JP3943870B2 - Navigation system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a navigation system using GPS (Global Positioning System).
[0002]
[Prior art]
This type of navigation system is generally configured to superimpose the map data recorded on a CD-ROM, DVD, etc. and the current position obtained from GPS, etc., and also receives GPS signals received from GPS satellites. There are also known devices that can also display the current time of the current position based on the time difference at the current position with respect to the standard time UTC (Universal Time Coordinated) obtained by performing leap second correction of the time. Conventional navigation systems are sold by setting only the time difference with respect to UTC in a limited area, and for example, for Japan, hardware and maps set in advance for Japan are used. Software is installed. Then, the current time in Japan is calculated and displayed based on the time difference between the UTC obtained by correcting the GPS time received from the GPS satellite and the preset UTC.
[0003]
[Problems to be solved by the invention]
However, in the above conventional navigation system, UTC is converted into the current time of only a preset region, so that even if the user has a navigation system for Japan, for example, the map of the United States can be displayed. However, there was a problem that the UTC or Japan time could not be converted to the current time in the United States. Therefore, it was necessary for manufacturers to produce a navigation system for each destination.
[0004]
In view of the above-described problems of the conventional example, the present invention provides a navigation system that can receive a GPS satellite and convert the obtained UTC to the current time in any region without distinguishing the destination by hardware. The purpose is to provide.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to claim 1 of the present invention, a correction table in which a time correction value for UTC is stored in advance for each region is provided, and the time correction value is searched by judging the region from the map data. The current time is calculated based on the UTC acquired based on the GPS satellite and the time correction value, and if the current location obtained by GPS positioning is not within the map data area, the map disk abnormality is displayed .
With the above configuration, the current time is calculated based on the UTC acquired based on the GPS satellite and the time correction value corresponding to the area of the correction table. Therefore, it is possible to convert the received UTC from the GPS satellite and convert it to the current time in any region without distinguishing the destination by hardware. The correction table may be stored in a map disk storing map data of a predetermined area and area information related to the map data (Claim 2), or may be stored in a storage means different from the map disk. (Claim 3)
[0006]
According to claim 4 of the present invention, the time correction value for UTC is read from the map data, received from the GPS satellite, the current time is calculated based on the obtained UTC and the time correction value, and obtained by GPS positioning. If the current location is not within the map data area, the map medium abnormality is displayed .
With the above configuration, the current time is calculated based on the UTC acquired based on the GPS satellite and the time correction value for the UTC read from the map data. Therefore, it is possible to convert the received UTC from the GPS satellite and convert it to the current time in any region without distinguishing the destination by hardware .
Also, according to claim 5 of the present invention further comprises a storage means for storing the time correction value.
With the above configuration, once the time correction value is stored, it is not necessary to read it once.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
<First Embodiment>
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of a navigation system according to the present invention, FIG. 2 is an explanatory diagram schematically showing the operation of the navigation system of FIG. 1, and FIG. 3 shows the operation of the navigation system of FIG. FIG.
[0008]
A navigation system shown in FIG. 1 includes a position detector 1 that detects a current position, and a map data input device 5 that inputs map data stored in a map disk (not shown) such as a CD-ROM, DVD, or magnetic disk. And an operation switch group 6, a control circuit 7, an external memory 8, a display device 11, an external information input / output device 10, and a real time clock (RTC) 9. The position detector 1 includes a gyroscope 2, a distance sensor 3, and a GPS receiver 4. The GPS receiver 4 performs arithmetic processing on signals received from three or more GPS satellites, and calculates the latitude and longitude of the current position. And the standard time UTC can be obtained based on the received signal.
[0009]
The map disc stores, for example, area information (region data storage area) in which map data of a predetermined region such as a map of Japan and region information (for example, Japan) related to the map data are stored. The control circuit 7 is provided with a time correction table 7a in which a time difference with respect to the standard time UTC is described as a time correction value for each map (area). This time correction table 7a is shown in FIG. FIG. 2 shows, as an example, time correction values and correction equations for US Washington DC, England, Melbourne, and Tokyo. In this way, by storing in advance the time correction value (time difference) with the standard time for each area in the time correction table 7a in the control circuit 7, based on the standard time and the time correction value in the area information related to the map data. The time of the current position can be set in RTC9.
The correction of the current time will be described with reference to FIG.
The control circuit 7 has a system information management unit 100, and this system information management unit 100 confirms the area data storage area of the map disk at the initial startup and acquires the area information. And the time correction value of the area | region of a map disc is determined from the correction table 7a. Then, the radio wave transmitted from the GPS satellite is received, the UTC time is leap second corrected to obtain UTC, and the current time is calculated based on the time correction value already determined for the obtained UTC.
[0010]
The operation in the control circuit 7 will be described more specifically with reference to FIG.
First, when a navigation (hereinafter also referred to as “navigation”) device is activated by turning on power in step S1, map data processing shown in step S2 and subsequent steps and GPS reception processing shown in step S6 and lower steps are executed in parallel. . Since the initial state is the state at the time of shipment, the region is, for example, Japan, the navigation start time (1) is, for example, 2000.11.30, 14:00, and the time valid flag is 0 (= not accurate). To do. The control circuit 7 determines whether or not a map disk is set in the map data input device 5 in step S2. If the map disk is not set (S2: NO), the operator is instructed to insert the map disk (step S3). When the map disk is set (S2: YES), the map disk is accessed and the area information is acquired from the map data and its area data storage area (step S4). Next, a time correction value with UTC is determined and held based on the acquired area information (time correction table 7a, step S5). When the map disk is, for example, US (United States), the time correction value with UTC = 5h is determined.
[0011]
On the other hand, in step S6, reception of GPS signals is started, and GPS positioning (current location acquisition) is started in step S7. Since GPS positioning requires a certain amount of time (depending on the situation, for example, about 5 minutes), GPS positioning does not start immediately after activation. Therefore, until positioning is started, a negative determination is made in step S7 (S7: NO), the time valid flag is reset to 0 (= inaccurate) (step S8), and then the time of RTC 9 is left as the default value (1). (Step S9). Until a positive determination is made in step S7, a normal navigation operation is executed at this time (step S10). Until the GPS positioning starts in this way, a normal navigation operation is executed using the time of the default location (for example, Japan) held before the start-up.
[0012]
When GPS positioning is started in step S7 (S7: YES), UTC obtained by correcting the current location (latitude / longitude) and GPS time with leap seconds is acquired, and the time valid flag is set to 1 (= accurate) (step S11). Next, the current time (2) of the current position is calculated based on the acquired UTC and the time correction value determined and held in step S5 described above, and this is set in the RTC 9 (step S12).
For example, if UTC is November 30, 2000 14:05 and the map disc is US correction value = 5h, the current time {circle around (2)} is November 30, 2000 AM 9:05.
[0013]
Next, it is determined whether or not the current location (latitude / longitude) obtained by GPS positioning is within the map data region (step S13). If yes, the current location is updated and a map is drawn (step S14). A normal navigation operation is executed at this time (step S10). On the other hand, in the case of no, a map disk abnormality is displayed on the assumption that a map disk different from the current position has been inserted (step S15).
[0014]
In the first embodiment, when the map data is read, the area information of the map is read, and the time correction value for UTC acquired based on the area information is detected from the correction table. If the value itself is directly associated with the map data and recorded on the map disk, there is no need to search the correction table based on the area information.
[0015]
If the time correction value for the UTC obtained in the first or second embodiment is stored in a backup memory (nonvolatile memory) or the like, the time for the UTC every time the vehicle IG (ignition) is turned on. There is no need to search for and read out correction values. Also, if large map data with multiple time zones is recorded on the map disc as in the United States, the area information and correction values for each time zone are stored in advance on the map disc, and the current location An accurate current time can be calculated by reading out information and correction values. Further, the area information recorded on the map disk may be 24 types if the time zone code is used instead of the country code or the area code such as Japan.
[0016]
As described above, according to the present embodiment, a correction table in which a time correction value with UTC is stored in advance for each region is provided, a region is determined from map data, a time correction value is searched, and a GPS satellite is used. Since the current time is calculated based on the obtained UTC and the time correction value for UTC, the standard time obtained from the GPS satellite can be obtained from the current location in any area without distinguishing the destination by hardware. Can be converted to time.
Also, the time correction value for UTC is retrieved from the map data, and the current time is calculated based on the UTC obtained from the GPS satellite and the time correction value, so that the destination is not distinguished by hardware. The standard time obtained from the GPS satellite can be converted into the current time in any region.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a preferred embodiment of a navigation system according to the present invention.
FIG. 2 is an explanatory diagram showing an example of a time correction table.
FIG. 3 is an explanatory diagram schematically showing the operation of the navigation system of FIG. 1;
4 is a flowchart specifically showing the operation of the navigation system of FIG. 1. FIG.
[Explanation of symbols]
4 GPS receiver 5 Map data input device 7 Control circuit 7a Time correction table 9 Real time clock (RTC)

