JPH1020015A - Gps receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a rise time to a positioning calculation when orbital information of a satellite or a time of a receiver is not accurate by using DGPS correction information in a GPS receiver used in a navigation system and the like. SOLUTION: A GPS receiver is provided with a wave detecting unit 12 possessing a plurality of channels, a positioning unit 13 computing a position on the basis of the position of a satellite and a transmission time, a DGPS receiving unit 16 receiving DPS information, and a clock unit 14 outputting the present time. If a satellite position in the sky cannot be computed because orbital information for the statellite is not found, because the present time in the clock unit is not reliable, or because a receiver approximate position is not clear, a satellite can be received quickly by means of a satellite selecting unit 15, which is provided in the GPS receiver and sets a satellite having DGPS correction information preferably in the channel as the satellite can be received in at least a bas station, time for a positioning calcuation can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a G
GPS (Global
Positioning System) A GP that can reliably scan satellites located in the sky even if the orbit information and current time of the satellites are not known.
It relates to the S receiver.

[0002]

2. Description of the Related Art The technology of a conventional GPS receiver will be described with reference to FIG. The GPS receiver is a system that can simultaneously receive radio waves from a plurality of satellites and calculate the absolute position on the earth by acquiring navigation messages (orbit information and time information) from artificial satellites. .

[0003] 24 GPS satellites are arranged in the sky, and about 6 to 10 satellites can always be received. GPS
When the receiver starts up, the clock section
Using the current time from 44 and the satellite orbit information of the navigation message stored in the satellite selection unit 45, the satellite position is calculated and can be received from the approximate receiver position also stored in the satellite selection unit 45. A satellite to be scanned is assigned to a specific satellite, and a scanning is performed by the detection unit 42, and a radio wave from the satellite is received to acquire a navigation message. The orbit information of the navigation message obtained by the detection unit 42 and the position obtained by the positioning unit 43 are newly stored in the satellite selection unit 45, and are used in the next satellite start-up calculation.

The positioning unit 43 calculates the transmission time of the received satellite, obtains the difference from the time of the receiver, and multiplies the speed of light to obtain the distance. This distance is called a pseudo distance because it includes a time error of the receiver. A circle having the pseudo-range as a radius centered on the position of the satellite is obtained for three or more satellites, and the intersection thereof can be calculated as the position of the receiver. The pseudo-range includes an error due to a propagation delay that cannot be completely corrected by the ionosphere and the atmosphere and an intentional deterioration in accuracy. Due to the influence of these errors, 1
The position can be obtained only with an accuracy of about 00 m.

However, these uncorrectable errors can be obtained by obtaining the distance from the receiver to the satellite by receiving the satellite at a known position (base station). Therefore, the difference between the obtained distance and the propagation distance must be calculated. Can be calculated by The calculated error is transmitted as correction information, and the mobile unit (mobile station) receives the correction information and corrects the pseudo distance, thereby realizing accuracy of several meters. This system is generally referred to as DGPS (Differential
GPS), and DGPS correction information is received by DGPS
The receiving unit 46.

[0006] In a GPS receiver, if there is satellite orbit information, the current time, and the approximate position of the receiver, the arrangement of satellites in the sky can be calculated, satellites that can be received are set as channels, and scanning is performed. By doing so, it is possible to receive the satellite promptly. As a result, the rise time of the positioning calculation can be reduced.

[0007]

However, if even one of the elements for calculating the arrangement of the satellites is missing, it is not possible to select receivable satellites, so that the satellites are sequentially arranged one by one. Scanning was performed by assigning to channels.
Therefore, by the time three or more satellites are received and positioning is calculated,
Sometimes it took time.

In addition, if any one of the elements for calculating the arrangement of satellites has abnormal data, a satellite different from the satellite actually existing in the sky is set as a channel.
In some cases, satellites could not be received.

Even when the pseudorange is corrected using the DGPS correction information, if there is any abnormality in the measured pseudorange or in the calculated satellite position data, the positioning result will be abnormal data. Was.

[0010]

In order to solve the above-mentioned problem, a GPS receiver according to the present invention sets a satellite which can be received by a base station creating DGPS correction information to a channel with priority. Accordingly, even when the orbit information and the current time of the satellite are not known, it is possible to reliably scan the satellite arranged in the sky, and to shorten the time until the satellite is received.

