JP3260038B2 - GPS receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a GPS orbiting the earth.
The present invention relates to a GPS receiving device that obtains the position and moving speed of a GPS receiving device from a (global positioning system) satellite.

[0002]

2. Description of the Related Art GPS simultaneously receives radio waves from a plurality of GPS satellites and obtains navigation messages (orbit information, time information, etc.) from the GPS satellites, thereby calculating the position and moving speed of the GPS receiver. System.

Assuming that the clocks of the GPS satellite and the GPS receiver are correctly set, the difference between the time at which the GPS satellite transmits radio waves and the time at which the GPS receiver receives the radio waves is multiplied by the speed of light to obtain the GPS satellite. The distance from the GPS receiver can be obtained.

Further, the position of a GPS satellite can be known from the orbit information of the navigation message. In principle, to calculate the position of the GPS receiver in three dimensions, three or more GPS
Regarding satellites, the positions of GPS satellites, each GPS satellite and G
What is necessary is just to know the distance of the PS receiver. In fact, GP
Since there is an error between the S satellite and the clock of the GPS receiver, simultaneous equations relating to four or more GPS satellites having the clock error as an unknown must be established.

Therefore, in order to calculate the three-dimensional position of the GPS receiver, it is necessary to receive radio waves from four or more GPS satellites. At this time, when the altitude information of the GPS receiver is obtained and the two-dimensional position is calculated, radio waves of three or more GPS satellites may be received.

Hereinafter, an example of the above-described conventional GPS receiver will be described with reference to the drawings.

FIG. 4 is a block diagram showing a configuration of a conventional GPS receiver. In FIG. 4, 1 is a GPS antenna for receiving radio waves from GPS satellites, 2 is a satellite signal receiving unit having a plurality of channels, 3 is a positioning calculation unit, 4 is a storage unit, and 7 is a tracking satellite selection unit.

[0008] The operation of the GPS receiving apparatus configured as described above will be described below.

The navigation message of each GPS satellite is obtained from the radio wave of the GPS satellite obtained from the GPS antenna 1 by using the satellite signal receiving means 2. This navigation message includes time information for knowing the transmission time of the GPS satellite signal,
Orbit information of the satellite for knowing the position of the GPS satellite is included. The satellite signal receiving means 2 has a plurality of channels, and can perform detection processing in parallel on separate GPS satellites for each channel.

Using the time information and the orbit information, the position of the GPS receiver is calculated by the positioning calculation means 3.
In order to be able to calculate the position of the GPS receiver, it is necessary to receive radio waves from at least three GPS satellites as described above.

The tracking satellite selecting means 7 selects the GPS satellite to be tracked by the satellite signal receiving means 2. Since the GPS satellites that can receive radio waves with the GPS receiver change with time and with the position of the GPS receiver, it is necessary to update the tracking satellite each time. The storage unit 4 stores a part of the positioning calculation results necessary for this.

The tracking satellite selecting means 7 selects tracking satellites by the number of channels of the satellite signal receiving means 2. The tracking satellite selecting means 7 calculates the “viewing of the GPS satellite from the GPS receiving apparatus” which is calculated based on both the position of the GPS satellite obtained from the satellite orbit information of the navigation message and the position of the GPS receiving apparatus obtained by the positioning calculating means 3. GPs in ascending order of the number of channels
S satellite is selected.

[0013]

However, in the above-described configuration, a vehicle equipped with a GPS receiver travels in an area where radio waves are shielded, such as a tunnel or a valley of a building, so that the GPS tracking is performed. When the radio wave from the satellite is cut off, a GPS satellite with a large “elevation angle when viewing the satellite from the GPS receiver” selected immediately before the cut off of the radio wave is searched. For this reason, even though there is a GPS satellite that can actually receive radio waves, this GPS satellite may not be selected as a tracking satellite. In other words, there is a problem that a GPS satellite having high receivability is not necessarily selected as a tracking satellite.

In view of the above problems, the present invention is based on the fact that a vehicle equipped with a GPS receiver travels in an area where radio waves are shielded such as a tunnel or a valley of a building. When you can no longer calculate,
Select GPS satellites with high reception potential as tracking satellites,
It is an object of the present invention to provide a GPS receiving apparatus capable of shortening the time until the positioning calculation is started again.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve the object, the present invention provides a GPS which is obtained immediately before a radio wave from a GPS satellite is cut off and positioning calculation becomes impossible.
New means for estimating the traveling direction of the GPS receiver from the traveling direction of the receiving device and the integrated value of the output of the angular velocity sensor thereafter is provided, and the GPS satellite having a high receivability is tracked based on the estimated traveling direction. As priority.

