JP2001255156A - Navigation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a navigation apparatus, in which the number of times of changes in a receiving frequency is reduced by selecting a broadcasting station which has a high possibility of staying in a receivable region and which increases the possibility of giving optimum information to a user. SOLUTION: The navigation apparatus is provided with a GPS positioning means 24, which positions a present position. The apparatus is provided with a RAM 23, in which area information indicating the receivable region of radio waves transmitted from a transmitting station is stored. The apparatus is provided with a control circuit 21, which detects the movement direction of the apparatus, when a plurality of transmitting stations including the present position inside the region exits, which supposes that the apparatus is moved on a line extended in the the movement direction and which selects one or more transmitting stations in the order, in which the movement forecasting distance up to a part outside the region becomes long.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a VICS (Vehicle Information and Communic
The present invention relates to a navigation device that receives various types of information, such as traffic congestion information of a communication system and multiplex information of FM teletext broadcasting.

[0002]

2. Description of the Related Art On April 23, 1996, a VICS service for transmitting traffic congestion information to a navigation device was started. This service information is performed by three communication means of FM multiplex broadcasting, a radio wave beacon, and an optical beacon.

[0003] As of December 21, 1999, there are 15 FM multiplex broadcasting stations, each transmitting different information. Since there are a plurality of FM multiplex broadcasting stations, the navigation device selects a broadcasting station to receive as the vehicle moves. The choice is
This is performed by comparing the reception level with the electric field strength. Since it takes time to search to detect the electric field strengths of all FM multiplex broadcasting stations, first, FM multiplex broadcasting stations that can be currently received without searching based on the FM multiplex broadcasting station area information stored in advance. Is extracted.
Then, only the extracted FM multiplex broadcasting station is searched to set the frequency of the FM multiplex broadcasting station having the highest electric field strength (see Japanese Patent Application Laid-Open No. 9-270720).

Further, as a method of reducing the number of searches, there is also a method of checking whether or not the extracted FM multiplex broadcasting stations can be received in ascending order, and setting the frequency to the frequency of the FM multiplex broadcasting station determined to be receivable first. Conceivable.

[0005]

However, as described above, the method of selecting a transmitting station based on the reception level and the distance to the transmitting station has no relation to the time remaining in the receivable area. For this reason, when a transmitting station that stays in the receivable area for a short time is selected, the number of searches increases. It is not preferable to increase the number of searches because information cannot be received during the search. Also, PL
Power consumption increases by driving the L circuit.

In particular, when a transmitting station transmits information different from other transmitting stations, such as VICS, if a transmitting station that stays within a receivable area for a short time is selected, information that is not optimal for the user is obtained. Likely to give.

[0007]

SUMMARY OF THE INVENTION In view of the above, a navigation device according to the present invention stores positioning means for positioning a current position and area information indicating a receivable area of a radio wave transmitted from a transmitting station. When there are a plurality of transmitting stations in which the current position is within the area, the moving direction of the apparatus is detected, and it is assumed that the apparatus moves on a line extending in the moving direction. Selecting means for selecting one or more transmitting stations in order of increasing distance.

[0008] Further, positioning means for positioning the current position, storage means for storing area information indicating a receivable area of a radio wave transmitted from the transmitting station and a planned movement route of the apparatus, and transmission for setting the current position within the area. And selecting means for selecting one or more transmitting stations in order of increasing distance of the remaining planned route from the current position within the area when there are a plurality of stations.

[0009]

Embodiments of the present invention will be described with reference to the drawings. The navigation apparatus according to the present embodiment receives FM multiplex broadcasting and displays VICS information.

[0010] VICS information is transmitted by three communication means of FM multiplex broadcasting, radio wave beacon and optical beacon. F
M multiplex broadcasting is broadcast from NHK (Japan Broadcasting Corporation) facilities rented by the VISC Center, radio beacons are installed on expressways led by the Ministry of Construction, and optical beacons are general led by the National Police Agency other than expressways. Installed on the road. An FM receiver is required to display VICS information in FM multiplex broadcasting, a radio beacon receiver is required to display VICS information in a radio beacon, and an optical beacon is required to display VICS information in an optical beacon. A receiver is required. In this embodiment, VICS information is displayed by FM multiplex broadcasting, and has an FM receiver.

FIG. 1 is a block diagram showing a configuration of a main part of the embodiment. This device is an FM receiver (FM tuner)
(1) and a current position indicator (2).

