A positioning method, which is related to a technique to measure a correct position of a terminal by preventing time required for the position measurement, of calculating a position of a receiver according to signals from a plurality of wireless transmitters includes a first step of measuring propagation delay time of the signal from each of the wireless transmitters and calculating a position of the receiver and a standard deviation about measuring distance error, a second step of calculating a positioning error of the receiver a third step of determining, according to the positioning error calculated by the second step, wireless transmitters in directions nearer to a direction in which the positioning error is large, and a fourth step of re-detecting signals from the wireless transmitters determined by the third step and thereby re-calculating the position of the receiver.

Location detection method, location detection system and location detection program

A trace display apparatus for a navigation system is provided to make it easy to grasp the change in altitude traces of a mobile body from a starting point to an end point. The apparatus receives radio waves from GPS artificial satellites to measure the spatial position of the mobile body. The three-dimensional data (latitude, longitude and altitude) of a measuring point on the traces are calculated by a processing device and then stored in a storage device. The moving traces of an automobile are obtained by displaying the map data and the two-dimensional position data (latitude and longitude) from the starting point to the end point out of the stored three-dimensional data. The altitudes in the data for the measuring points and the distances from the starting point to measuring points, which are calculated from the latitude, and longitude, are indicated on a graph. Adjacent measuring points on the graph are connected to each other by a straight line, whereby the change in altitude is able to be displayed continuously.

Trace display apparatus for a navigation system

A portable, handheld electronic navigation device includes an altimeter and a GPS unit. An internal memory stores cartographic data, for displaying the cartographic data on a display of the navigation device. Accordingly, the device is capable of displaying cartographic data surrounding a location of the unit as determined by GPS and altitude information as determined by the barometric altimeter and GPS. The device provides an enhancement of the calibration and hence the accuracy of barometric altimeter measurements with the aid of derived altitudes from a GPS. The device is able to determine the need for calibration and perform the subsequent computations necessary to facilitate the calibration. Furthermore, the device is able to determine a correction quantity that should be applied to barometric altitude readings, thereby allowing the device to be calibrated while in motion. Both of these features ultimately result in a more accurate determination of altitude. In accordance with an aspect of the invention, the altimeter of the navigation device may be calibrated with altitude information entered by a user, with altitude information obtained from the cartographic, with altitude information derived from GPS or with any combinations thereof.

Device and method for calibrating and improving the accuracy of barometric altimeters with GPS-derived altitudes

In a vehicle location detecting system having a self-contained type location detecting section for determining the accumulation type location data, a satellite navigation type location detecting section for determining the satellite type location data from satellite navigation data, a synthesizing section calculates synthetic location data from the accumulation type location data and the satellite navigation type location data. An on-road location determining section determines an on-road location of the vehicle in accordance with the synthetic location data and road map data stored in a road map memory. A display sectin displays the on-road location determined by the on-road location determining section.

Vehicle navigation system

An vehicle position and azimuth computing apparatus is constructed to correct both of a positional error and an azimuth error caused by the accumulation of a sensor error and a map error and to provide both high positional precision and high azimuth precision. To this end, the vehicle position and azimuth computing apparatus operates to detect both an angular velocity and a moving distance of a vehicle, to compute an on-vehicle position and on-vehicle azimuth, and to detet a straight running condition of the vehicle. Then, after the GPS measurement positions during the straight running of the vehicle have been obtained, regression lines are obtained by regressing the longitudes and latitudes of the measurement positions during the straight running of the vehicle to the moving distance from the straight running starting position of the vehicle. Both of a vehicle position and a vehicle azimuth are computed based on the regression lines during the straight running of the vehicle, and then an on-vehicle position and an on-vehicle azimuth, which have been computed based on the detected values of the angular velocity and the moving distance of the vehicle, are modified by using the vehicle position and azimuth obtained based on the GPS measurement data.

Vehicle position and azimuth computing 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 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.

Satellite navigation system

PURPOSE: To give continuity between both a measurement position obtained by satellite navigation and a measurement position obtained by dead reckoning navigation by finding the weighted mean value of both measurement positions. CONSTITUTION: A satellite signal sent from an antenna 1 is demodulated by a reception part 2 and the dummy distance of a satellite is measured. Then, navigation message data and dummy distance data on the satellite from the reception part 2 are sent to an arithmetic processing part 3 to calculate the position of an automobile 10. An assumed position arithmetic part 7 calculates the assumed position of the automobile 10 from azimuth data on the automobile 10 detected by a magnetic goniometer 8 and run distance data detected by a range finder 9. A measurement position data calibration part 6 finds the weighted mean value of said two measurement positions by using the signal level of the receiving satellite and a geometric accuracy dispersed value sent from a control part 4 as parameters and then outputs the mean value to a position display operation part 5. COPYRIGHT: (C)1988,JPO&Japio

Data processing system for hybrid satellite navigation

PURPOSE:To display the accurate position of a vehicle by assuming artificially satellite when the arrival of a radio wave from one of three artificial satellites is stopped. CONSTITUTION:When there are three receivable satellites, a reception position computing element 22 calculates both data, i.e. tracks from signal lines 20a and 20b and pseudo distance and the reception position of the vehicle 10 is displayed 24. If one of the satellite is made unreceivable because of the presence of a shield, the position of the vehicle 10 at the position is regarded as a pseudo satellite and azimuth and distance data from a magnetic goniometer 14 and a distance meter 16 are inputted to a pseudo computing element 26. On the other hand, measured position data on the vehicle 10 at the time t1 is sent to the computing element 26 as position information on a pseudo satellite and the pseudo distance data on the pseudo satellite obtained by processing said azimuth and distance data is sent to the computing element 22. The computing element 22 computes the measured position of the vehicle 10 on the basis of received data from receivable satellites at the current time t2 from a receiver 18, i.e. pseudo distance and satellite position data, the pseudo distance of the pseudo satellite of the computing element 26, and the position of the pseudo satellite of the device 2, so that the measured position is displayed 24.

Yamaoka Noboru

Papers

Gps position measuring instrument

Hybrid type position measuring instrument

Satellite navigation system

Data processing system for hybrid satellite navigation

Navigation system for automobile