[0016]

According to the present invention, when the radio wave from the tracked GPS satellite is cut off and the positioning calculation becomes impossible, based on the traveling direction estimated by the receiving device traveling direction estimating means, By selecting the tracking satellite selecting means so as to preferentially search for a GPS satellite having a high possibility of receiving as a tracking satellite, the time for receiving a radio wave from the GPS satellite can be shortened again. Thereby, the frequency with which the positioning calculation can be performed can be improved.

[0017]

FIG. 1 is a block diagram showing the configuration of a GPS receiver according to an embodiment of the present invention. In FIG. 1, 1
Is a GPS antenna, 2 is a satellite signal receiving unit having a plurality of channels, 3 is a positioning calculation unit, and 4 is a storage unit for storing a positioning result. In the present invention, in addition to the conventional configuration, 5 receiving device traveling direction estimating means is provided, and 6 is tracking satellite selecting means for determining a GPS satellite to be tracked using the traveling direction of the GPS receiving device.

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

The receiving device traveling direction estimating means 5 can estimate the traveling direction of the GPS receiving device even when the radio wave from the tracked GPS satellite is cut off and the positioning calculation becomes impossible. You can do it. Here, in order to estimate the traveling direction, G just before positioning calculation becomes impossible is performed.
The traveling direction of the PS receiver and the integral value of the output of the angular velocity sensor after that are required. The former is obtained from the storage means 4, and the latter is obtained from the outside.

Next, when the radio wave from the GPS satellite that was being tracked is cut off and positioning calculation becomes impossible, the tracking satellite selecting means 6 selects the tracking direction estimating means 5 for the receiving device.
This is a means for preferentially selecting a GPS satellite having a high reception possibility based on the traveling direction estimated by (1). The satellite signal receiving means 2 searches for the GPS satellite selected by the tracking satellite selecting means 6.

Next, the receiver traveling direction estimating means 5 will be described. The traveling direction θ ₀ of the GPS receiver immediately before the radio wave from the tracked GPS satellite is cut off and the positioning calculation becomes impossible is acquired from the storage unit 4. This θ ₀ is GP
This is an initial value of the traveling direction of the S receiving device. Here, the traveling direction is represented by an azimuth θ in which north is 0 degree and a direction from north to east is plus. Further, an angular velocity sensor is used as an external sensor to acquire the angular velocity ω _τ of the GPS receiver even while positioning calculation is impossible. At this time, the estimated value theta _t of the receiver traveling direction at time t is as (Equation 1). The receiver traveling direction estimating means 5 calculates this θ _t at time t
Is output as an estimated value of the traveling direction of the GPS receiver at

[0022]

(Equation 1)

Next, a first example of the tracking satellite selecting means 6 will be described. When the radio wave from the GPS satellite that was being tracked is cut off and positioning calculation becomes impossible, based on the estimated traveling direction of the GPS receiver,
The PS satellite is preferentially selected.

For example, as shown in FIG. 2, the azimuth θ of the GPS satellite obtained based on the estimated traveling direction and the G
An upper limit θ _max of θ and an upper limit φ _max of φ are provided to obtain an elevation angle φ when the GPS satellite is viewed from the PS receiver and preferentially select a GPS satellite ahead in the traveling direction.
Among the GPS satellites that satisfy ≦ θ _max and φ ≦ φ _max , the GPS satellites with the higher elevation angle φ are selected in order. With respect to the number of channels of the satellite signal receiving means 2, it is determined how many GPS satellites selected under the above conditions are to be selected as tracking satellites. In the same manner as
The GPS satellites having the larger elevation angles when viewing the PS satellites are sequentially selected. To calculate the elevation angle, the position of the GPS receiver must be known. As the position of the GPS receiver, the position of the GPS receiver immediately before the positioning calculation becomes impossible is obtained from the storage unit 4 and used. .

In this example, it is assumed that a radio wave is cut off by a tunnel or the like. By using the tracking satellite selecting means 6, a GPS satellite ahead in the traveling direction having a high possibility of receiving is preferentially searched.

