Motorola Corporation

Isaac N Durboraw, Iii

Stephen Chih-Hung Ma

Robert Henry Bickley

Raymond Joseph Leopold

David Moon Yee

Philip John Zucarelli

George William Muncaster

Philip R Horkin

A method and apparatus for detecting and tracking spread spectrum signals, such as Global Positioning System (GPS) signals, first obtain precision timing and frequency reference information from a relatively high-power, secondary signal, such as that emanating from a satellite of a low-earth orbit (LEO) satellite communications system, and then use such reference information to perform narrow-band detection of the GPS spread spectrum signal. Accordingly, spread spectrum signals are more efficiently detected and tracked, particularly in environments where they are attenuated by obstacles such as buildings or environmental barriers.

Method and apparatus for detecting spread spectrum signals using a signal from a secondary source

In a GPS receiver, power is conserved by powering down P-code circuitry during and utilizing C/A code circuits during times when interfering signals, such as spoofing signals, are not detected. When spoofing is detected, the P-code circuitry is powered up so that the GPS receiver can continue to operate in the presence of spoofing.

Spoofer detection power management for GPS receivers

In a Global Positioning System (GPS) receiver, a significant improvement in the detection of GPS data in the presence of high interference levels is provided. In the receiver, data from multiple frames of GPS data are stacked in a memory. The stacked data is then utilized to determine the GPS data.

GPS data collection in high noise-to-signal ratio environments

A communication and position locating system (2) suitable for air traffic control is described. Multiple satellites (40) are provided in two geosynchronous constellations. One constellation (e.g., 4 satellites) has a first closed ground track (14). The other (e.g., 2 satellites (161, 182)) has a different ground track (18) or is geostationary, located outside of the first ground track (14). Geolocation information is transmitted by the satellites (40) to aircraft (28) and ground stations (26) so that aircraft (28) can determine their current position. A pseudo range correction map is provided to the aircraft (28) by the base stations (26) to permit differential geolocation measurements. The satellites (40) include communication transceivers (80) so that aircraft (28) can communicate voice and data to other aircraft (28) and to the ground stations (26, 30, 32) and automatically report their position to air traffic control centers (30), e.g., via the satellites (40). High positional accuracy over large geographic areas is obtained.

Position locating and communication system using multiple satellite

A GPS receiver (10) with processor (14, 16), memory (18), input (20) and indicator (22), uses conventional code pseudorange and carrier phase to provide a compass function. The receiver antenna (12) is desirably held stationary while the directional vectors toward the satellites and for the desired heading (21) are computed, the rate of change of carrier phase determined and future carrier phase predicted. The antenna (12) is then moved in a closed path (11) while the differences between predicted and actual carrier phase are measured and converted to positional perturbations which are resolved along the desired heading (21) and normal thereto. As the antenna (12) moves around the closed path (11), the resolved perturbations have maxima, minima or change sign and the processor (14, 16) uses this to trigger the indicator (22, 222) so that the desired heading is apparent to the user.

Direction indicating apparatus and method

A subscriber unit for communicating with a satellite communication system. This subscriber unit receives and transmits digital data from satellites of a satellite communication system. In addition, the subscriber unit self-determines its own position and transmits this position to the satellites of the satellite communication system. In this way, the satellite communication sytem knows the position of each subscriber unit so that communications may be established more efficiently. In addition, the position of the subscriber unit is automatically determined from the received GPS signals and reported to the satellite communication system for other uses such as asset management and search and rescue operations.

Position aided subscriber unit for a satellite cellular system

A method for rapid acquisition of multiple GPS signals builds upon fast Fourier transformation of input GPS signals to simultaneously track multiple satellites and derive psuedorange measurements that are suitable for navigation solution. The method utilizes 2M samples of the reference signal with N samples of the signal set from the satellites (one millisecond of actual data) to directly compute the fractional psuedorange values for four (4) or more satellites. The FFT process is incorporated with a process to determine an integer psuedorange. The integer psuedorange is then combined with a fractional psuedorange to define the GPS navigation solution.

CPS transform correlation receiver and method

A communications system including main and auxiliary antennas for reducing sidelobe interference with circuitry included in the feedback loop for estimating clutter by determining the difference between repetitious signals and subtracting a portion of the difference in the proper time sequence, relatively rapid changes between repetitous signals being composed generally of clutter.

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Scottsdale, AZ, United States of America

Isaac N Durboraw, Iii