JPH07311254A - Satellite position measuring apparatus - Google Patents

Abstract

PURPOSE:To reduce power consumption while increasing the number of receiving channels which can be operated in parallel. CONSTITUTION:The supply of a reference clock to a receiving channel which is not used for acquisition and a tracking of a signal from a position measuring satellite of a plurality of receiving channels 21a, 21b,..., 21n for constituting signal tracking means 20 is interrupted by a reference clock controller 31. A satellite position measuring apparatus which has low power consumption despite a large number of the receiving channels which can be processed in parallel by increasing the number of the channels 21a, 21b,..., 21n can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to GPS (Global Position
ioning System), GLONASS (GlobalOrbiting N)
GNSS (Global Na
vigation Satellite System), and more particularly, to a satellite positioning device that constitutes these systems.

[0002]

2. Description of the Related Art GNSS such as GPS and GLONSS are available as means for measuring the position and speed of a moving body. In this type of system, a signal is transmitted from a predetermined number of positioning satellites operating in an orbit around the earth to a receiver (satellite positioning device) mounted on a mobile body on the earth or carried by a user. This signal is spread-spectrum-modulated by a pseudo noise code (PN code), and carries orbit data indicating the orbit of the positioning satellite and clock data indicating the value of the clock mounted on the positioning satellite.

The satellite positioning device selects at least the number of positioning satellites necessary for positioning calculation from among the positioning satellites in the orbit around the earth and in the currently visible state, and transmits from the selected positioning satellites. The signal is received and the navigation data (clock data, orbit data described above, etc.) is demodulated.

As a method of receiving and demodulating navigation data transmitted from a positioning satellite, for example, there is a method of arranging a plurality of receiving channels in parallel. That is, the number of reception channels required for the positioning calculation is provided, and the signals transmitted from different positioning satellites are received by the respective reception channels to demodulate the navigation data. The navigation data obtained by each reception channel is used for positioning calculation, and as a result of the positioning calculation, data such as the position and speed of the user is obtained. Obtained position,
The data such as speed is provided for display, for example.

[0005]

In such a configuration in which a plurality of receiving channels are arranged in parallel, the larger the number of receiving channels is, the more simultaneous positioning satellites are subjected to simultaneous reception and demodulation. You can However, if the number of reception channels is increased, the power consumption of the satellite positioning device will increase accordingly.

The present invention has been made to solve the above problems, and it is possible to selectively reduce the power consumption in each reception channel in a configuration in which a plurality of reception channels are arranged in parallel. Accordingly, it is an object of the present invention to reduce the power consumption of the satellite positioning device without reducing the number of positioning satellites that can be processed in parallel.

[0007]

In order to achieve such an object, a positioning satellite tracking device according to the present invention uses a signal from a positioning satellite to be tracked as a reference clock when a reference clock is given. A plurality of reception channels that output data necessary for positioning calculation by performing acquisition and tracking in synchronization with, and a reception channel that acquires and tracks signals from positioning satellites necessary for positioning calculation among the plurality of reception channels. Means for reducing the power consumption by other receiving channels by supplying the reference clock only to the receiver.

Further, the satellite positioning device according to the present invention obtains the necessary data from the reception channel for the selected positioning satellite, the positioning satellite tracking device according to the present invention, means for selecting the positioning satellite necessary for the positioning calculation. And a means for performing positioning calculation in the case of being detected.

[0009]

In the positioning satellite tracking device according to the present invention, a plurality of receiving channels are provided, and the tracking tracking of the signal from the positioning satellite is performed by each receiving channel. By this acquisition and tracking, data necessary for positioning calculation is output from each reception channel. The signal acquisition and tracking operation in each reception channel is performed in response to the supply of the reference clock. Here, in the present invention, only in the reception channel for capturing and tracking the signal from the positioning satellite necessary for the positioning calculation,
This reference clock is supplied. Therefore, depending on the reception channel that does not need to perform the acquisition and tracking operation among the plurality of reception channels described above, a large amount of power consumption due to the acquisition and tracking operation does not occur. Therefore, in the present invention, the power consumption of the device is reduced without reducing the maximum number of positioning satellites that can be acquired and tracked.

