JPH0827340B2 - GPS navigation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a GPS navigation device for various mobile objects, and particularly to a GPS receiving means among a plurality of artificial satellites constituting GPS. Which can be used to calculate the current position of the mobile unit received by the mobile unit, that is, depending on the number of available units, the mobile unit has a different way of coping with, The present invention relates to a GPS navigation device in which the display method on the display device is changed according to the number of available artificial satellites.

[Conventional technology]

A GPS positioning device is useful for transmitting radio waves from various artificial satellites to various moving objects such as ships, aircraft, automobiles, etc., and confirming and determining the current position, moving speed, etc. Has been noticed. here,
A GPS positioning device is a global positioning system or GPS ( G roba
It receives radio waves from a plurality of artificial satellites belonging to the l P ositioning S ystem), those that are to be able to know the current position of the moving body.

As is conventionally known, a positioning operation performed using such a GPS positioning device is usually performed by receiving radio waves from three or four artificial satellites. Then, the radio waves from a plurality of artificial satellites are simultaneously received on the mobile body side, the current position of the mobile body is calculated based on the information from the plurality of artificial satellites, and the current position of the mobile body is appropriately displayed. It is supposed to be displayed on the device. At this time, the necessary map information is displayed on the display device, being superimposed on the information about the current position.

FIG. 3 is a block diagram showing a conventional GPS navigation device. In FIG. 3, (1) is an antenna for receiving satellite radio waves, and the output side of this antenna (1) is a GP.
It is connected to the GPS receiver (2) as S receiving means.
The pseudo range data obtained by the GPS receiving section (2) is introduced into the position calculating section (3) as a position calculating means. In this position calculation unit (3), accurate latitude, longitude and altitude are calculated based on the pseudo distance data, and as a result, the accurate current position of the moving body is detected. The data on the current position obtained in this manner is stored in the data storage unit (5) via the data processing unit (4). The display unit (6)
Includes, for example, a display device such as a CRT that displays a related map and the current position of a mobile object in an overlapping manner. The GPS navigation device having such a configuration is activated by operating an appropriate function key such as a start key of a keyboard (not shown). After entering the operating state in this way, radio waves from a plurality of artificial satellites are received by the antenna (1).
The GPS receiving unit (2) measures the pseudo distance to each artificial satellite based on the radio waves thus received, and supplies the pseudo distance data corresponding thereto to the position calculating unit (3).
In the position calculation unit (3), the latitude, longitude and altitude of the current position of the moving body are calculated based on the pseudo distance data, and the calculation result is stored in the data storage unit (5).
To memorize. In the data processing unit (4),
For example, necessary map information is extracted from a map storage unit (not shown) serving as a data storage unit, and various types of information necessary for displaying the map information on the display unit (6) are superimposed on the current position of the moving body. Data processing is performed.
Thus, the position information of the moving object such as the current position, the moving speed, the traveling direction and the like from the data storage unit (5) and the map information for the moving object corresponding to the moving route are displayed on the display unit (6) ) Is superimposed and displayed on the screen.

By the way, when such an operation is performed, the usable number that can be used by this artificial satellite is determined by the number determining means. In the GPS receiving device, if the signal from the artificial satellite can be demodulated by the carrier channel device, the information regarding the positioning by GPS can be obtained from the artificial satellite. The GPS receiving device is provided with a plurality of carrier channel devices, and the number of artificial satellites that can be used can be easily determined by monitoring the output of the carrier channel device. Depending on the current position of the mobile body, the number of usable artificial satellites may be three or four.

Here, the degree of freedom of the coordinates of the position of the moving body is 3 in x, y, and z.
It is a dimension. The distance from the artificial satellite to the moving body is determined by the arrival time of the signal from the artificial satellite. Therefore, a timepiece device is provided on each of the artificial satellite side and the mobile body side to determine the arrival time of the signal. However, in general, a difference in accuracy between the clock devices on the mobile body side and the artificial satellite side causes an error in measuring the arrival time of the signal. Therefore, for positioning, since there are a total of four unknowns, which are three degrees of freedom of position and time, a minimum of four usable artificial satellites is required. That is, when the number of usable artificial satellites is 4, the position of the moving body can be obtained with high accuracy.
On the other hand, when the mobile body receives radio waves from three artificial satellites, it is possible to perform two-dimensional (latitude, longitude) positioning, but a large measurement error may occur due to the following reasons. . That is, when obtaining the latitude and longitude in such a two-dimensional positioning, appropriate altitude data corresponding to them, for example, the altitude data obtained when there are four usable artificial satellites are used. Normally, when a moving body such as an automobile moves along a certain predetermined moving route, the altitude data is set to a certain fixed value. However, in reality, the moving route of the moving body such as the automobile may pass through a place having a considerable altitude difference, such as a mountain or a valley,
From this, in the preset fixed altitude data as described above, a considerable difference occurs from the actual altitude, and as a result, the latitude and longitude corresponding to the fixed altitude data. A significant error may occur in the measurement position due to.

As is clear from the above description, although there is a considerable difference in the accuracy of the obtained measurement position when the number of artificial satellites that can be used is three and when the number of artificial satellites that can be used is four or more, the mobile unit is displayed on the display unit. It is the current situation that no particular difference is given when displaying the current position of.

[Problems to be solved by the invention]

The conventional GPS navigation device is configured and operates as described above, and when there is a change in the number of usable satellites among the plurality of artificial satellites that make up the GPS, the corresponding GPS navigation device can be operated separately. However, the operator of the moving body cannot immediately confirm how accurately the current position of the user is displayed. was there.

