JPH0660297A - Moving body navigation system and moving body broadcasting receiver - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent erroneous switching due to local topography, tunnels, noise, etc. of mobile broadcast receivers. According to the mobile navigation system of the present invention, broadcasting station data and service area data (or electric field intensity distribution data) of the conventional map data can be superimposed and displayed. It is also possible to store those data and control the broadcast receiver to change the tuning to the broadcasting station of the service area in synchronization with the movement of the mobile object to the next service area. For the service area data, the direct coverage area of the radio wave is obtained from the terrain data and the antenna height of each broadcasting station, and an approximate service area is calculated in consideration of the broadcasting power and the theoretical propagation attenuation based on the area. , Which is sequentially corrected by the measured data is used. The broadcasting station data includes at least one of a broadcasting frequency band, a modulation method, a used frequency, and a category of interest to the user (affiliation network, specialized broadcasting contents, used language, etc.).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadcast receiver and a navigation system used in a mobile body (automobile, motorcycle, ship, etc.), and more particularly to a system and a receiver for selecting an optimum broadcast station as the user moves.

[0002]

2. Description of the Related Art A broadcast receiver mounted on a moving body such as an automobile suffers from poor electric field strength due to the distance between the broadcasting station and the terrain as the moving body travels, and the receiving station (frequency) fails to receive. In the European Broadcasting Union (EBU), a system that automatically switches to an alternative station when it becomes available is used. This is FM on the radio
RDS is a method of transmitting digital data by being multiplexed with broadcasting.
(Radio Data System).

The RDS requires facility investment and maintenance of the operating system on the broadcasting station side, and cannot be used in Japan or other places where such facilities are not maintained. In order to solve this problem, the present inventors have proposed, in Japanese Patent Application No. 3-346460 "broadcast receiver", data of all broadcasting stations, that is, transmission frequencies, in advance.
Data such as geographical position, main roads nearby, category (affiliation network, specialized broadcast content, language), etc. is stored, and the data is used to automatically follow the broadcast of a specific category according to the driving. I proposed the method to do.

[0004]

[Problems to be Solved by the Invention] Japanese Patent Application No. 3-34646
In No. 0, the tuning switching of the receiver is performed by the deterioration of the electric field strength of the frequency currently being received, the deterioration of the sound quality due to human judgment, or the method activated by geographical information. In this case, there is a defect that switching is activated due to local topography, deterioration of electric field strength due to tunnels, deterioration due to ambient radio noise, and the like. The present invention solves such a problem.

[0005]

[Means for Solving the Problems]

(1) In the mobile navigation system according to claim 1, it is possible to display the broadcast station data and the service area data (or electric field intensity distribution data) on the map data for the mobile navigation system in an overlapping manner. There is. This allows the tuning to be manually changed to the corresponding broadcasting station as the mobile unit moves to the next service area. (2) The mobile navigation system according to claim 2 stores map data for the mobile navigation system, broadcast station data, and service area data (or electric field intensity distribution data) of the map data. Synchronously with moving to a service area, it provides or controls information to a broadcast receiver to change tuning to a broadcast station in that service area. (3) In the mobile body navigation system according to claim 3, in (1) or (2), the direct coverage area of the radio wave is calculated as the service area data from the terrain data and the antenna height of each broadcasting station. Based on the direct coverage area, an approximate service area is calculated in consideration of the broadcasting power and the theoretical propagation attenuation amount, and the approximate service area is sequentially corrected by actual measurement data. (4) In the mobile broadcast receiver according to claim 4, the broadcast information can be tuned to the broadcasting station in the corresponding service area by or under the control of the information provided by the mobile navigation system according to (2). (5) In the mobile navigation system according to claim 5, in any one of (1), (2), and (3), the broadcasting station data includes at least one of the following. Broadcast frequency band, modulation method, frequency used, categories of interest to the user (affiliation network, specialized broadcast content, language used, etc.).

[0006]

EXAMPLE FIG. 1 is an example of a direct area calculated by a computer using the geographical feature data of the Geographical Survey Institute and the antenna height of a broadcasting station. In the figure, A and B are broadcasting antennas with a height of 50 m, and 1a and 1b are direct reach areas. It is a contour line of the electric field intensity of the closed curves 3a and 3b in each area. Also shown in the figure are contour lines 2 and roads 4 to 6 at an altitude of 200 m.

In practice, an approximate service area is calculated and used in these direct areas 1a and 1b in consideration of the broadcasting power of each antenna and the theoretical propagation attenuation. In addition, although the approximate service area actually expands a little more due to diffraction or the like, the service area of each broadcasting station can be determined at the national level as a first approximation. Further, the service area data is completed by sequentially correcting it with collection of actual measurement data to improve accuracy.

It is easy to add such service area data to the navigation map data. Map data is often created by adding the necessary characters and symbols to figures using minute vectors or bit patterns. Various methods can be used to describe the service area, but as an example, the service area can be composed of start point and end point data on the raster.

A service area is created for each broadcasting station, and depending on the point, it may belong to a plurality of service areas even in the same category, or may not belong to any service area at all. The area that does not overlap or does not belong at all may be determined by actual measurement. In the navigation system, a map of a specific traveling area is displayed on the display, and the position of the own vehicle is displayed on the map. If you select a category, you can display the broadcasting station data of that category and its service area on the display. The broadcast station data includes at least one of a broadcast frequency band, a modulation method, a used frequency, and a category of interest to the user (affiliation network, specialized broadcast content, used language, etc.). With such a map, vehicle position, broadcasting station data and service area display, tuning can be manually switched to an alternative broadcasting station at the boundary of the service area, or from the control unit in the navigation system. The receiver can be switched automatically by controlling the broadcast receiver or by the information of the navigation system. In the case of automatic, the display of the service area is not always necessary.

By doing so, it is possible to prevent erroneous switching of the tuning even if the received electric field strength and the sound quality are deteriorated due to local topography, tunnels, noises and the like.

[0011]

As the mobile broadcast receiver moves, the broadcast stations in the desired category can be sequentially and accurately switched to continue reception. In particular, it is possible to prevent erroneous switching due to local topography, tunnels, noise, and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a broadcast radio wave direct area calculated by a computer based on topographical data and a broadcasting station antenna height.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H03J 5/00 H 8523-5K H04B 1/16 C 7240-5K

Claims (5)

[Claims] 1. A mobile navigation system capable of displaying broadcast station data and service area data (or electric field intensity distribution data) of the map data for the mobile navigation system in an overlapping manner. 2. Map data for a mobile navigation system, broadcast station data, and service area data (or electric field strength distribution data) of the map data are stored and synchronized when the mobile body moves to the next service area. And providing information for controlling or controlling the broadcast receiver to change the tuning to the broadcast station in its service area. 3. The mobile navigation system according to claim 1 or 2, wherein the service area data calculates a direct coverage area of a radio wave from topographical data and an antenna height of each broadcasting station, and also includes the direct coverage area. In addition, the approximate service area is calculated in consideration of the broadcast power and the theoretical propagation attenuation, and the approximate service area is sequentially corrected by the measured data. 4. A mobile broadcast receiver that tunes to a broadcast station in a corresponding service area according to or controlled by the information of the mobile navigation system according to claim 2. 5. The mobile navigation system according to claim 1, 2 or 3, wherein the broadcast station data includes at least one of the following. Broadcast frequency band, modulation method, frequency used, categories of interest to the user (affiliation network, specialized broadcast content, language used, etc.).