[0011] Further, a combination of the satellite arrangement in the sky calculated by the receiver and the effective DGPS transmitted from the base station.
By comparing with the combination of satellites of the correction information, it is possible to detect the abnormality of the element used for the satellite arrangement calculation,
Recovery from an abnormal state where satellites cannot be received can be accelerated.

Further, using the positioning calculation result, the distance to the satellite is calculated backward, and the difference between the distance and the pseudo distance is calculated.
Compare with the correction value sent in the S correction information, if the result is significantly different, determine that the positioning result is abnormal,
It is possible to quickly return to a normal positioning state.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION
In a GPS receiver including: a detection unit having a plurality of channels; a positioning unit that calculates a position from a satellite position and a propagation time; a DGPS reception unit that receives DGPS information; and a clock unit that outputs a current time. When satellite orbit information is not available, or the current time is unreliable, or the position of the receiver is uncertain, the satellite constellation on the sky cannot be calculated due to reasons such as the correction information sent from the DGPS information. Priority is given to the enabled satellites as channels, and the satellites that are in the sky are reliably scanned, so it is possible to reduce the rise time from receiving the satellites to performing positioning calculations. Has the effect of being able to.

According to a second aspect of the present invention, a DGPS
2. The GPS receiver according to claim 1, wherein the satellite orbit information, the approximate position of the receiver, and the abnormality of the receiver clock used in the calculation of the satellite arrangement on the sky are detected from the correction information. Even if a non-existent satellite in the sky is set as a channel, it is possible to quickly recover from the abnormal state.

According to a third aspect of the present invention, the DGPS correction value is back calculated based on the calculated positioning result, and is compared with the correction value transmitted as DGPS information from the base station. The GPS receiver according to claim 1, further comprising a positioning abnormality determination unit for detecting, and has an operation of quickly recovering from an abnormal state of the positioning calculation.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 shows a GP according to the present invention.
1 shows a configuration of an S receiver, and according to FIG.
An antenna 11 for receiving a satellite signal, a detector 12 for demodulating the received signal to obtain a navigation message, and a detector 12
A positioning unit 13 for calculating the position of the receiver based on the navigation message demodulated in step 1, a DGPS receiving unit 16 for receiving correction information for calculating the position of the receiver by the positioning unit 13, and a current time of the receiver. And a satellite selection unit 15 for setting a satellite to be scanned on a channel.

At the time of start-up, the satellite selection unit 15 calculates the satellite arrangement in the sky from the stored orbit information, the approximate position of the receiver, and the current time of the clock unit 14, selects a receivable satellite, and sets it to a channel. Set.

When the satellite is received by the detection unit 12 and the navigation message is acquired, and the position of the receiver is updated by the positioning unit 13, the satellite selection unit 15 newly stores the orbit information and the position and stores it at the next start-up. Used for satellite constellation calculation. If any of these elements for calculating the satellite arrangement in the sky is missing, the satellite arrangement cannot be calculated.

By the way, the pseudo-range correction information received by the DGPS receiving unit 16 is not transmitted for all satellites, but is transmitted only for satellites whose correction values can be calculated in the base station. That is, an effective correction value is transmitted only for a satellite that can be received by the base station. Since the base station and the mobile station are several hundred kilometers apart, the satellite constellations can be said to be almost the same. Therefore, if the satellite constellation cannot be calculated without knowing any one of the satellite orbit information, the current time, and the receiver position, the satellite to which valid DGPS correction information is sent is preferentially set as a channel. , Satellites located in the sky can be reliably scanned. As a result, it is possible to receive the satellite quickly, and it is possible to shorten the rise time until the positioning calculation.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
The configuration of the GPS receiver according to the embodiment of FIG.
26 to 26 have the same configuration as the first embodiment, and the description of the configuration will be omitted. In order to determine a satellite to be set as a channel, the satellite selection unit 25 first calculates the positions of all satellites using the current time of the clock unit 24 and the orbit information of the satellite.
Thereafter, the elevation angle of each satellite is calculated using the approximate position of the receiver, and a satellite having a positive elevation angle, that is, a satellite existing in the sky, can be specified. By setting the specified satellite for each channel, satellites can be received quickly.