In the FM receiver (1), the FM front end (11) amplifies a signal received from the antenna (12) to a high-frequency signal, and converts the high-frequency signal and an oscillation signal from the PLL circuit (13). It mixes and outputs an intermediate frequency signal. The FM-IF detector (14) performs FM on the intermediate frequency signal output from the FM front end (11).
Perform detection.

(15) is a multiplex signal detection circuit, which includes a multiplexing filter (not shown) and a data demodulation circuit (not shown).
Consists of The multiplexing filter is an FM-IF detector (1
The voice signal and the noise component are removed from the output signal of 4), and the multiplexed LMSK (Level Controlled Minimum Shift)
t Keying) Extract the signal. LMSK is a modulation method for controlling the size of a multiplex signal according to the size of a stereo audio signal. The data demodulation circuit demodulates the LMSK signal into a displayable data signal and sends it to the control circuit (16) of the FM receiver (1). The control circuit (16) of the FM receiver (1) instructs the frequency to be set in the PLL circuit (13).

In the current position indicator (2), (21)
Is a control circuit, which performs display based on a program written in the ROM (22). (23) is a RAM, which is information necessary for the operation of the control circuit (21), for example,
The area information of the FM multiplex broadcasting station is stored. (24) is G
PS (Global Positioning System) positioning means, which receives radio waves from GPS satellites, measures the current position, and transmits the measured data to the control circuit (2) of the current position display (2).
Output to 1). (25) is a map reproducing means, which reads map information from the DVD on which the map information is written and outputs it to the control circuit (21). (26) is a liquid crystal display unit which displays a map, a current position, and VICS information under the control of the control circuit (21). An input unit (27) performs various inputs related to the current position display and VICS.

The operation of the embodiment will be described. FIG. 2 is a flowchart showing the main operation of the control circuit (21) of the current position display (2).

Area information is previously stored in the RAM (23). As shown in FIG. 3, the area information includes the frequency, position, and output of each FM multiplex broadcasting station.

In FIG. 2, the control circuit (21) of the current position indicator (2) detects whether or not it is necessary to switch the current reception frequency to the reception frequency of another FM multiplex broadcasting station by detecting a multiplex signal. The determination is made based on whether the multiplex signal has been detected by the circuit (15) (S1). FIG. 4 shows that the reception frequency is F1 (N
This is an example showing a state in which the multiplex signal of the FM multiplex broadcast station of NAME1 cannot be received due to the movement of the device when the multiplex signal is set to AME1, FM multiplex broadcast station at position P1). P
1 to P4 indicate the positions of FM multiplex broadcasting stations. R1 to R4 are virtual radii proportional to the output of the FM multiplex broadcasting station, and P1
Circles with radii R1 to R4 around P4 to P4 are assumed to be receivable virtual areas of the respective FM multiplex broadcasting stations. At this time,
The current position of the vehicle is within a virtual area of the area E2 and the area E3.

When the reception is disabled in FIG. 4, the control circuit (21) of the current position indicator (2) determines that it is necessary to switch the FM multiplex broadcasting station to another FM multiplex broadcasting station (S1). Y). First, the data of the current position and the traveling direction are represented by R
It is stored in the AM (23) (S2). The traveling direction is calculated based on the temporal change of the current position. The control circuit (21) of the current position display (2) extracts the FM multiplex broadcasting station whose current position is within the area as a setting candidate based on the area information stored in the RAM (23) (S3).

Next, assuming that the apparatus continues to travel in the direction of the state where reception was disabled for the candidate FM multiplex broadcasting station, the apparatus moves until it leaves the receivable area (virtual area). The distance to perform is calculated (S4). This calculation can be easily obtained by calculating the XY coordinates. From the simultaneous equation of the quadratic expression of the circle in the virtual area and the linear expression of the straight line extending in the moving direction, two intersections of the circle and the straight line are calculated, and the distance between the intersection on the traveling side and the current position is determined. The distance that the device moves until it moves. In the case of FIG. 4, the coordinates of the current position are A, and the coordinates of the intersections of the circle of the virtual area E2 and the circle of the virtual area E3 intersecting with the line extending in the traveling direction from the coordinate A are B2 and B3. The length (L2) of the line segment AB2 is the separation distance of the virtual area E2, and the length (L2) of the line segment AB3.
3) is the departure distance of the virtual area E3.

Then, the candidate FM multiplex broadcasting stations are arranged in descending order of the separation distance (S5). In FIG. 4, the virtual area E2
Is ranked 1 and the virtual area E3 is ranked 2.

