JPH05142327A - Portable gps receiver - Google Patents

Abstract

PURPOSE:To catch and track a satellite suitable for the position survey in a short time when transformation of a coordinate system is ordered, by setting a satellite selecting means which predicts the course of the satellite to select the satellite suitable for the position survey. CONSTITUTION:When a survey position is moved to an area where a coordinate system which is different from the former one should be used, an user inputs 6 the name or the number of the new coordinate system into an arithmetic unit 2 for making a coordinate system modification means 2d output the name or the number of the new coordinate system to a coordinate transformation means 2b and output the specific longitude and latitude of the area where the new coordinate system should be used to a memory means 3 to modify the output result of the former position survey. Under these conditions, a satellite selecting means 2c selects a satellite suitable for the position survey before the start of the position survey and sends information to a satellite signal receiving part 1. In this constitution, if a survey position is moved to a long distance from the former position, or the power supply is cut off when a survey position is moved to a long distance from the former position, a waste of processing time for an unsuitable satellite can be eliminated and a suitable satellite can be acquired and tracked instantaneously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an independent positioning GPS receiver for position measurement using GPS satellites, and more particularly to a portable GPS which is highly likely to be carried and to perform positioning at a point greatly different from the previously measured position. It concerns the receiver.

[0002]

2. Description of the Related Art Conventionally, a GPS receiver of a single positioning type has been known, which independently receives radio waves from GPS satellites to measure the current position, and is portable as the usage expands and miniaturization technology advances. GPS receivers are emerging.

A conventional GPS receiver will be described below. FIG. 2 is a block diagram of a conventional GPS receiver.

In FIG. 2, reference numeral 1 denotes a satellite signal which demodulates modulated radio wave signals from a plurality of satellites and outputs satellite position information, radio wave propagation time, and general orbit outline information (hereinafter referred to as almanac) to the arithmetic unit 2. The receiving unit 2 is a computing device.

The arithmetic unit 2 comprises a position calculating means 2a, a coordinate converting means 2b and a satellite selecting means 2c. The position calculating means 2a calculates a positioning position from a plurality of pieces of satellite position information from the satellite signal receiving section 1 and the radio wave propagation time, and the coordinate converting means 2a.
It is output to the memory means 3 as well as to b. The coordinate conversion means 2b corrects the position positioning result input from the position calculation means 2a to the coordinates (latitude / longitude) of the map of the use area and outputs it to the display device 5. The satellite selecting means 2c reads out the last measured position and almanac from the memory means 3,
The time is read from the clock device 4, the satellite arrival is predicted, and the receiving satellite is selected.

A memory means 3 receives and stores the positioning result and almanac from the position calculating means 2a, and outputs the stored positioning result and almanac before a predetermined time to the satellite selecting means 2c. It is a clock device that measures the time even when the power is turned on, and indicates the approximate time for predicting the arrival of a satellite. Reference numeral 5 indicates the current positioning position and the like input from the coordinate conversion means 2b as C
A display device 6 is displayed on the RT or the like, and 6 is an input means by which the user can input the destination, the coordinate system to be used, and the like. The operation of the GPS receiver configured as above will be described below.

The principle of positioning by GPS is as follows. The GPS satellite has a standard clock called a GPS clock, which always keeps the standard time, and when transmitting radio waves, the transmission time information at that time is added to the transmission signal. GP
The S receiver can determine the propagation time of the radio wave between the transmitting and receiving points by measuring the difference between the transmission time sent from the satellite and the time at the time of reception. The distance of can be calculated.

Further, the GPS satellite constantly calculates its own position and carries the calculated position information on the transmission signal. If the propagation time of the radio wave is measured at the reception point, the measurement point at that time is located on a spherical surface having a certain radius (distance obtained from the propagation time) centered on the satellite. If this is performed for three satellites, the measurement position can be obtained as an intersection of three spherical surfaces centered on each of the three satellites.

However, synchronizing the clock of the receiving point with the clock of the satellite is technically problematic and disadvantageous in reducing the cost of the receiver. To solve this problem, the number of satellites received is increased by one.