As described in the first embodiment, since the base station and the mobile station are several hundred kilometers apart from each other, it can be assumed that the satellite arrangement on the sky is the same. Therefore, the combination of the satellites of the valid DGPS correction information sent from the base station matches the combination of the satellites in the sky calculated by the satellite selection unit 25. Therefore, the satellite arrangement abnormality detection unit 27 compares the combinations of the satellites and, when it is determined that they are clearly different, determines one of the “current time”, “satellite orbit information”, and “the approximate position of the receiver” used in the satellite arrangement calculation. By determining that at least one is abnormal, it is possible to quickly recover from an abnormal state in which a satellite that cannot be received is set as a channel.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
Shows the configuration of the GPS receiver according to the embodiment of FIG.
36 are the same as those in the first embodiment, and a description of the configuration will be omitted. The base station that calculates the DGPS correction information can calculate the distance to the satellite because its position is known. Assuming that the obtained distance is the true distance, an error included in the propagation time can be calculated by taking the difference from the propagation distance obtained by actually receiving the radio wave. In the positioning abnormality determination unit 38, as in the base station, the positioning result obtained by the positioning unit 33 is assumed to be the true position, the distance to the satellite is obtained, the difference between the distance and the propagation distance is obtained, and the error is calculated. calculate. If the positioning result is correct, the error in the calculated propagation time is almost the same as that obtained in the base station. However, when the values do not match, the positioning calculation result can be determined to be abnormal.

As a method of abnormality determination, for example, if even one of the satellites used in the positioning calculation has a difference of a certain distance or more (for example, 300 m), the positioning result can be determined to be abnormal. . Alternatively, there is a method in which the difference between the propagation time error and the DGPS information for all channels is determined, and when the average value is equal to or more than a certain value (for example, 100 m), the positioning result is determined to be abnormal.

Further, when an abnormality is detected, for example, the positioning result is invalidated and is not output to the outside. Alternatively, by performing positioning calculation by changing the combination of satellites one by one and performing the same positioning abnormality determination, it is possible to identify the abnormal satellite, and quickly recover from the abnormal state of the positioning result. it can.

[0026]

As described above, according to the present invention, even when the satellite arrangement on the sky cannot be calculated, the satellite to be set to the channel is determined by using the valid satellite of the DGPS correction information, so that the start-up can be performed. An excellent effect that time can be shortened is obtained.

Also, by comparing the satellite arrangement on the sky with the DGPS correction information, it is possible to detect an abnormality in the data used for calculating the satellite arrangement and to quickly recover from the abnormal state. Is obtained.

Also, using the positioning calculation result, the error of the satellite propagation time is calculated backward, the abnormality is detected in the positioning result by comparing with the DGPS correction information, and an excellent effect that it is possible to quickly return from the abnormal state can be obtained. Is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a GPS receiver according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram of a GPS receiver according to a second embodiment of the present invention;

FIG. 3 is a schematic diagram of a GPS receiver according to a third embodiment of the present invention;

FIG. 4 is a schematic diagram of a conventional GPS receiver.

[Explanation of symbols]

 11, 21, 31, 41 Antenna 12, 22, 32, 42 Detection unit 13, 23, 33, 43 Positioning unit 14, 24, 34, 44 Clock unit 15, 25, 35, 45 Satellite selection unit 16, 26, 36 , 46 DPGS receiver 27 Satellite positioning error detector 38 Positioning error detector

Claims (3)

[Claims] 1. A detection unit having a plurality of channels, a positioning unit for calculating a position from a satellite position and a propagation time, and a DGP
In a GPS receiver including a DGPS receiving unit for receiving S information and a clock unit for outputting the current time, there is no orbit information of the satellite, or the current time cannot be trusted, or the position of the receiver is indeterminate. If the satellite arrangement on the sky cannot be calculated for the reason described above, a satellite selection unit for setting a channel in which the correction information sent from the DGPS information is valid is preferentially set to a channel is provided. GPS receiver. 2. The apparatus according to claim 1, further comprising a satellite arrangement abnormality detecting unit which can detect satellite orbit information used for calculating the arrangement of the satellites in the sky, an approximate position of the receiver, and an abnormality in the clock of the receiver from the DGPS correction information. The GPS receiver according to claim 1, wherein 3. A positioning abnormality determination unit that calculates a DGPS correction value based on the calculated positioning result, compares the calculated value with a correction value transmitted as DGPS information from a base station, and detects an abnormality in the positioning result. The G according to claim 1, wherein
PS receiver.