network (220) to a receiving party.

35. The method as claimed in claim 28, in which the step of communicating between each of said plurality of satellites (12) and at least one of said plurality of relay stations (34) and said plurality of user terminals (212), includes the steps of:

obtaining commercial market information in real time through one or more communication links (35a, 35b,

     220);

broadcasting said commercial market information through said plurality of satellites (12); and

receiving said commercial market information at least one of said plurality of user terminals (212) for use in commercial transactions.

36. A method of satellite communications comprising the steps of:

providing a plurality of Equatorial, middle-latitude and polar relay stations (34,

     61);

said relay stations being located circumferentially along Earth'"'"'s Equator (16), in regions of Earth'"'"'s middle-latitudes and near Earth'"'"'s poles, respectively;

operating a first satellite (12) in an Equatorial, low Earth orbit (14);

operating a second satellite (12) in an inclined, low Earth orbit (60, 63,

     210);

communicating between said first satellite (12) and one of said plurality of Equatorial relay stations (34) over uplinks (35a) and downlinks (35b), and with one of said plurality of satellites in Equatorial orbit (14) over inter-satellite links (55);

communicating between said second satellite (12) and at least one of said plurality of Equatorial relay stations (34), middle-latitude relay stations (34) and polar relay stations (61);

storing a message from a first Equatorial relay station (34) in said first satellite (12) and forwarding said message to a second Equatorial relay station(34); and

receiving said message from said second Equatorial relay station (34) with said second satellite (12) and forwarding said message to at least one of said plurality of middle-latitude relay stations (34) and polar relay stations (61).

37. The method of satellite communications as claimed in claim 36 in which communicating between said first satellite (12) and one of said plurality of Equatorial relay stations (34) over uplinks (35a) and downlinks (35b), and with one of said plurality of satellites in Equatorial orbit (14) over inter-satellite links (55), further includes the step of employing any combination of said uplinks (35a), said downlinks (35b) and said inter-satellite links (55) to accelerate delivery of said message throughout a particular orbital plane (14, 60, 63, 210).