JPH08285933A - Gps receiver - Google Patents

Abstract

PURPOSE: To obtain a GPS receiver which can start a positioning computation quickly even when the RTC and the stored data of the receiver are wrong. CONSTITUTION: The radio waves of a satellite are demodulated in a detection part 2, and the position and the speed of a receiver are found in a positioning part 3 on the basis of a collected navigation message or the like. In a tracking satellite selection part 6, the position of the satellite is found on the basis of orbit information on a satellite stored in a storage part 4 and on the basis of the present time of an RTC 5, a visible satellite is judged on the basis of the position of the receiver, and a satellite to be tracked is decided in the detection part 2. At this time, at least one channel of the detection part 2 is scanned at random, satellites other than the satellite selected in the tracking satellite selection part 6 are received, and a correct time is obtained on the basis of time information on the satellite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a GPS that orbits the earth.
GPS (Global Posi) that calculates receiver position and speed from satellite
tioning System) receiver.

[0002]

2. Description of the Related Art A GPS receiver receives radio waves from a plurality of satellites and obtains navigation messages (orbit information and time information) from artificial satellites to determine the absolute position on the earth and the Doppler shift frequency. It is a system that can calculate the speed by measuring.

A conventional GPS receiver will be described below with reference to the drawings. In FIG. 3, reference numeral 1 denotes an antenna that receives radio waves from satellites, and 2 demodulates the radio waves received by the antenna 1 to obtain a navigation message, time information, etc.
It is a detection unit that outputs to. The positioning unit 3 establishes a simultaneous equation from the position of the satellite and the propagation time of radio waves from the satellite to the receiver to determine the position of the receiver. GPS satellites were launched into six orbits at an altitude of 20,000 km of the earth,
Currently, a total of 25 satellites are in operation. The receiver can perform positioning calculation by simultaneously receiving at least three or more of these satellites. Therefore, the positioning calculation result and the navigation message are stored in the storage unit 4, and the tracking satellite selection unit 6 uses the current time of the RTC (Real Time Clock) 5 and the data of the storage unit 4 to determine the visible satellite of the current time. By making a determination and determining the satellite number to be set in the detection unit 2, it is possible to quickly receive satellites and speed up the start of positioning calculation without scanning unnecessary satellites.

[0004]

However, in the above configuration, in the unlikely event that the RTC fails or the information stored in the storage unit is incorrect, the satellite that cannot actually be received is selected by the tracking satellite selection unit. It is conceivable that the satellite will be selected and the satellite will not be able to be received forever.

The present invention solves such a problem, and GPS can quickly start positioning calculation even if the RTC or stored data of the receiver is incorrect.
The purpose is to provide a receiver.

[0006]

In order to achieve the above object, in the GPS receiver of the present invention, at least one or more channels out of a plurality of channels are any satellites other than the satellite selected by the tracking satellite selector. By scanning the satellite, the satellite is always received even if the RTC and the stored data are incorrect.

Further, an initial position abnormality detection unit for checking the validity of the initial position data of the receiver from the received satellite is provided, and if the data stored in the storage unit is invalid,
Randomly perform satellite scanning on all channels.

[0008]

According to the above construction, any satellite can be received without fail, and even if the RTC fails, the correct time can be obtained from the time information of the received satellite.

Further, when the initial position abnormality detecting unit detects an abnormality in the initial position data, random scanning is performed on all the channels so that the satellite can be received without being dragged by the initial position abnormality data. It is possible to shorten the start-up time of positioning calculation.

[0010]

Embodiments will be described in detail below with reference to the drawings. FIG. 1 shows the configuration of a GPS receiver according to the first embodiment of the present invention. In FIG. 1, 1 is GP
An antenna 2 for receiving radio waves from the S satellite is a detector having a plurality of channels, demodulates the spectrum-spread satellite radio waves, and collects navigation messages and satellite time information. 3 is a navigation message collected by the detection unit 2.
From the satellite position calculated from (orbit information) and the propagation time of the radio wave from the satellite to the receiver, make a simultaneous equation of (Equation 1),
It is a positioning unit that finds the position of the receiver by solving the simultaneous equations. Further, the positioning unit 3 can also calculate the speed from the Doppler shift frequency obtained by the detection unit 2.

[0011]

[Equation 1]

The storage unit 4 stores positioning results, satellite orbit information, and the like. The RTC 5 is a counter that represents the current time of the receiver. The tracking satellite selection unit 6 obtains the position of the satellite from the orbit information of the satellite stored in the storage unit and the current time of the RTC 5, and further determines the visible satellite from the position of the receiver stored in the storage unit 4, and the detection unit 2 Determine the satellite to track. At this time, at least one channel of the detection unit 2 is
The satellites not selected by the tracking satellite selection unit 6 are scanned. As a result, even if the RTC time is wrong, it is possible to receive at least one satellite without fail. Since accurate time information is transmitted from the satellite, the satellite in the visible range can be reliably set in the detection unit 2 by performing the calculation of the tracking satellite selection unit 6 again using the time obtained from the satellite, and the positioning calculation can be performed. The rise time of can be shortened.

Next, FIG. 2 shows a GPS receiver according to a second embodiment of the present invention, which differs from the configuration of FIG. 1 in that an initial position abnormality detecting section 7 is further provided. is there. The initial position abnormality detection unit 7 obtains the satellite position from the received accurate satellite time and orbit information, and recalculates the elevation angle of the satellite from the initial position of the receiver. If the initial position is correct, it is within the visible range because it is a received satellite. If it is outside the visible range, it is determined that the initial position is incorrect, and it is instructed to switch all channels of the detection unit 2 to random scanning. As a result, a new satellite can be received without being dragged to an incorrect initial position.

[0014]

As described above, according to the present invention,
By randomly scanning at least one channel among the detection units having a plurality of channels, the correct current time can be obtained and the rising time of positioning can be shortened.

Further, by providing an initial position abnormality detection unit, an abnormality in the stored initial position data can be detected quickly, all channels are switched to random scanning, the satellite scanning time is shortened, and the positioning start-up time is shortened. The effect of doing is obtained.

[Brief description of drawings]

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

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

FIG. 3 is a configuration diagram of a conventional GPS receiver.

[Explanation of symbols]

1 ... Antenna, 2 ... Detection section, 3 ... Positioning section,
4 ... Storage unit, 5 ... RTC, 6 ... Tracking satellite selection unit, 7 ... Initial position abnormality detection unit.

Claims (2)

[Claims] 1. A detection unit having a plurality of channels, and a positioning unit for performing positioning calculation from the position of a satellite and a radio wave propagation time,
It has a storage unit for storing positioning results and satellite orbit information, an RTC indicating the current time, a tracking satellite selection unit for selecting a satellite to be tracked from the storage unit information and the RTC, and at least one channel of the detection unit is randomly selected. A GPS receiver characterized by scanning and receiving one or more arbitrary satellites other than the satellite selected by the tracking satellite selection unit. 2. When an arbitrary satellite is received, the elevation angle of the satellite is calculated, and if the satellite is out of the visible range,
The GPS according to claim 1, further comprising an initial position abnormality detection unit that determines that the initial position of the receiver stored in the storage unit is invalid and instructs to switch all channels to random scanning. Receiving machine.