Further, in the satellite positioning device according to the present invention, first, the positioning satellites required for the positioning calculation are selected, for example, by evaluating the geometrical arrangement of each positioning satellite, and the reference clock is selectively supplied according to the result. The action is executed. When necessary data is obtained from the reception channel to which the reference clock is supplied, positioning calculation is performed based on this data, and the position and speed of the satellite positioning device (user) is output. Therefore, in the satellite positioning device according to the present invention, the above-mentioned reduction in power consumption is realized while suitably performing the positioning calculation.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a satellite positioning device according to an embodiment of the present invention. The apparatus shown in this figure comprises an antenna 10, a high frequency converter 11, an A / D converter 12, a signal tracking unit 20, a reference clock generator 30, a reference clock controller 31, a controller 40 and an output unit 50. ing.

A signal transmitted from a positioning satellite (not shown) is received by using the antenna 10 and the high frequency conversion means 11 is received.
Entered in. The high frequency conversion means 11 performs processing such as amplification and frequency conversion on the signal from the positioning satellite received using the antenna 10, and supplies the resulting analog signal to the A / D conversion means 12. A / D conversion means 12
Converts the analog signal supplied from the high frequency conversion means 11 into a digital signal and supplies the digital signal to the signal tracking means 20.

The signal tracking means 20 has a structure in which a plurality of receiving channels 21a, 21b, ... 21n are arranged in parallel. Each of the reception channels 21a, 21b, ... 21n has a PN code comparison unit 201 and a carrier comparison unit 20.
2, an adder 203, a PN code generator 204 and a carrier detection signal generator 205. In this figure, the reception channels 21b,
The contents of 21n are omitted.

Each receiving channel 21a, 21b ... 21n
From the reference clock generator 30 to the reference clock controller 3
1 operates according to a reference clock supplied via
Data necessary for positioning calculation, for example, data indicating the orbit of the positioning satellite is reproduced from the digital signal supplied from the / D conversion means 12 and supplied to the control unit 40. The control unit 40
Of the plurality of reception channels 21a, 21b ... 21n provided in the signal tracking means 20, a predetermined positioning calculation is performed based on the output from the reception channel that is tracking the signal from the positioning satellite necessary for the positioning calculation. I do. With this positioning calculation, the moving body equipped with the satellite positioning device shown in this figure, and the user carrying this device,
Information such as its position and speed can be obtained. The output means 50 is
It is means for outputting information such as position and speed obtained by the control unit 40, and has a configuration capable of image output, voice output, and the like.

Each receiving channel 21a, 21b ... 21n
Works in detail as follows.

First, the signal transmitted from the positioning satellite is spread spectrum modulated by a predetermined PN code. For example, in the case of GPS, different P for each positioning satellite
N code is given. The chip rate of the PN code is 1.023 MHz, one cycle is 1023 chips, and therefore the repetition cycle of the PN code is 1 msec. The signal transmitted from the positioning satellite carries navigation data having a rate of 50 bit / sec.

The PN code generator 204, the PN code comparing section 201 and the control section 40 form a synchronous loop for tracking and capturing the PN code. That is, the signal received from the positioning satellite and converted into a digital signal by the A / D conversion means 12 is first input to the PN code comparison unit 201 and compared with the PN code supplied from the PN code generator 204. The PN code generated by the PN code generator 204 is controlled by the control unit 40 to be a PN code corresponding to one of positioning satellites used for positioning calculation. PN supplied from the PN code generator 204
When the phase of the code does not match the phase of the PN code superimposed on the digital signal supplied from the A / D conversion means 12, the output of the PN code comparison unit 201 indicates that the correlation between the two is low. Becomes On the other hand, the phase of the PN code supplied from the PN code generator 204 and A
When the phase of the PN code superimposed on the digital signal supplied from the / D conversion means 12 matches,
Since the phase between the two is high, the spread spectrum modulation applied to the signal received from the positioning satellite is canceled (spread despread modulation). The control unit 40 uses the PN code generator 20.
P of the phase of the PN code generated by 4 is superimposed on the digital signal output from the A / D conversion means 12.
The PN code generator 20 so that it matches the phase of the N code.
4 controls the PN code generation phase.

The carrier detection signal generator 205, the carrier comparison section 202 and the control section 40 form a carrier synchronization loop. That is, the PN code comparison unit 201
When the frequency and phase of the carrier component included in the signal output from the carrier detection signal match the frequency and phase of the carrier detection signal generated by the carrier detection signal generator 205, the signal output from the carrier comparison unit 202. Is a signal from which the carrier used for transmission from the positioning satellite has been removed. The control unit 40 controls the frequency and the generation phase of the carrier detection signal in the carrier detection signal generator 205 so that such a condition is established.

