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. The methods and apparatuses are suitable for situations in which the received signal level is too weak to allow reading of the satellite data messages.

Method and apparatus for satellite positioning system based time measurement

A method and apparatus for determining a position of a mobile satellite positioning system (SPS) receiver. In one example of a method, a cell object information is determined; this cell object information comprises at least one of a cell object location or a cell object identification. An altitude is determined from the cell object information which is selected based upon a cell site transmitter which is in wireless communication with a cell based communication system which is coupled to (and typically integrated with) the mobile SPS receiver. The position of the mobile SPS receiver is calculated using the altitude which is determined from the cell object information. In another example of a method, an altitude pseudomeasurement is determined from an estimate of an altitude of the mobile SPS receiver. This estimate of the altitude may be from a cell based information source in a cell based system or may be an average altitude of the area of radio coverage of a wireless base station in the non-cell based system. The altitude pseudomeasurement may be used as a redundant measurement with fault detection and isolation techniques to determine whether at least one pseudorange has a faulty condition. Alternatively (or in addition), a comparison of the estimated altitude to a calculated altitude determines a condition of at least one pseudorange between an SPS satellite and the mobile SPS receiver. In one embodiment of this example, the position is determined from a position solution algorithm, and if the condition is a first state (not a fault state) the at least one pseudorange is used in the position solution algorithm.

Method and system for using altitude information in a satellite positioning system

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

Method and apparatus are disclosed for accurately determining position from GPS satellites and received on a ship using observations of C/A code group delay, L1 band center frequency carrier phase, L1 band 5115 MHz implicit carrier phase, and L2 band 5115 MHz implicit carrier phase A precise measurement of the range to each satellite is made based upon the L1 center frequency carrier phase A correction for ionospheric effects is determined by simultaneous observation of the group delays of the wide bandwidth P code modulations in both the L1 and L2 bands These group delays are determined by measuring the phases of carrier waves implicit in the spread-spectrum signals received in both bands These carriers are reconstructed from both the L1 and L2 band signals from each satellite without using knowledge of the P code The unknown biases in the L1 center frequency carrier phase range measurements are determined from simultaneous, pseudorange measurements, with time averaging The instantaneous position of the antenna receiving these signals, and therefore the ship, may then be determined from the ranges so determined, with both the bias and the ionospheric effects having been eliminated Additional antennas are positioned on the ship and a seismic streamer towed by the ship to reject false signals, compensate for blockage of signals by the ship's structure, and determine the position of sensors in the streamer

Multi-antenna gas receiver for seismic survey vessels

A radio telecommunications system includes a number of satellites in low earth orbits Subscriber units communicate with the satellites A single subscriber unit communicates with a single satellite using electromagnetic signals so that a measurement processor can obtain Doppler component, propagation duration, and real time measurements of the signals A location processor converts these measurements into a geographic location with respect to the earth through an iterative process The location processor determines the accuracy required for each location determination, and performs only the number of iterations needed to meet the accuracy requirements A service processor determines which qualifications to apply to communication services offered by the system These qualifications are based on the subscriber unit's location

Radio telecommunications system and method with adaptive location determination convergence

An improved position measuring system for determining a vehicle's position by receiving radio waves emitted from satellites is shown. The system adopts successive approximation using a convergent computation, in which initially estimated values are computed.

Position measuring system

PURPOSE: To improve the reliability of the results of measurement by comparing a position measured by satellite navigation with the one assumed by a dead reckoning navigation instrument. CONSTITUTION: A position P 1 measured by a satellite navigation instrument 1, a DOP value that is the index of the deterioration of position measurement based on the location of a satellite used for the position measurement and an assumed position P 2 obtained by a dead reckoning navigation instrument 2 are inputted to an error tester 3. In the error tester 3, a standard deviation σcorresponding to the inputted DOP value is fetched from a standard deviation memory 4 and whether the position P 1 is present in a circle with a center located in the position P 2 and with a radius σ is tested. When the position P 1 exists in the above-mentioned circle, the position P 1 is recognized as correct and a position measuring instrument is changed over to the satellite navigation instrument 1 by a position measuring instrument changeover unit 5. When the position P 1 exists outside the above-mentioned circle, the position P 1 is judged as uncertain and the position measuring instrument is changed over to the dead reckoning navigation instrument 2. COPYRIGHT: (C)1987,JPO&Japio

