JP3427325B2 - GPS receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GPS receiver used in a navigation system or the like.

[0002]

2. Description of the Related Art A GPS (Global Positioning System) receiver receives a signal transmitted from a GPS satellite launched at 20,000 km above the sky, and based on the received information, the latitude, longitude and altitude. Is a device for measuring. Measuring the position of the receiving device in this way is called positioning. A total of 24 GPS satellites are arranged in six orbits, and positioning is performed based on the information of three or more satellites.

FIG. 4 is a block diagram showing the structure of a general GPS receiver. In FIG. 4, 1 is an antenna for receiving a signal from a GPS satellite, 2 is a frequency conversion unit for converting the frequency of the received signal so that it can be controlled, and 3 is a control for performing various controls such as positioning from the received signal. Department,
Reference numeral 4 is a display unit, and 5 is an operation unit.

Next, the operation of the conventional GPS receiver will be described. When the GPS receiving device performs positioning, it is necessary to first catch the satellite. This is called capture. If three or more satellites can be captured, positioning calculation is performed using signals from those satellites. Moreover, in order to perform the positioning calculation in real time, it is necessary to always chase the satellite once captured. This is called tracking. Further, various calculations such as speed calculation and display processing are performed based on the information calculated by positioning.

FIG. 5 shows an example of the control flow of a conventional GPS receiver. First, GPS satellites are captured (S
1). Then, after capturing three or more GPS satellites, positioning calculation is performed (S2). Further, tracking processing is performed so as not to let the GPS satellites escape (S3). The result of the tracking process is stored in the tracking information table (S4). The interval for performing the tracking process is every 10 ms (1/100 second). That is, the tracking process requires extremely high-speed repetitive processing. Further, of the time of 10 ms, the time required for the tracking processing is about 70%. Other processing such as positioning calculation is performed using the remaining 30% of the time. The positioning result is stored in the positioning information table (S5) and displayed (S6).

[0006]

As described above, in the GPS receiver, high-speed processing is required for tracking processing. Then, conventionally, other processing such as positioning calculation is performed between the tracking processings. Therefore, a CPU (central processing unit) having extremely high-speed processing capability is required, and there is a problem that power consumption increases. Also,
There is also a problem that the operation time is short when the GPS receiving device is driven by a battery.

The present invention was devised in view of the above circumstances, and an object thereof is to provide a GPS receiving apparatus capable of reducing power consumption and extending operating time.

[0008]

A GPS receiver according to claim 1 of the present invention selects a high-speed clock for operating the system at high speed, a low-speed clock for operating the system at low speed, and the high-speed clock and the low-speed clock. Based on the orbit information of the GPS selector, the orbit information table storing the orbit information of the GPS satellites, and the orbit information of the GPS satellites.
If even one of them is at a low elevation angle, the clock selection
All of the multiple satellites using a high speed clock
At high elevations, the clock selector
And a control device for instructing switching to use a high speed clock .

According to a second aspect of the present invention, there is provided a GPS receiver which comprises a high-speed clock for operating the system at high speed, a low-speed clock for operating the system at low speed, and a clock selector for selectively switching between the high-speed clock and the low-speed clock. A positioning result comparison device that compares positioning results that are repeatedly processed with the positioning result comparison device.
The rate of change in the positioning result is larger or smaller than the specified value.
If the rate of change in positioning results is small,
Positioning using a low-speed clock with the clock selector
When the rate of change in the result is large, the clock selector
And a control device for instructing switching of the clock selector so that a high-speed clock is used .

[0010]

According to the GPS receiver of the first aspect, the GPS
The orbit information obtained by receiving the signals from the satellites is stored in the orbit information table, and the positions of all the satellites can be predicted from this orbit information. However, in satellites with a low elevation angle, the error in predicting the position of the satellite becomes large due to the influence of the atmosphere, etc., and accurate prediction becomes difficult. Therefore, the control device knows the position of the GPS satellite based on the orbit information from the orbit information table, and if even one of the plurality of satellites used for positioning has a low elevation angle affected by the atmosphere or the like, it uses the clock selector. If a high-speed clock is selected and satellites are tracked at high speed, conversely, if all the satellites used for positioning are in a high elevation angle that is not easily affected by the atmosphere, select a low-speed clock with the clock selector. The position of is predicted and the tracking processing interval is lengthened. Then, the surplus time is allocated to processing other than tracking processing such as positioning calculation.