At the receiving point, signals from 4 satellites are received and 3
The position of the reception point can be obtained by solving a simultaneous equation in which four unknowns are the coordinate of the direction, the satellite and the clock error of the reception period. If the height of the measurement point is known, 3
Positions can be determined by receiving signals from a single satellite.
However, in order to smoothly switch the receiving satellite when the GPS satellite, which is a mobile satellite, disappears from the field of view or when the radio waves are blocked by an obstacle such as a building, the receiver usually has a spare satellite signal receiving circuit. Have more than 5 satellites and receive satellite signals at the same time.

The satellite signal receiving unit 1 measures the satellite position information and the radio wave transmission time for position positioning broadcast by a plurality of satellites, and also outputs the radio wave propagation time to the position calculation means 2a, and outputs an outline of all the satellites. The almanac which is the orbit information is output to the satellite selecting means 2c. The position calculation means 2a calculates a position to be measured based on the four or three pieces of satellite position information from the satellite signal receiving section 1 and the propagation time of the radio wave. Also,
The positioning result of the current position obtained by calculation is used as the coordinate conversion means 2
In addition to outputting to b, the positioning result and the time thereof are output and stored in the memory means 3 in some cases.

The coordinate conversion means 2b performs conversion calculation of the position positioning result input from the position calculation means 2a into latitude / longitude of the coordinate system instructed and input by the user by the input means 6 and outputs the result to the display device 5 for display. .. Here, the selection of the satellite to be received by the satellite signal receiving unit 1 is in accordance with the instruction of the satellite selecting means 2b.

The satellite signal selecting means 2b reads out the approximate time data from the clock means 4 when the power is turned on, reads out the previous positioning position result and the almanac which is the rough orbit information of all satellites from the memory means 3, and reads the previous positioning position. The satellite arrival prediction calculation at the time indicated by the clock means 4 is performed using almanac to predict the receivable satellites, and the satellite position calculation in which the positioning position calculation error is smaller than the approximate calculation position of each receivable satellite Then, the receiving satellite is determined and the receiving satellite number is output to the satellite signal receiving unit 1. This satellite selection method is not a problem because the stationary GPS receiver hardly moves when the power is cut off.

[0014]

However, in the above-mentioned conventional configuration, the position of the portable GPS receiver often moves when the power is cut off, and if the positioning position largely changes from the previous positioning position, it cannot be captured. There was also a problem that it would take a long time to capture satellites because it would try to input information for the satellites. In addition, in some cases, it may take longer than when Almanac is not owned, and battery consumption, which is a portable power source, is heavy and unreasonable.

[0015]

In order to solve the above-mentioned problems, the present invention normally selects a satellite by the above-mentioned conventional method, and when a user issues a coordinate system conversion command,
At that time, the positioning device performs satellite landing prediction on the assumption that it is located in the area using the newly input coordinate system,
Satellite selection means is provided for selecting a satellite suitable for positioning based on the result of the satellite arrival prediction.

[0016]

According to the present invention, according to the above-described structure, even if the device is largely moved in a power-off state, the coordinate system conversion command issued by the user inputs the approximate position of the positioning device at that time to the device. Then, the satellite selection means selects a satellite suitable for positioning in a short time based on the information,
Can capture satellites.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a portable GP according to an embodiment of the present invention.
It is a block diagram of an S receiver.

In FIG. 1, reference numeral 1 is a satellite signal receiving section for demodulating modulated radio wave signals from a plurality of satellites and outputting satellite position information, radio wave propagation time and almanac to a computing device 2. Reference numeral 2 is a computing device. Position calculating means 2a for calculating a positioning position from a plurality of satellite position information from the signal receiving section 1 and radio wave propagation time, outputting it to the coordinate converting means 2b and outputting it to the memory means 3, and position input from the position calculating means 2a. The coordinate conversion means 2b that corrects the positioning result to the latitude and longitude of the map of the area of use and outputs it to the display device 5, and the previously measured position and almanac are read from the memory means 3, the time is read from the clock device 4, and the satellite It is composed of satellite selecting means 2c which makes a flight prediction and selects a receiving satellite.

Reference numeral 3 is a memory means for inputting and storing the positioning result and almanac from the position calculating means 2a and outputting the stored positioning result and almanac before a given time to the satellite selecting means 2c. Reference numeral 4 denotes a timepiece device that measures the time by a backup power source even during a power failure and indicates the approximate time for predicting the arrival of a satellite when the power source starts up. Reference numeral 5 is a display device for displaying the current positioning position or the like input from the coordinate conversion means 2b on a CRT or the like, and reference numeral 6 is an input means for allowing the user to input a destination, a coordinate system to be used and the like. The above-mentioned means are the same as the configuration of the conventional example shown in FIG. 2, so the same reference numerals are given and detailed description thereof is omitted.