Next, a second example of the tracking satellite selecting means 6 will be described. When the radio wave from the tracked GPS satellite is cut off and positioning calculation becomes impossible, based on the estimated traveling direction of the GPS receiver, as shown in FIG. A straight line including a traveling direction vector starting from the GPS receiver,
With respect to a plane including both straight lines connecting the zenith viewed from the S receiving device, a GPS satellite having a small angle す formed by the straight line connecting the GPS receiving device and each GPS satellite position is preferentially selected.

With respect to the number of channels of the satellite signal receiving means 2, it is determined how many GPS satellites selected under the above conditions are to be selected as tracking satellites. Similar to the satellite selecting means, the GPS satellites are selected in order from the GPS satellite having the largest elevation angle when the satellite is viewed from the GPS receiver. In addition, as the position of the GPS receiving apparatus during which the positioning calculation is not possible, the radio wave from the GPS satellite is cut off and the GP immediately before the positioning calculation becomes impossible.
The position of the S receiving device is obtained from the storage unit 4 and used.

In this example, it is assumed that radio waves are blocked by buildings and trees on both the left and right sides in the traveling direction.
By using GPS satellites, GPS satellites that are less susceptible to buildings and trees and have high receivability are preferentially selected.

As described above, even when the radio wave from the tracked GPS satellite is cut off and positioning calculation becomes impossible, the traveling direction of the GPS receiving apparatus is estimated by the receiving apparatus traveling direction estimating means 5. By using the estimated traveling direction, the tracking satellite selecting means 6 preferentially searches for a GPS satellite having a high reception possibility,
Again, the time for receiving the radio wave from the GPS satellite can be shortened.

[0030]

As described above, the GPS receiving apparatus according to the present invention is provided with the receiving apparatus traveling direction estimating means for estimating the traveling direction of the GPS receiving apparatus even when positioning calculation is impossible. , GP that is highly likely to be received using the estimated traveling direction
The S satellite is preferentially selected, so that the time for receiving the radio wave from the GPS satellite can be shortened again, and the frequency of the positioning calculation can be improved.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of a tracking satellite selecting means of the first example of FIG. 1;

FIG. 3 is an explanatory diagram of a tracking satellite selecting means of the second example of FIG. 1;

FIG. 4 is a block diagram illustrating a configuration of a conventional GPS receiver.

[Explanation of symbols]

1 ... GPS antenna, 2 ... Satellite signal receiving means, 3 ...
Positioning calculation means 4, storage means 5, receiving apparatus traveling direction estimation means 6, 7, tracking satellite selection means.

Claims (3)

(57) [Claims] 1. A satellite signal receiving means having a plurality of channels for receiving a GPS satellite signal from a GPS antenna,
Seeking the propagation time of the satellite signals calculated by said satellite signal receiving means, and a received data in the propagation time and the satellite signal receiving means, two-dimensional or three-dimensional position of the receiving device
And a positioning calculation means for calculating the traveling direction, and memory means for storing the positioning calculation results of the positioning calculation means, said measuring
Even if positioning calculation by means of position calculation is temporarily disabled
A receiving device traveling direction estimating means traveling direction can estimate of the receiving apparatus, measuring the wave is cut off from the GPS satellites
Tracking satellite selecting means for preferentially selecting a GPS satellite in a traveling direction with a high receivability using the traveling direction estimated by the receiving device traveling direction estimating means when positioning calculation cannot be performed by the position calculating means. G, characterized by
PS receiver. 2. The apparatus according to claim 2, wherein said receiving device traveling direction estimating means is a satellite.
The propagation time obtained by the signal receiving means and the satellite signal receiver
It is calculated immediately before can not positioning calculation by the data received in step with the positioning calculating means, the traveling direction of the storage of <br/> the said receiving device to said storage means as an initial value, the subsequent angular rate sensor output By adding the integral value to the initial value
2. The GPS receiving device according to claim 1, wherein the current traveling direction of the receiving device is estimated. 3. The tracking satellite selecting means, when a radio wave from a GPS satellite is cut off and positioning calculation cannot be performed,
Receiving device position and traveling direction vector starting from the receiving device
Straight line connecting the straight line containing
Receiver and each GPS satellite position relative to a plane containing both lines
2. The GPS receiving apparatus according to claim 1, wherein the one having a small angle with a straight line connecting the positions is preferentially selected.