A GPS receiver in one embodiment includes an antenna which receives GPS signals at an RF frequency from in view satellites; a downconverter coupled to the antenna for reducing the RF frequency of the received GPS signals to an intermediate frequency (IF); a digitizer coupled to the downconverter and sampling the IF GPS signals at a predetermined rate to produce sampled IF GPS signals; a memory coupled to the digitizer storing the sampled IF GPS signals (a snapshot of GPS signals); and a digital signal processor (DSP) coupled to the memory and operating under stored instructions thereby performing Fast Fourier Transform (FFT) operations on the sampled IF GPS signals to provide pseudorange information. These operations typically also include preprocessing and post processing of the GPS signals. After a snapshot of data is taken, the receiver front end is powered down. The GPS receiver in one embodiment also includes other power management features and includes, in another embodiment the capability to correct for errors in its local oscillator which is used to sample the GPS signals. The calculation speed of pseudoranges, and sensitivity of operation, is enhanced by the transmission of the Doppler frequency shifts of in view satellites to the receiver from an external source, such as a basestation in one embodiment of the invention.

GPS receiver and method for processing GPS signals

A precision carrier frequency signal for calibrating a local oscillator of a GPS receiver which is used to acquire GPS signals. The precision carrier frequency signal is used to calibrate the local oscillator such that the output of the local oscillator, which is used to acquire GPS signals, is modified by a reference signal generated from the precision carrier frequency signal. The GPS receiver locks to this precision carrier frequency signal and generates the reference signal. In another aspect of the invention, satellite almanac data is transmitted to a remote GPS receiver unit from a basestation via a communication link. The remote GPS receiver unit uses this satellite almanac data to determine approximate Doppler data for satellites in view of the remote GPS receiver unit.

GPS receiver utilizing a communication link

Methods and apparatuses for distributing location-based information (i.e., information specific to a client's location or a location of interest to the client) to a client, which may be a mobile SPS receiver, via the Internet and in particular, the World-Wide Web. The client provides information about its location and/or a location of interest to a Web server. The Web server, based on the information, provides via the Internet information relating to the client's location or location of interest to the client.

Method and apparatus for providing location-based information via a computer network

A user accesses a server using a client. The client provides an identification code which serves to uniquely identify a remote sensor. The remote sensor is capable of providing information related to its position. The server interrogates the remote sensor and, in response, the remote sensor transmits positioning data to the server where it is analyzed to derive the location of the remote sensor. The location so determined is transmitted from the server to the client and is displayed at the client so that the user can identify the location of the remote sensor. The client and the server may be connected to a computer network and the client may use a web browser to interrogate the server. The remote sensor may be a SNAPSHOT GPS receiver or other GPS receiver or positioning device. The user display may be a simple position report, e.g., latitude and longitude, or a graphical report which provides an indication of the remote sensor's location superimposed on a map or other reference.

Client-server-based remote locator device

A repeater and associated method of use includes at least one antenna element for communicating in one direction and at least one antenna element for communicating in another direction. A radio frequency uplink path and a radio frequency downlink path are coupled between the antennas. At least one of the radio frequency uplink path or the radio frequency downlink path includes an adaptive cancellation circuit. The adaptive cancellation circuit is configured to generate a cancellation signal without requiring an injected signal. The cancellation signal, when added to a radio frequency signal in the respective uplink and downlink paths, substantially reduces feedback signals present in the radio frequency signal.

Repeaters for wireless communication systems

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

An intelligent digital beam former (10) in conjunction with a satellite based array antenna (20) provides a plurality of dynamically controllable antenna beams (52) for communication with subscriber units on earth's surface. The location of a subscriber unit (90) requesting communication services is determined and an individual antenna beams is formed and assigned to the subscriber unit. The antenna beam tracks the subscriber units as the satellite and/or the subscriber unit moves. The digital beam forming coefficients are dynamically adjusted and controlled to help maximize the signal quality of communications with the subscriber units.

Method and intelligent digital beam forming system with improved signal quality communications

An intelligent digital beam former (10) in conjunction with a satellite based array antenna (20) provides a plurality of dynamically controllable antenna beams (52) for communication with subscriber units (90) in response to demand for communication services. Geographic portions within the satellite's footprint that have a higher-demand for communication services are dynamically provided additional antenna beams while geographic portions having a lower demand for communication services are provided less antenna beams. When used on a non-geostationary satellite, the digital beam forming coefficients are dynamically adjusted to steer the antenna beams to maintain their ground location. The antenna beams are also shaped to help optimized geographic coverage.

Method and intelligent digital beam forming system responsive to traffic demand

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 constellations

An enhanced digital beamformer (EDBF) (210, FIG. 2) is provided for use in a transceiver subsystem (200, FIG. 2) for mitigating interference and increasing the frequency reuse factor in communication systems. The EDBF is used to produce wide nulls (520, FIG. 5) in at least one steerable antenna beam pattern. By directing wide nulls at undesired signals, the EDBF provides a more efficient processing of antenna beam patterns in communication systems. The EDBF is used in geostationary satellites, non-geostationary satellites, and terrestrial communication devices. The EDBF combines a unique algorithm, a special processor, and an array antenna to significantly improve the capacity of current and future communication systems, while remaining compatible with existing modulation techniques.

Stephen Chih-Hung Ma

Papers

CPS transform correlation receiver and method

Method and intelligent digital beam forming system with improved signal quality communications

Method and intelligent digital beam forming system responsive to traffic demand

Position locating and communication system using multiple satellite constellations

Method and apparatus for producing wide null antenna patterns