Reference numeral 2d is a coordinate system changing means provided in the arithmetic unit 2. When the coordinate system change instruction and the coordinate system name or the coordinate system number to be changed are input from the input unit 6, the coordinate system changing unit 2d converts the previously measured position data stored in the memory unit 3 into specific position data. change.

The operation of the portable GPS receiver configured as described above will be described below.

When the change of the coordinate system is not inputted from the input means 6 before the positioning is started, the satellite selecting means 2c of the arithmetic unit 2 stores the last positioning position result and the almanac from the memory means 3 as in the conventional example. It is read out, the current approximate time is read from the timepiece device 4, and it is assumed that the user is in the same area as when the last positioning was performed, the satellite arrival prediction and the satellite constellation calculation at the time read out from the timepiece device are performed, and at that time The satellite signal receiving unit 1 is notified of the numbers of a plurality of satellites suitable for positioning.

The satellite signal receiving section 1 captures and tracks the radio waves of a plurality of satellites designated by the satellite selecting means 2c, and satellite position information / radio wave transmission time for position positioning broadcast by the satellites and propagation time of the radio waves. Is measured and output to the position calculating means 2a of the arithmetic unit 2 and the almanac is output to the satellite selecting means 2c of the arithmetic unit 2.

The position calculation means 2a calculates the positioning position in the coordinate system of the WGS 84 based on the four or three satellite position information from the satellite signal receiving unit 1 and the propagation time of its radio wave, and calculates the latitude and longitude of the positioning position result. Coordinate conversion means 2b of device 2
At the same time, the positioning result and the time thereof are output and stored in the memory means 3 in some cases.

The coordinate conversion means 2b receives the position measurement result of the WGS84 coordinate system input from the position calculation means 2a, and the latitude / coordinate of the coordinate system designated by the user through the input means 6.
The longitude is changed and output to the output device 5 for display.

Here, when the user moves the portable GPS receiver to an area where a coordinate system different from the current one is used, the user inputs a new coordinate system name or number to the arithmetic unit 2 by the input means 6. To do. The coordinate system changing means 2d of the arithmetic unit 2 outputs the name or number of the new coordinate system to the coordinate converting means 2b, and outputs and stores the specific latitude / longitude of the area using the new coordinate system to the memory means 3. Change the last positioning result.

In this state, the satellite selecting means 2 before positioning is started.
c selects a satellite suitable for positioning and notifies the satellite signal receiving unit 1 of it. As a result, if the positioning position changes significantly from the previous positioning position, the unnecessary processing time for satellites that are not suitable for use (for example, hidden ones) can be omitted, and satellite acquisition and tracking can be performed instantly. ..

[0028]

As described above, the present invention has an effect that the satellite can be instantaneously captured even when it is moved largely from the previous positioning position in the power-off state.

[Brief description of drawings]

FIG. 1 is a block diagram of a portable GPS receiver according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional portable GPS receiver.

[Explanation of symbols]

 1 satellite signal receiving unit 2 arithmetic unit 2a position calculating unit 2b coordinate converting unit 2c satellite selecting unit 2d coordinate system changing unit 3 memory unit 4 clock unit 5 display unit 6 input unit

Claims (1)

[Claims] 1. A GPS satellite-based positioning means for demodulating a radio wave signal from a GPS satellite to measure a current position and a current time, all satellite orbit outline information received by the GPS satellite-based positioning means, and the GPS satellite usage. Memory means for storing the position information measured by the positioning means, coordinate conversion means for converting the coordinates of the positioning result into the coordinate system of the region in which it is used,
A coordinate system including a coordinate system input means for instructing a coordinate system to be used and a clock means, and when a coordinate system change is input from the coordinate system input means at the time of starting positioning, the coordinate system in which the measurement position at that time is newly input A portable GPS receiver, characterized in that it is provided with a receiving satellite selecting means for selecting a satellite suitable for reception from the information and almanac stored in the memory means on the assumption that the area is in use.