According to another aspect of the GPS receiver of the present invention, the controller has a large rate of change in the positioning result from the positioning result comparison device, and at least one of the satellites used for positioning is affected by the atmosphere or the like, resulting in a prediction error. If there is a possibility that it will occur, the high-speed clock is selected by the clock selector to track the satellite at high speed. Conversely, when the rate of change in the positioning result is small, the low-speed clock is selected by the clock selector to predict the satellite position. Then, the tracking processing interval is lengthened. Then, the surplus time is allocated to processing other than tracking processing such as positioning calculation.

[0012]

Embodiments of the GPS receiving apparatus according to the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 shows the GPS of the first embodiment.
It is a block diagram which shows the structure of a receiver. Here, an example in which there are two types of operation clocks will be described. In FIG. 1, 11 is a high-speed clock for operating the system at high speed, and 12 is a low-speed clock for operating the system at low speed. When the high speed clock 11 is used, the power consumption increases, while when the low speed clock 12 is used, the power consumption decreases. Reference numeral 13 is a clock selector for selecting and switching between the high speed clock 11 and the low speed clock 12, and 14
Is a control device that performs tracking processing and positioning calculation, and 15 is each G
It is an orbit information table that can know the orbit and position of the PS satellite.

The orbit information can be obtained by receiving signals from GPS satellites and is stored in the orbit information table 15. Then, the positions of all the satellites can be predicted from the orbit information.

However, in a satellite with a low elevation angle, the error in predicting the position of the satellite increases due to the influence of the atmosphere. Therefore, the conventional GPS receiver requires high-speed tracking processing, requires a CPU having an extremely high-speed processing capability, and increases power consumption and shortens operating time.

In the present embodiment, the control device 14 knows the position of the GPS satellite based on the orbit information from the orbit information table 15 and uses three or more GPSs for positioning.
In the case where even one of the satellites has a low elevation angle affected by the atmosphere and the like, the clock selector 13 is driven by the select signal to capture the operation clock from the high speed clock 11 to perform tracking processing of the satellite at high speed, and vice versa. When all three or more satellites used for positioning have a high elevation angle that is less likely to be affected by the atmosphere, the clock selector 13 is driven by the select signal to capture the operation clock from the low-speed clock 12 The position is predicted and the tracking processing interval is lengthened. Then, the surplus time is allocated to processing other than tracking processing such as positioning calculation. Then, of course, you can afford time. The power consumption can be reduced by slowing down the operation clock, and the operation time can be extended when the GPS receiving device is driven by a battery.

[Second Embodiment] FIG. 2 shows the GPS of the second embodiment.
It is a block diagram which shows the structure of a receiver. In FIG. 2, 21 is a high-speed clock for operating the system at high speed, 22 is a low-speed clock for operating the system at low speed, 23 is a clock selector for selecting and switching between the high-speed clock 21 and the low-speed clock 22, and 24 is a tracking process. The reference numeral 25 denotes a positioning result comparison device that compares positioning results that are repeatedly processed with respect to the orbits and positions of each GPS satellite. The control device 24 is configured to instruct switching of the clock selector 23 based on the information on the positioning result compared by the positioning result comparison device 25.

FIG. 3 is a flow chart showing the flow of processing of the second embodiment. In the present embodiment, the criterion for switching the clock is not how the GPS satellites are arranged, but how much from the previous positioning result.
The GPS satellite has an orbit period of 12 hours and moves at a very low speed when viewed from an observer on the ground. Therefore, generally, the positioning result for each time does not change extremely. If the rate of change is large, it is considered that an error has occurred in the GPS satellite position prediction due to the influence of the atmosphere and the like because the satellite tracking interval is long. In such a situation, the prediction of the position of the GPS satellite becomes inaccurate, so the operation clock is switched at high speed, and the interval of the tracking process is shortened as in the conventional example.

