Abstract: A method and apparatus for measuring time related to satellite data messages which are used with satellite positioning systems (SPS). In one method, a first record of at least a portion of a satellite data message is received at an entity, which is typically a basestation. The first record is compared with a second record of the satellite data message, where the first record and the second record overlap at least partially in time. Then a time is determined from this comparison, and this time indicates when the first record (or the source from which the first record was obtained) was received at a remote entity which is typically a mobile SPS receiver. Various other methods of the invention are described and various apparatuses of the invention are also described. The methods and apparatuses measure time of day using SPS signals without reading the satellite data messages which are transmitted as data within these signals.

Abstract: A method and apparatus is disclosed for reducing cross-interference between received satellite signals in a satellite positioning system receiver. A satellite positioning receiver receives satellite signals from a plurality of satellites. Spurious signals when processing a weak received satellite signal due to interference by a stronger received signal are reduced by estimating certain characteristics of the stronger signal, creating an interference waveform based on these estimated characteristics, and subtracting this interference waveform from a set of correlation outputs for the weaker signal to remove the interference effects of the stronger signal. Alternatively, a subset of these correlation outputs are ignored where the interference waveform produces strong spurious signals.

Abstract: A method and apparatus for determining a reference time associated with a satellite positioning system. In turn, the reference time, in one embodiment, may be used to determine other navigational information. Such navigational information may include, for example, the location/position of a satellite positioning system (SPS) receiver. In one embodiment, a relative velocity between an SPS receiver and a set of one or more satellites is used to determine an offset between time as indicated by the SPS receiver and the reference time. According to another embodiment of the invention, an error statistic is used to determine the reference time. According to yet another embodiment of the invention, two records, each representing at least a portion of a satellite message, are compared to determine time. In one implementation, the SPS receiver is mobile and operates in conjunction with a basestation to determine time and/or other navigational information according to one or a combination of the methods described.

Abstract: Methods and apparatuses which use satellite position system (SPS) reference receivers. In one example of the invention, a plurality of SPS reference receivers, such as Global Positioning System (GPS) reference receivers, each having a known position, are dispersed over a geographical region. Each of the SPS reference receivers transmits into a communication network, a representation of at least a portion of a satellite navigation message, such as satellite ephemeris data, received from SPS satellites in view of the particular SPS reference receiver. A plurality of digital processing systems, such as a first and a second digital processing systems, are coupled to the communication network to receive the satellite ephemeris data which is transmitted through the communication network.

Abstract: A method and apparatus of acquiring and tracking satellite positioning system signals in a highly parallel correlator disclosed. A pseudo-random noise correlation operation is performed on an input satellite positioning system signal to provide a correlated output. The input satellite positioning system signal is input in parallel to a number of parallel correlators. Each parallel correlator contains a multi-correlator unit which processes and stores multiple phases of a correlated pseudo-random noise signal using common adder and multiplier circuitry.

Abstract: Methods and apparatuses for deriving an approximate Doppler for a satellite positioning system (SPS) receiver from an approximate location which is obtained from a cellular communication system information source. In one embodiment, an approximate location of the SPS receiver is derived from the information source and this approximation location is used to determine approximate Dopplers to a plurality of SPS satellites at a given time. The approximate Dopplers are then used to reduce processing time in either determining pseudoranges to the SPS satellites or acquiring signals from the SPS satellites. In another aspect of the invention, a reference signal is used to provide a local oscillator signal which is used to acquire SPS signals in an SPS receiver. This reference signal is extracted from a data signal modulated on a carrier frequency.

Abstract: A system and method for processing in a distributed manner satellite position system (SPS) information. In one example of the invention, a first mobile SPS receiver receives SPS signals from a plurality of SPS satellites and transmits a position information to a wireless cell based station which is coupled to a first communication network. The wireless cell based station is coupled to a first digital processing system which receives the position information from the wireless cell based station and calculates a location of the first mobile SPS receiver based upon the position information. The first digital processing transmits this location, usually without any presentation of this location on the first digital processing system, to a remotely located application digital processing system which presents the location to a user of the application digital processing system.

Abstract: A method and apparatus of determining the time for a global positioning system receiver is disclosed. Timing signals derived from a communication system, such as cellular phone transmission signals, are received by a GPS receiver and decoded to provide accurate time information. The timing signals may be in the form of synchronized events marked by timing indicators, or as system time information. The timing signals in combination with satellite position signals received by the GPS receiver are used to determine the position, of the GPS receiver.

Abstract: A method and an apparatus which acquire satellite positioning system (SPS) signals in an SPS receiver. Information on time of day, approximate receiver location, and satellite positions are used to reduce the time to search and acquire signals from one or more SPS satellites. In an example of a method of the invention, a first pseudorange to a first SPS satellite is determined, and an approximate location of the SPS receiver is determined. An estimated pseudorange for a second pseudorange to a second SPS satellite is determined from the approximate location and a satellite position of the second SPS satellite. The SPS receiver then searches for SPS signals from the second SPS satellite in a range determined by the estimated pseudorange. Typically, this method reduces the search time to initially acquire SPS signals from the second SPS satellite, and the estimated pseudorange is not based on a previously determined pseudorange for said second SPS satellite.