Gps position measuring instrument

PURPOSE: To accurately calculate the absolute position of a vehicle even in a time zone reduced in the number of satellits, by operating a receiving position on the basis of the position and propagation delay time of a satellite, obtained by receiving the navigation data emitted at a predetermined time from the satellite to analyze the same, and the vector quantity of the movement quantity of a vehicle. CONSTITUTION: A receiving means 5 receives the navigation data emitted at a predetermined time from a satellite to analyze the position and propagation time of the satellite. An operation means 7 knows the positions and propagation delay times, which were analyzed by the receiving means of plural satellites and operates a receiving position. A vector detection means 9 detects the movement quantity of a vehicle as a vector quantity and a vector operation means 11 obtains the detection signal of the vector detection means 9 to calculate the vector quantity of the vehicle movement quantity. A composite operation means 13 knows not only the positions and propagation delay times of the satellites from the receiving means 7 so as to provide a time interval but also the vector quantity of the movement quantity of the vehicle moved during this time from the vector quantity operation means 11 and operates the receiving position at a later time. COPYRIGHT: (C)1986,JPO&Japio

Position measuring apparatus for vehicle

PURPOSE: To take a measurement with higher accuracy by outputting a more reliable result between results of a radio wave navigation device and a dead reckoning navigation device and correcting the device with less reliability. CONSTITUTION: A position measuring instrument has the radio wave navigation device 1 which measures specific kinds of data on a position, an azimuth, a speed, etc., and a dead reckoning navigation device 2 which measures specific kinds of data on the position, azimuth, speed, etc., and is further provided with a reliability decision device 6 which inputs measurement data from both devices, decides which of both data have higher reliability, and outputs the more reliable measurement data and a calibrating device 7 which outputs calibration data to the device which outputs the less reliable data so that the device can outputs data nearly as reliable as the data that the more reliable device outputs. The dead reckoning navigation device 2 is equipped with an azimuth detector 4 and a range detector 5 and the azimuth detector 4 is composed of, for example, a terrestrial magnetic sensor and detects the traveling azimuth θI of a vehicle. Further, the range difference detector 5 outputs a unit pulse signal every time the vehicle travels by constant distance. COPYRIGHT: (C)1988,JPO&Japio

Hybrid type position measuring instrument

PURPOSE:To improve the reliability of the position and speed of a moving body by processing radio waves received from plural satellites into one-channel sequence data by a CPU, and measuring and comparing variation in offset from the frequency of a reference oscillation with a threshold value. CONSTITUTION:When a power source is turned on, the radio waves received by an antenna 1 from the plural satellites are amplified 2 and converted to the 1st IF by the reference oscillator 10 and a frequency synthesizer 9. The 1st IF is amplified 4 and converted 5 to the 2nd IF, which is amplified 6 and phase-compared 7 with the output of the frequency synthesizer 9. A dummy noise code is generated 13 wit the output of a CPU8 under the control of a dummy noise code period numeral control oscillator 14 to impose modulation 11 upon the output of a numeric control oscillator 12 for carrier phase synchronization, so that the output is inputted to the 2nd frequency converter 5. A double loop from the CPU8 back to the CPU8 is formed eventually to track a carrier in series to calculate whether the offset of the frequency is large or small. Consequently, the reliability of the position and speed of the moving body is decided.

Hideo Takai

Papers

Position measuring system

Gps position measuring instrument

Position measuring apparatus for vehicle

Hybrid type position measuring instrument

Satellite navigation system