In this order, the reception frequency is changed to check whether or not reception is possible, and the first FM multiplex broadcasting station determined to be receivable is set as a reception station (S6). FM first checked
If the multiplex broadcasting station can receive, the number of times of changing the reception frequency (the number of searches) is one, and the FM multiplex broadcasting station is shifted in a short time.

As described above, it is assumed that the apparatus proceeds in the direction at the time of reception failure, and a station is selected based on the distance the apparatus moves until it leaves the receivable area (virtual area). Assuming that the device moves at a constant speed, it can be said that the present invention selects a station based on the time remaining in the coverage area.

According to the present invention, there is a high possibility that the station will remain in the receivable area of the selected station for a long time, and the number of times of changing the reception frequency is reduced. When the number of times the reception frequency is changed is reduced, power is saved, and the unreceivable time during the search is shortened.

In particular, when a transmitting station transmits information different from other transmitting stations, such as VICS, it is highly likely that the transmitting station will stay in the receivable area of the selected transmitting station for a long time. Likely to give.

When the travel route of the apparatus is predicted due to travel at a destination or the like, the travel distance until the apparatus leaves the receivable area is determined based on the assumption that the apparatus moves.
In this case, a comparison closer to reality can be performed than in the above-described embodiment. For example, in step S4 of FIG. 2, the control circuit (21) of the current position indicator (2) sets the coordinates of the current position to A when the road as shown in FIG. The intersection coordinates of the circle of the virtual area E2 and the circle of the virtual area E3 intersecting with the planned road on the traveling direction side are B2 'and B3'. The length of the road between A and B2 'is defined as the departure distance of the virtual area E2, and the length of the road between the line segments A and B3' is defined as the departure distance of the virtual area E3.

In the above-described embodiment, the traveling direction is calculated based on the change with time of the current position. However, the traveling direction may be detected by using a direction sensor based on geomagnetism or the like.

Although the transmitting station selection information of the above-described embodiment is VICS information by FM multiplex broadcasting, the present invention provides transmission of VICS information by beacon or RDS (Radio Data System) of the European Broadcasting Union. The present invention can be applied to a system in which information is transmitted from a station.

[0028]

As described above, according to the present invention, a transmitting station is selected based on the assumed distance until the mobile station leaves the coverage area. For this reason, there is a high possibility that the selected transmitting station will stay in the receivable area for a long time, and the number of times of changing the receiving frequency will be reduced.

When a transmitting station transmits information different from other transmitting stations, such as VICS, it is highly likely that the transmitting station will stay in the receivable area of the selected transmitting station for a long time. Is more likely to be given.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing a main operation of the embodiment.

FIG. 3 is a diagram showing area information of an FM multiplex broadcasting station.

FIG. 4 is a diagram illustrating a receivable area when the FM multiplex broadcasting station of the embodiment is shifted.

FIG. 5 is a diagram illustrating a distance measuring method according to another embodiment.

[Explanation of symbols]

 Reference Signs List 1 FM receiver 13 PLL circuit 15 Multiplex signal detection circuit 16 Control circuit (FM receiver) 2 Current position detector 21 Control circuit (Current position detector) 23 RAM 24 GPS positioning means 25 Map reproduction means 26 Display unit 27 Input unit

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Susumu Iida 3-201, Minamiyoshikata, Tottori-shi, Tottori F-term (reference) in Sanyo Electric Co., Ltd. BB01 CC07 9A001 CC05 HH34 JJ72 JJ77 JJ78

Claims (2)

[Claims] 1. A navigation device for selecting and receiving at least one of a plurality of transmitting stations for transmitting various service information, a positioning means for positioning a current position, and a radio wave transmitted from the transmitting station. Storage means for storing area information indicating a receivable area, and when there are a plurality of transmitting stations whose current position is within the area, it is assumed that the moving direction of the device is detected and that the device moves on a line extending in the moving direction. Selecting means for selecting a transmitting station in the order in which the predicted movement distance to the outside of the area becomes longer. 2. A navigation device for selecting and receiving one or more of a plurality of transmitting stations for transmitting various service information, a positioning device for positioning a current position, and a radio wave transmitted from the transmitting station. Storage means for storing area information indicating a receivable area and a planned movement route of the apparatus; and when there are a plurality of transmitting stations whose current position is within the area, the distance of the remaining planned movement path from the current position within the area. Selecting means for selecting a transmitting station in order of length of the navigation device.