Abstract: A receiver despreads a spread spectrum sequence by partially despreading the spread spectrum sequence using an outer spreading code, and then despreading the partially despread sequence using an inner spreading code. This can advantageously save processing power. In one embodiment, the outer spreading code is despread with an analog circuit, and an inner spreading code is despread with a digital circuit. A modulator for a transmitter can generate a spread spectrum sequence by direct-sequence spreading data to generate a partially spread sequence and then spreading the partially spread sequence to generate the spread spectrum sequence.

Abstract: An apparatus and methods for communicating between or among global positioning system (GPS) receivers enhanced with wideband transmitters, which can include ultra wideband (UWB) transmitters. In one embodiment, WB pulses are precorrected by a transmitter to align with a clock common to both enhanced GPS receivers for autocorrelation, thereby simplifying WB or UWB receiver circuitry. One embodiment includes a circuit and method for adjusting the timing of a pulse by phase shifting the pulse by adjusting amplitude. The wideband pulses are used to communicate data between enhanced GPS receivers. A relatively long code can also be communicated between enhanced GPS receivers, thereby permitting the same WB signal to be used to determine range between the enhanced GPS receivers. The communicated data can include the absolute position of the enhanced GPS receiver, which when combined relative positioning from ranging data, can advantageously permit cooperatively positioning and/or navigation.

Abstract: A wireless network of multiple base stations, each communicating with multiple remote terminals, exhibiting simpler design and enhanced inter-user and inter-base interference rejection. The downlink from a base to the multiple remote terminals employs a combination of time division multiplexing (TDM) and time division multiple access (TDMA) to multiplex signals carrying data to the remote terminals, and spreads the multiplexed signal with a pseudo-random noise (PN) sequence. The uplink from each remote terminal to the respective base uses orthogonal code division multiple access (O-CDMA) coding to multiplex a variable number of channels for each remote terminal. Short O-code sequences are derived based on pseudo-random maximal length sequences and quadratic residue sequences to introduce sufficient randomness into the multiple access coding to reject inter-base interference without the use of PN signal spectrum spreading.

Abstract: An integrated satellite/cell system and equipment that provides low-cost telephony services to remote/rural and other previously non-served areas. Local communications is through wireless cell technology with inter cell communication between cells and between cells and the public switched telephone network supported through existing, non-processing satellites by means of satellite earth terminal stations at the remote sites. A demand assigned multiple access satellite network controlled through a open channel signaling and data provides single-hop, full mesh connectivity. The cell can be any cellular or cordless phone technology.

Abstract: A satellite communication system comprising of a central hub/gateway station and remote very small aperture terminal (VSAT) stations. VSAT inbound transmissions are spread in bandwidth using an assigned PN code sequence. This sequence is derived as a cyclic function of a base sequence for use by the group of VSATs. The gateway transmits a continuous outbound signal that functions as the network frequency and timing reference. In addition, the gateway periodically forms timing and frequency error estimates on each VSAT transmission and broadcasts these results over the outbound channel to the VSATs. Use of the outbound reference coupled with these time and frequency measurements enable all VSAT inbound transmissions within a group to be bit synchronized. Bit level synchronization enable the system to gain the full advantage of the correlation properties of the cyclic codes to improve multiple access performance as compared to asynchronous or chip synchronous code division multiple access (CDMA) techniques.

Abstract: A data receiver apparatus for recovering digital data signals from an M-ARY FSK modulated signal incorporates a dedicated linear discriminator, downstream of the data recovery process, in the carrier tracking loop. Because the signal modulation components are removed prior to tracking, only frequency error remains, which is employed by the linear discriminator for steering a VCO in the frequency tracking loop. This results in a closed loop step response that rapidly converges to a stable level, and a linear frequency estimation characteristic.