The addition unit 203 adds the output of the carrier comparison unit 202 for the repetition period of the PN code, that is, 1 msec in the case of GPS. The data obtained, that is, the navigation data transmitted from the positioning satellites, is the control unit 40.
Is supplied to. When such navigation data is obtained for more than the number of positioning satellites required for positioning calculation, the control unit 40 uses the navigation data and information such as the control phase of the PN code in the PN code generator 204, The satellite position and pseudo-range of each positioning satellite are determined, and the position of the satellite positioning device is determined based on these. The control unit 40 also detects the Doppler shift based on the frequency of the carrier detection signal in the carrier detection signal generator 205 and the like, and obtains the moving speed of the satellite positioning device based on the detected Doppler shift.

The feature of this embodiment is that a plurality of receiving channels 21a, 21b ... 21n provided in the signal tracking means 20.
Is selectively operated or stopped by selectively supplying a reference clock, thereby realizing a satellite positioning device with low power consumption while increasing the maximum number of positioning satellites that can be received and processed.

The reference clock used as such means for selectively operating / stopping is generated in the reference clock generating section 30. The reference clock generating section 30 can be composed of, for example, a crystal oscillator or the like. The reference clock control unit 31 has a plurality of reception channels 21a, 21b ... In response to the control signal supplied from the control unit 40.
The reference clock is supplied to the required number of 21n. That is, the supply of the reference clock is cut off for the reception channels that are not necessary for the positioning calculation in the control unit 40.

Here, the receiving channels 21a, 21b ... 2
1n can be configured by, for example, a CMOS circuit, a flip-flop, or the like. As a characteristic of the CMOS circuit, the power consumption when the output value changes from L to H or from H to L rather than the power consumption (static power consumption) when the state value is constant (dynamic It is known that the power consumption is extremely high. It is also known that flip-flops also generate dynamic power consumption when a clock is supplied even if input data is constant. Therefore, if a plurality of receiving channels are provided and the reference clock is supplied to any of the receiving channels regardless of the signal input state to each receiving channel, the number of receiving channels is increased. As a result, power consumption increases. On the other hand, if the reference clock is not supplied to the reception channels that are not necessary for the positioning calculation as in the present embodiment, a satellite positioning device with a large number of reception channels and low power consumption can be obtained. be able to. For example, the receiving channels 21a, 21b ... 21n
Even if the number of is set to 8, the dynamic power consumption is not generated by all eight receiving channels,
Since the dynamic power consumption is generated only by the number of, for example, four reception channels selected by the control unit 40, it is possible to reduce the power consumption of the signal tracking unit 20, and thus the entire satellite positioning device. It should be noted that the reference clock control unit 31 may receive the reception channels 21a, 21b, ...
It can be configured by a switch provided corresponding to each n.

Although the above description has been made assuming GPS, the present invention is also applicable to GNSS other than GPS.

[0025]

As described above, according to the present invention,
Since the reference clock is supplied only to the receiving channel that captures and tracks the signal from the positioning satellite to reduce the power consumption by other receiving channels, a device with low power consumption is realized despite the large number of receiving channels. can do. Therefore, it is possible to increase power consumption while increasing the number of maximum reception channels that can be simultaneously processed in parallel.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a satellite positioning device according to an embodiment of the present invention.

[Explanation of symbols]

 20 signal tracking means 21a, 21b, ... 21n reception channel 30 reference clock generation section 31 reference clock control section 40 control section 50 output means 201 PN code comparison section 202 carrier comparison section 203 adder section 204 PN code generator 205 carrier detection signal generation vessel

Claims (2)

[Claims] 1. A plurality of receiving channels for outputting data necessary for positioning calculation by, when a reference clock is given, capturing and tracking a signal from a positioning satellite to be tracked in synchronization with the reference clock. And means for reducing the power consumption by other receiving channels by supplying the reference clock only to the receiving channel that captures and tracks the signal from the positioning satellite necessary for positioning calculation among the plurality of receiving channels. A positioning satellite tracking device, comprising: 2. The positioning satellite tracking device according to claim 1, means for selecting a positioning satellite required for positioning calculation, and positioning calculation when necessary data is obtained from a reception channel for the selected positioning satellite. A satellite positioning device comprising: