US 5,392,450 AGranted

Satellite communications system

AssigneeGeneral Electric Company

InventorEdward J. Nossen

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Abstract

A multiple channel demand assignment multiple access (DAMA) system is configured as a spoke-and-hub star network in which a satellite relays information between each of many small-aperture terminals (SATs), which may be portable terminals (PTs), and a hub network control terminal (NCT) which receives requests from the PTs, allocates channel resources, and broadcasts housekeeping messages. The system has a reservation protocol using at least three separate data channels to take advantage of the inherent lack of adequate radiated power at the PTs: a NCT outbound channel is tightly packed with data, without guard spaces, and it uses typically 98% of the allocated power; separate return channels for data and reservations use little satellite power, with no need for extremely tight data packing. Guard spaces are included in the reservation channel to overcome the total range of propagation delay uncertainty without requiring knowledge of the location of a particular PT.

Claims20

Dependent claims

A satellite communications system, comprising:

a communications satellite having at least one translator;
at least one small-aperture terminal (SAT) capable of sending data transmissions to and receiving data transmissions from said communications satellite;
and
a hub network control terminal (NCT) capable of sending data transmissions to and receiving data transmissions from said communications satellite, and adapted to configure transmissions to and from the satellite into at least three data channels, with each of the three data channels being in a separate frequency band from a frequency band occupied by either other channel and with substantially all of the satellite transmission power allocated to the at least one small aperture terminal, and said three data channels comprising a first channel being used by the hub network control terminal to provide for initial contact to any of the at least one small aperture terminals desiring to communicate, a second channel being used by one desirous small aperture terminal to gain the attention of the hub network control terminal, and a third channel being used by the desirous small aperture terminal gaining the attention of the hub network control terminal to thereafter transmit information via the hub network control terminal.

1 more element

A satellite communications system, comprising:

a communications satellite having at least one translator;
at least one small-aperture terminal (SAT) capable of sending data transmissions to and receiving data transmissions from said communications satellite;
and
a hub network control terminal (NCT) capable of sending data transmissions to and receiving data transmissions from said communications satellite, and adapted to configure transmissions to and from the satellite into at least three data channels, with each of the three data channels arranged in a separate frequency band from a frequency band occupied by either other channel with a first channel being used by the NCT to provide for initial contact to any of the at least one small aperture terminals desiring to communicate, a second channel being used by one desirous small aperture terminal to gain the attention of the hub network control terminal, and a third channel being used by the desirous small aperture terminal gaining the attention of the hub network control terminal to thereafter transmit information via the hub network control terminal, with the three data channels allowing a plurality of small aperture terminals to communicate in time-sequential manner through the satellite and the hub network control terminal, with the hub network control terminal both causing each of the three data channels to be substantially continuously present at the satellite and implementing a demand-assignment-multiple-access (DAMA) protocol for facilitating said plurality of the small aperture terminals to communicate during each of a multiplicity of sequential time frames.

1 more element

A satellite communications system, comprising:

a communications satellite having at least one translator;
at least one small-aperture terminal (SAT) capable of sending data transmissions to and receiving data transmissions from said communications satellite;
and
a hub network control terminal (NCT) capable of sending data transmissions to and receiving data transmissions from said communications satellite, and adapted to configure transmissions to and from the satellite into at least three data channels, said three data channels comprising a first channel being used by the hub network control terminal to provide for initial contact to any of the at least one small aperture terminals desiring to communicate, a second channel being used by one desirous small aperture terminal to gain the attention of the hub network control terminal, and a third channel being used by the desirous small aperture terminal gaining the attention of the hub network control terminal to thereafter transmit information via the hub network control terminal;
and
means for providing at least one voice channel, with a control data message being insertable in a non-interfering manner within a stream of data on each voice channel, with the control data message provided in at least one associated data slot, and with the voice data in adjacent slots transmitted at a commensurate higher rate.

3 more elements

Dependencies are inferred from the claim text.