Abstract: A GPS receiver having a low power mode of operation 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; and a digital signal processor (DSP) coupled to the memory and operating under stored instructions thereby performing operations on the sampled IF GPS signals to provide pseudorange information. In one example, after the sampled IF GPS signals have been stored in the memory, the GPS receiver front end is powered down and the DSP is powered up. The GPS receiver in one embodiment also includes other power management features.

Abstract: A method and apparatus is disclosed for adaptively processing Global Positioning System (GPS) signals in a GPS receiver. An adaptive method of processing GPS signals optimizes the initial acquisition of GPS signals by performing the search using three separate parameters. These parameters include satellite number, Doppler information, and integration time. A block processing method of GPS signal processing is performed for particular in-view satellites over particular time intervals and for each of a set of hypothesized Doppler frequencies. Each parameter is optimized such that the GPS signal acquisition operation for a location fix is performed in a short period of time.

Abstract: 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 server. 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.

Abstract: A combined GPS and communication system having shared circuitry. The combined system includes an antenna for receiving data representative of GPS signals, a frequency converter coupled to the antenna, a frequency synthesizer coupled to the frequency converter, an analog to digital converter coupled to the frequency converter and a processor coupled to the frequency converter. The processor processes the data representative of GPS signals to determine a pseudorange based on the data representative of GPS signals. The integrated communication receiver includes a shared component which is at least one of the antenna, the frequency converter, the frequency synthesizer and the analog to digital converter. Typically, in certain embodiments the processor also demodulates communication signals received as well as controls the modulation of data to be transmitted as a communication signal through a communication link.

Abstract: A method and apparatus is disclosed for reducing cross-interference in a combined satellite positioning system receiver and communication transceiver device. A control signal is transmitted from the communication transceiver to the satellite positioning system receiver when the communication transceiver transmits data at a high power level over a communication link. The control signal causes satellite positioning system signals from satellites to be blocked from the receiving circuits of the satellite positioning system receiver, or to be disregarded by the processing circuits of the satellite positioning system receiver.

Abstract: A method and an apparatus for operating a satellite positioning system (SPS) receiver in a client/server architecture. In one example of a method, a first plurality of pseudoranges is determined at a first time and a second plurality of pseudoranges is determined at a second time which is after the first time. The first and the second pluralities of pseudoranges are stored. After the second time, the first and the second pluralities of pseudoranges are transmitted to a location server, normally in one transmission. The location server then determines a first position from the first plurality of pseudoranges and a second position from the second plurality of pseudoranges. In one particular example, the first and second pseudoranges are transmitted in response to a predetermined type of event, and the location server stores a collection of differential GPS data which has been collected over time.

Abstract: A global positioning system (GPS) receiver has first circuitry for receiving and processing pseudorandom sequences transmitted by a number of GPS satellites. The first circuitry is configured to perform conventional correlation operations on the received pseudorandom sequences to determine pseudoranges from the GPS receiver to the GPS satellites. The GPS receiver also includes second circuitry coupled to the first circuitry. The second circuitry is configured to receive and process the pseudorandom sequences during blockage conditions. The second circuitry processes the pseudorandom sequences by digitizing and stoning a predetermined record length of the received sequences and then performing fast convolution operations on the stored data to determine the pseudoranges. The GPS receiver may have a common circuitry for receiving GPS signals from in view satellites and downconverting the RF frequency of the received GPS signals to an intermediate frequency (IF).

Abstract: 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.

Abstract: A method and apparatus for measuring time related to satellite data messages which are used with satellite positioning systems (SPS). In one method, a first record of at least a portion of a satellite data message is received at an entity, which is typically a basestation. The first record is compared with a second record of the satellite data message, where the first record and the second record overlap at least partially in time. Then a time is determined from this comparison, and this time indicates when the first record (or the source from which the first record was obtained) was received at a remote entity which is typically a mobile SPS receiver. Various other methods of the invention are described and various apparatuses of the invention are also described. The methods and apparatuses measure time of day using SPS signals without reading the satellite data messages which are transmitted as data within these signals.

Abstract: A positioning sensor receives and stores a predetermined record length of positioning signals while in a fix position located such that the positioning sensor can receive positioning signals. Thereafter, the stored positioning signals are processed to determine the geographic location of the fix position. The fix position may correspond to a location of an object of interest or it may be in a known location relative to the position of the object, in which case once the geographic location of the fix position has been computed, the geographic location of the object can be derived. The positioning sensor includes a Snapshot GPS receiver which may collect and process GPS signals transmitted by GPS satellites using fast convolution operations to compute pseudoranges from the GPS satellites to the fix position. Alternatively, these computations may be performed at a basestation. The computed pseudoranges may then used to determine the geographic location of the fix position.

Abstract: A combined GPS and communication system having shared circuitry. The combined system includes an antenna for receiving data representative of GPS signals, a frequency converter coupled to the antenna, a frequency synthesizer coupled to the frequency converter, an analog to digital converter coupled to the frequency converter and a processor coupled to the frequency converter. The processor processes the data representative of GPS signals to determine a pseudorange based on the data representative of GPS signals. The integrated communication receiver includes a shared component which is at least one of the antenna, the frequency converter, the frequency synthesizer and the analog to digital converter. Typically, in certain embodiments the processor also demodulates communication signals received as well as controls the modulation of data to be transmitted as a communication signal through a communication link.