Abstract: The present invention provides a method for custom coding uplink signals and downlink beams in a satellite communications system. The method includes the step of applying, at a ground station (100), an outer code (102) to an uplink signal to produce an outer coded uplink signal. Next, the ground station (100) applies a selected reduced complexity inner code (104) to the outer coded uplink signal to produce a concatenated coded uplink signal. The ground station (100) transmits the concatenated coded uplink signal to a satellite (110). At the satellite (110), the inner code of the concatenated coded uplink signal is decoded (116) to produce an outer coded satellite data stream. Next, the satellite (110) applies a selected inner code (120) to a portion of the outer coded satellite data stream to produce a concatenated coded satellite data stream. The satellite (110) then transmits the concatenated coded satellite data stream in a downlink beam to a destination ground station (126).

Abstract: Systems and methods for protecting privacy in transmitting an analog information signal. The present invention combines the information signal with an analog random signal generated by a chaotic circuit and transmits the signal. The received signal is synchronized using a receiving chaotic circuit. The received signal is demodulated using a synchronized replica of the analog random signal. The information signal is recovered since the product of the random signals generated in the transmitter and in the receiver, is unity. Techniques used in the present invention for generating chaos, synchronization, and signal recovery are also disclosed.

Abstract: A method for maximizing satellite downlink information rate is disclosed. A ground transmitter (102) applies an outer block code to a data channel, modulates it, and transmits an uplink data stream (104) to a satellite (106) which demodulates the uplink data stream to produce a demodulated uplink data stream consisting of 1 to N user channels (230). The method uses a first multiplexer (232) to produce 1 to M multiplexed data signals (234) which are fed into quality encoders (236). The quality encoders (236) encode the multiplexed data signals (234) according to a selected quality level to produce custom-coded data signals (238). The level of coding applied to the custom-coded data signals (238) may be controlled by information received by a channel measurement element (250). Next, the method passes the custom-coded data signals (238) into a second multiplexer (240) which produces one multiplexed data stream (242).

Abstract: The present invention provides a method for custom coding uplink signals and downlink beams in a satellite communications system. The method includes the step of applying, at a ground station (100), an outer code (102) to an uplink signal to produce an outer coded uplink signal. Next, the ground station (100) applies a selected reduced complexity inner code (104) to the outer coded uplink signal to produce a concatenated coded uplink signal. The ground station (100) transmits the concatenated coded uplink signal to a satellite (110). At the satellite (110), the inner code of the concatenated coded uplink signal is decoded (116) to produce an outer coded satellite data stream. Next, the satellite (110) applies a selected inner code (120) to a portion of the outer coded satellite data stream to produce a concatenated coded satellite data stream. The satellite (110) then transmits the concatenated coded satellite data stream in a downlink beam to a destination ground station (126).

Abstract: A method for enhancing the performance of a communications system is disclosed. The system generally includes an originating ground station (300) which produces error-control coded uplink signals and transmits the coded uplink signals to a satellite (310). The system also includes a destination ground station (326) which receives a downlink beam from the satellite (310). The method includes the steps of receiving uplink signals transmitted by an originating ground station (300) at a destination ground station (326) and determining a downlink channel signal quality indication (504) at the destination ground station (326). The method also includes the steps of measuring an error rate associated with at least a portion of a downlink beam at said destination ground station (326) and determining an operating point (506) relative to a desired performance curve (502) based on the signal quality indication (504) and the error rate.