Claims (5)

In a navigation system having a GPS receiver for receiving radio waves transmitted from a GPS satellite and UTC acquisition means for acquiring UTC based on the received radio waves,
A map disk storing map data of a predetermined area and area information related to the map data;
Reading means for reading out the area information from the map disk ;
Search means for searching for a time correction value for the UTC acquired by the UTC acquisition means based on the area information read by the reading means from a correction table in which the time correction value for the UTC is stored in advance for each area;
Means for calculating the current time based on the UTC acquired by the UTC acquisition means and the time correction value searched by the search means ;
With
A navigation system characterized in that it is determined whether or not the current location obtained by GPS positioning is within the area of the map data, and if it is determined that the current position is not within the area, the map disk abnormality is displayed . The navigation system according to claim 1, wherein the correction table is stored in the map disk . The navigation system according to claim 1, wherein the correction table is stored in a storage unit different from the map disk . In a navigation system having a GPS receiver for receiving radio waves transmitted from a GPS satellite, means for reading map data and displaying a map on a screen, and UTC acquisition means for acquiring UTC based on the received radio waves,
A storage medium for storing the area information related to the map data and the map data;
Means for obtaining a time correction value for the UTC based on the area information ;
Means for calculating a current time based on the UTC acquired by the UTC acquisition means and a time correction value for the UTC ;
With
A navigation system characterized by determining whether or not the current location obtained by GPS positioning is within the area of the map data, and displaying the map medium abnormality when it is determined that the current position is not within the area . The navigation system according to any one of claims 1 to 4 , further comprising storage means for storing the time correction value.

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