Abstract: A power gated variable hop cycle beam laydown (700) manifests itself as first cells (C, D) supported by a first hop cycle, second cells (G, H) supported by a second hop cycle, and transition cells (E, F) supported by a transition hop cycle. The transition hop cycle uses power gating to transition the laydown (700) from cells (C, D) operating at the first hop cycle to cells (G, H) operating at the second hop cycle. To this end, the transition hop cycle power gates its downlink beam for a portion of time needed to reduce interference between nearby (e.g., adjacent) cells.

Abstract: A downlink beam frame signal processing system (100) for a communication satellite includes a packet switch (608) that routes self addressed uplink data to a memory (804). The memory (804) stores queues for at least a first and a second downlink beam hop locations (302, 304). The processing system (100) also includes a power amplifier (108) that amplifies a waveform formed using the uplink data. A power gating circuit (1200) coupled to the power amplifier (108) includes a power gate input (1216) responsive to a power gating signal to remove RF power from at least a portion of the waveform before transmission.

Abstract: A frame signal (100) for communicating payloads (104, 110) of data includes a first payload field (104) and a first header field (102) with a first frame type indicator (120). The frame signal (100) also includes a second payload field (110) and a second header field (108) smaller than the first header field (102) that includes a second frame type indicator (128). The first payload field (104), first header field (102), second payload field (110), and the second header field (108) are encapsulated in a single frame (100) to provide multiple payload delivery with reduced overhead compared to individually transmitted single payload frames.

Abstract: A downlink frame processing system (200) includes a packet switch (608) routing self addressed uplink data (706) from an input port to an output port, a memory (804) coupled to the output port, and a downlink scheduler (802) coupled to the memory (804). The memory (804) includes storage for at least two downlink beam hop locations (302, 304). The downlink scheduler (802) processes from one of a plurality of segments at least one scheduling entry (1312) that includes, for example, a header field (1316) defining at least one of a payload and frame type (1404) for at least one of a payload and frame (1200) to be transmitted, and payload data pointers (1502, 1504, 1506) into the memory (804).

Abstract: The present invention provides a highly accurate synchronization method for a satellite communication system (100). The system maintains a downlink symbol counter at an earth terminal and determines a downlink symbol count representative of the time of arrival of a burst transmitted from the earth terminal to a satellite (106, 206). The earth terminal adjusts the downlink symbol counter to correspond to the downlink symbol count (136, 220) upon arrival of a predetermined reference point in a downlink frame. A timing error may initially be determined by launching an entry order wire from the earth terminal to the satellite (116). The timing error may be transmitted to the earth terminal using a correction code which indicates the transmission is early, late, absent, or no change is required (134, 218). The terminal may make additional periodic timing adjustments based on the length of the propagation path between the earth terminal and the satellite (108, 208).

Abstract: A method and apparatus for closed-loop power threshold leveling for a satellite communication system. An aspect of the present invention includes a plurality of user earth terminals (UET), a satellite and a network control center (NCC). The NCC polls the UETs to obtain power profile information. When polled, the UELTs form power profile responses and send the responses back to the NCC. The NCC forms a power profile database and statistically analyzes the power profile information to determine an uplink power threshold adjustment. The NCC transmits the uplink power threshold adjustment to the satellite, which adjusts an on-board uplink power level threshold in response to the uplink power threshold adjustment. In systems using mutltiple coding levels, the NCC determines uplink power offset values corresponding to the individual coding levels. The NCC delivers the uplink power offset values to the UETs which update their local power offset values.

Abstract: The present invention provides a method and apparatus for arbitration among the inputs of a crossbar cell switch. The input cells of the crossbar cell switch are stored at their respective input ports in input queues prior to switching. The first cell of each input queue is known as the Head of Line (HoL) cell. For each set of HoL cells that may be directed to a specific output port, the HoL cell with the largest input port queue size is assigned to be switched during the current switching epoch. The method and apparatus for arbitration allows the crossbar cell switch to operate with smaller input queues, increasing the throughput of the switch and minimizing both the transit delay for the data cells through the switch and the buffer size needed to accommodate input queues.

Abstract: An initial entry processor (40) for use in a processing satellite (12) in a satellite based communications system (10) is provided having a buffer (62), a detection and timing circuit (64) and an identity circuit (66). The buffer (62) stores an initial entry burst (54) transmitted from at least one terrestrial terminal (14) to the processing satellite (12). The detection and timing circuit (64) detects the initial entry burst (54) and determines a time of arrival of the initial entry burst (54) relative to an initial entry burst slot (52). The identity circuit (66) determines an identity of the terrestrial terminal (14) that transmitted the initial entry burst (54) such that the time of arrival is used by the identified terrestrial terminal (14) during subsequent communications with the processing satellite (12).

Abstract: A ground terminal renders feasible a communications system that locates two satellites at the same node along the geostationary arc. Each satellite is capable of receiving RF signals through an uplink channel and transmitting RF signals through a downlink channel distinct from the uplink channels. The ground terminal is able to transmit RF signals to only one of the satellites, but can receive RF signals from both of the satellites. The ground terminal includes an antenna, an RF signal processor that includes two demodulators for processing signals from the two downlink channels, and a data processor.

Abstract: A communications system includes two satellites located at the same node along the geostationary arc each capable of receiving RF signals through an uplink channel and transmitting RF signals through a downlink channel distinct from the uplink channels. At least two user terminals are in the system, with each user terminal able to transmit RF signals to only one of the satellites, but at least one of the user terminals is able to receive RF signals from both of the satellites.

Abstract: The present invention is a demodulator and a method of demodulating burst communications. A demodulator (100, 200) includes a phase angle source (18), coupled to a current received burst communication, which provides a phase angle of the current received burst communication; a comparator (20), coupled to the phase angle source and a source of an estimated phase angle, which provides an output signal representing an angular difference between a phase of the current received burst communication and the estimated phase angle; and a phase lock loop (20), coupled to the output signal, which provides the estimated phase angle. The phase lock loop includes a Doppler accumulator (102) which provides a Doppler output which provides compensation in the estimated phase angle for the Doppler effect produced by relative motion between the demodulator and a source of the burst communications.

Abstract: The present invention is a demodulator and a method of demodulating burst communications. A demodulator (100, 200) includes a phase angle source (18), coupled to a current received burst communication, which provides a phase angle of the current received burst communication; a comparator (20), coupled to the phase angle source and a source of an estimated phase angle, which provides an output signal representing an angular difference between a phase of the current received burst communication and the estimated phase angle; and a phase lock loop (20), coupled to the output signal, which provides the estimated phase angle. The phase lock loop includes a Doppler accumulator (102) which provides a Doppler output which provides compensation in the estimated phase angle for the Doppler effect produced by relative motion between the demodulator and a source of the burst communications.

Abstract: Coordination of processing satellite uplink transmission and downlink transmission is achieved by an uplink encoder (418) and uplink modulator (420) which incorporate an adjustable IF amplifier (417) at a ground terminal (400). Information about data traffic transmission errors detected in a satellite (100) is formed into ATM traffic report cells by a cell former (157). The traffic report cells are sent on the downlink to the ground terminal. The traffic report cells are used to adjust the power level of the IF amplifier for the particular channel and slot for which errors were detected.