The present invention has been made to solve the above problems, and the accuracy of the current position can be instantly recognized easily depending on the number of artificial satellites that can be used among the artificial satellites that form the GPS. The purpose is to obtain the GPS navigation device.

[Means for solving problems]

A GPS navigation device according to the present invention includes a data storage unit for storing map information, a GPS receiving unit for receiving radio waves from a plurality of artificial satellites belonging to GPS, and a mobile unit based on an output signal from the GPS receiving unit. Current position calculation means for calculating the current position information, a number determination means for determining the number of artificial satellites that can be used by the current position calculation means based on the output signal from the GPS reception means, and based on the map information A map is displayed, the current position is displayed at the position based on the current position information on the map, and the method of displaying the displayed current position is set to the number of usable artificial satellites determined by the number determination means. It is provided with a display means which is different depending on the situation. Further, the display means distinguishes whether the number of usable artificial satellites determined by the number determination means is three or four by making the display color of the current position different.

[Action]

In the present invention, the number of artificial satellites that can be used is determined, and the method of displaying the current position of the mobile unit on the display unit is made different according to the determination result.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a GPS navigation device according to one embodiment of the present invention. In FIG. 1, (5) is a data storage unit as a data storage unit for storing map information, and the one provided in the data processing unit (40) determines the number of usable artificial satellites. The number determination unit (41) serves as a number determination unit for Incidentally, in FIG. 1, (1), (2), and (3) show the same or equivalent parts to those in FIG. 3 described above. Further, FIG. 2 is a flow chart for explaining the operation of the above embodiment.

Next, the operation of the above embodiment will be described with reference to FIGS. 1 and 2. First, as described above, the current position as the position information of the moving body is obtained by changing the calculation method according to the usable number of usable artificial satellites. Now, for example, by pressing a predetermined function key on a keyboard (not shown), the device enters the activated state (S0), and radio waves from a plurality of satellites constituting GPS are received (S1). . Here, the number of artificial satellites that can receive radio waves and can be used is determined (S2). This determination operation is performed by the number determination unit (41) provided in the data processing unit (40).
Is done by. If it is determined that the number of usable artificial satellites is three, the current position of the moving body is displayed in green on the display unit (6) as a display means based on the determination result (S3). . On the other hand, when it is determined that the number of usable artificial satellites is four, the current position of the moving body is displayed in red based on the determination result (S4). That is, the display color of the current position of the mobile changes according to the change in accuracy of the current position of the mobile corresponding to the number of artificial satellites that can receive radio waves.
Then, the operation required for changing the display on the display unit (6) is completed (S5). In addition, the map information is displayed on the display unit (6) so as to be superimposed on the current position.

Note that the number of available satellites that can be received is
The number determination unit (41) can easily determine based on the number of types of radio waves received by the reception unit (2).

Further, in the above embodiment, the display color is changed to indicate that the number of usable artificial satellites is changed, but the present invention is not limited to this. Can be distinguished by displaying flicker and displaying the other without flicker.

〔The invention's effect〕

As described above, the GPS navigation device according to the present invention calculates the current position information of the moving body based on the output signal from the GPS receiving means according to the usable number of artificial satellites that can be used for calculating the current position. , The current position information is displayed by superimposing it on the map by changing the way of displaying the current position information according to the number of usable artificial satellites, so that the accuracy of the current position can be visually and easily confirmed instantly. Play.

[Brief description of drawings]

FIG. 1 is a block diagram showing a GPS navigation device according to an embodiment of the present invention, FIG. 2 is a flow chart for explaining the operation of the above embodiment, and FIG. 3 is a conventional GPS navigation device. It is a block diagram showing. (1) is an antenna, (2) is a GPS receiving section, (3) is a position calculation section, (4) and (40) are data processing sections, (41) is a number determination section, (5) is a data storage section, (6) is the display, (6
1) is a manual switch (display switching means). In the drawings, the same reference numerals indicate the same or corresponding parts.

Front page continued (72) Inventor Harumasa Hojo 5-1-1 Shimorenjaku, Mitaka City, Tokyo Japan Radio Co., Ltd. Mitaka Manufacturing (72) Inventor Koji Yamada 5-1-1 Shimorenjaku, Mitaka City, Tokyo Japan Radio Co., Ltd. Company Mitaka Works (72) Inventor Seiichiro Hirata 2-33 Miwa, Mita City, Hyogo Prefecture Mitsubishi Electric Corporation Mita Works (56) Reference JP 61-137086 (JP, A) JP 62 -882 (JP, A) JP-A-56-137171 (JP, A) JP-A-54-136855 (JP, A)

Claims (2)

[Claims] 1. A GPS receiving means for receiving radio waves from a plurality of artificial satellites belonging to GPS, a current position calculating means for calculating current position information of a moving body based on an output signal from the GPS receiving means, A number determination unit that determines the number of artificial satellites that can be used by the current position calculation unit based on the output signal from the GPS reception unit, and a map based on the map information is displayed, and the current position information on the map is displayed. A GPS navigation device comprising: a display unit that displays the current position at a position based on the display unit and that displays the displayed current position differently according to the number of usable artificial satellites determined by the number determination unit. 2. The display means distinguishes whether the number of usable artificial satellites determined by the number determination means is 3 or 4 by changing the display color of the current position. The GPS navigation device according to claim 1, which is characterized in that.