Explaining with reference to FIG. 3, GPS satellites are first captured (S11). And 3 or more GPS
After the satellite is captured, positioning calculation is performed (S12). next,
The current positioning result is compared with the previous positioning result, and it is determined whether the rate of change in the positioning result is larger or smaller than a predetermined value (S13), and it is necessary to switch the operation clock based on the determination. If the rate of change of the positioning result is small, it is operated with a low-speed clock for the prediction process (S15), and if the rate of change of the positioning result is large, it is operated with a high-speed clock for the high-speed tracking process. (S16). After selecting the operation clock, the process returns to the positioning calculation (S12), and the same operation is repeated thereafter.

That is, the control device 24 determines that the rate of change in the positioning result from the positioning result comparison device 25 is small (at this time, all three or more satellites used for positioning are not easily affected by the atmosphere or the like). At a high elevation angle), the clock selector 13 is driven by the select signal to fetch the operation clock from the low-speed clock 22 to predict the position of the GPS satellite and lengthen the tracking processing interval. Then, the surplus time is allocated to processing other than tracking processing such as positioning calculation. Conversely, when the rate of change in the positioning result from the positioning result comparison device 25 is large (3
At least one of the two or more satellites is at a low elevation angle affected by the atmosphere, etc.), and the control device 24 drives the clock selector 13 by the select signal to fetch the operation clock from the high speed clock 21 to make the satellite operate at high speed. Perform tracking processing.

As described above, while the GPS satellite is always accurately tracked by switching the operation clock, the power consumption can be reduced when the low speed clock 22 is used, and the operation time can be reduced when the GPS receiver is driven by the battery. Can be extended.

[0022]

According to the GPS receiver of claim 1 of the present invention, the high-speed clock is set when the satellite used for positioning based on the orbit information from the orbit information table has a low elevation angle affected by the atmosphere. Select and perform satellite tracking processing at high speed, and if the elevation angle is affected by the atmosphere, select a low-speed clock to predict the satellite position and increase the tracking processing interval to give time margin. By lowering the operation clock speed, it is possible to reduce power consumption and extend the operation time when driven by a battery.

According to the GPS receiving apparatus of the second aspect of the present invention, the rate of change of the positioning result from the positioning result comparing apparatus is large, and at least one of the satellites used for positioning is affected by the atmosphere or the like and an error occurs in the prediction. When there is a possibility of occurrence, a high-speed clock is selected to perform satellite tracking processing at high speed, and when the rate of change in positioning results is small, a low-speed clock is selected to predict the satellite position and the tracking processing interval is lengthened. As a result, it is possible to reduce the power consumption by providing a time margin and reducing the operation clock speed, and it is possible to extend the operation time when the battery is driven.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a GPS receiving apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a GPS receiving device according to a second embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation of the GPS receiving apparatus according to the second embodiment.

FIG. 4 is a block diagram showing a configuration of a general GPS receiver of a conventional example.

FIG. 5 is a conceptual diagram showing a control flow of a conventional GPS receiving apparatus.

[Explanation of symbols]

11,21 ... High-speed clock 12, 22 ... Low speed clock 13, 23 ... Clock selector 14, 24 ... Control device 15 ... Orbit information table 25: Positioning result comparison device

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Claims (2)

(57) [Claims] 1. A high-speed clock for operating the system at high speed, a low-speed clock for operating the system at low speed, a clock selector for selecting and switching the high-speed clock and the low-speed clock, and orbit information storing orbit information of GPS satellites. Table and one of the satellites used for positioning based on the orbit information in the orbit information table
But if you have a low elevation,
It uses a faster clock and all of the
If it is on a corner, the clock selector
And a controller for instructing switching to use the GPS receiver. 2. A high-speed clock for operating the system at high speed, a low-speed clock for operating the system at low speed, a clock selector for selecting and switching the high-speed clock and the low-speed clock, and positioning for comparing positioning results repeatedly processed. The result comparison device and the positioning result comparison device
Therefore, the rate of change in the compared positioning results is lower than the predetermined value.
Judge whether it is large or small, and the rate of change in positioning result is small.
When using the low-speed clock, use the clock selector described above.
If the rate of change in positioning results is large, the
And a control device for instructing switching of the clock selector so that a high speed clock is used by the selector.