Abstract: Satellite-based communication systems and methods that substantially collocate multibeam satellites and allow for incremental addition of network capacity by launching additional substantially collocated satellites. Exemplary systems and methods comprise a plurality of substantially collocated multi-beam satellites that are launched and that are configured to provide beam coverage using substantially the same multibeam pattern of beams so that the beam coverage of both satellites is available for simultaneous use. A processor onboard each of the satellites configures the multibeam pattern of beams. The processor assigns a frequency and polarization to each beam based upon frequency re-use, system performance and capacity requirements, assigns overlapping bandwidth allocations within a beam, assigns bandwidth and power per bandwidth, and selectively adjusts beam capacity and power based on network traffic requirements.

Abstract: Communications apparatus, such as a multibeam satellite communications system on-board a satellite, or terrestrial communications system, and methods that use a data routing technique that is based on the assignment of one or more codes corresponding to a destination beam. In particular, data routing is performed based on a CDMA code. The communications apparatus and methods allow simplified processing of the data address and routing of the data.

Abstract: Communications apparatus, such as a multibeam satellite communications system on-board a satellite, or terrestrial communications system, and methods that use a data routing technique that is based on the assignment of one or more codes corresponding to a destination beam. In particular, data routing is performed based on a CDMA code. The communications apparatus and methods allow simplified processing of the data address and routing of the data.

Abstract: A flexible bandwidth satellite communications system, having two communications quartets with at least one controller spot beam per quartet. Each quartet comprises four transponders having multiple type bandwidth filters with controllable pass-bands controlled by a gateway located in an opposite quartet.

Abstract: A Multi-Band Concentric Helical Antenna (20) operating in a novel conical mode, useful for general and satellite communications is disclosed. A higher frequency helix (24) is placed concentrically inside a lower frequency one (22). In one embodiment, each helix has four helical elements (22a-d, 24a-d). The outer helix is fed at a first frequency (f.sub.1) and the inner helix (24) is fed at a second frequency (f.sub.2). The second frequency (f.sub.2) may be greater than twice the first frequency (f.sub.1). Both helices (22, 24) have the same polarization. The pitch (P.sub.1, P.sub.2), diameter (D.sub.1, D.sub.2), and length (AL.sub.1, AL.sub.2) of the helices are chosen so that said antenna (20) radiates with approximately equal flux at all points in a far-field plane. Alternatively, two inner helices (24, 25) are placed concentrically within an outer helix (22).

Abstract: Methods and apparatus are disclosed which allow many satellites (A1-M, B1-N) in a plurality of Systems (A, B) to use the same radio frequencies (f1-n) so long as there is no interference between radio signals. The methods compute times (t) when satellite radio signals (32, 36) have overlapping reception areas or "footprints" (30, 35) on the Earth's surface (E) whereby a user's reception or transmission of a message would be interfered unless different frequencies (f1-n) are used for the "competing" signals. The methods use a timing algorithm that does not allow two satellites (Ai, Bi) which are "visible" at the same point on the Earth (E) to transmit on the same frequency (fi). In one preferred embodiment, a timing algorithm (48) produces a radio frequency use schedule (49) computed on the Earth from orbital data maintained in an ephemeris (46) of satellite communications systems (A, B) which communicate on frequencies (f1-n) giving rise to interfering radio signals.

Abstract: A demodulator unit is disclosed for spread spectrum apparatus utilized in a cellular mobile communication system. The cellular mobile communication system includes a plurality of fixed base stations connected with a central processor so that calls originating in any cell can terminate in any other cell. Each mobile unit has a unique set of time-frequency coded waveforms that are used for both transmission and reception. Message modulation is accomplished by digitizing the speech and encoding the resulting binary sequences into the set of waveforms available to the user, while detection is accomplished by the demodulator unit in which the phases of each received waveform are compared with those of the preceding waveform. The demodulator unit includes a tapped delay line which can have mixers before and after the delay line and can be a narrowband unit with delays and mixers.