JPH0122777B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to multiple types of in-vehicle communication devices installed on roadsides and the like and in vehicles such as buses, and an inductive communication method for transmitting data by inductive communication.

2. Description of the Related Art Conventionally, as an example of a communication method used between the road and the vehicle, there are methods shown in FIGS. 1 and 2. In Figure 1, 1 is a roadside communication device installed on the roadside, 2 is an on-vehicle communication device installed in a vehicle, and 2 is a roadside communication device installed on the roadside.
In the figure, A is an on-road transmission signal transmitted from the on-road communication device 1, and B is an on-vehicle response signal transmitted from the on-vehicle communication device 2 in response to the on-road transmission signal. Also, 3
is an unmodulated trigger signal using only the transmitting carrier,
4 is a response signal containing in-vehicle information. In this conventional example, if a vehicle equipped with an on-vehicle communication device 2 enters the communication area where the trigger signal 3 is being transmitted,
When the in-vehicle communication device 2 receives the carrier of the trigger signal 3 and detects that the carrier has stopped, it sends out a response signal 4 at the timing shown in FIG. 2 and ends the communication.

Next, Figures 3 and 4 show examples of communication methods that are developed from the conventional methods shown in Figures 1 and 2.
This will be explained with figures. 5 is a road communication device installed on the roadside, 6 is an in-vehicle communication device installed in a vehicle, and 4th is a road communication device installed on the roadside.
In the figure, A is a road device transmission signal transmitted from the roadside communication device 5, and B is an on-vehicle response signal transmitted from the vehicle-mounted communication device 6 in response to the roadside transmission signal. Also 7
numeral 8 is a trigger signal containing information such as on-road machine type, 8 is a response signal containing in-vehicle information, and 9 is a road-machine response signal to response signal 8. In this conventional example, when a vehicle equipped with an in-vehicle communication device 6 enters the communication area where the trigger signal No. 7 is being transmitted, the trigger signal No. 7 is received, and information such as the type of road vehicle included in the trigger signal is transmitted. Depending on the content, 8 at the timing shown in Figure 4.
A response signal is sent. When the roadside communication device 5 correctly receives the response signal 8, it sends out a roadside device response signal indicating completion of communication, and ends the communication between the vehicle and the road.

However, as systems using the conventional communication methods shown in FIGS. 1 to 4 are expanded, there is a demand to mix the communication methods shown in FIGS. 1 and 2 with the communication methods shown in FIGS. 3 and 4. is increasing. That is, since the on-vehicle communication device 2 and the serial communication device 6 coexist within the same system, it is necessary to also coexist the roadside communication device 1 and the roadside communication device 5. Therefore, even if the point where you want to communicate with the on-board communication device 2 and the on-board communication device 6 is the same location, it is necessary to install two types of roadside communication devices, which causes problems in terms of economy and construction. It's coming.

The present invention provides an inductive communication method that allows one type of on-road communication device to communicate with a plurality of vehicle-mounted communication devices that meet the following conditions.

The in-vehicle communication device 2 and the in-vehicle communication device 6 use the same carrier frequency.

The number of transmission characters, information arrangement, error control, etc. of the data communication transmitted from the in-vehicle communication device 2 and the in-vehicle communication device 6 to the on-road communication device may be different, but the modulation method is the same, and even if the modulation speed is different, it is an integral multiple. It must be.

Next, embodiments of the present invention will be described with reference to FIGS. 5 to 7.

Fig. 5 is an example of the system configuration according to this embodiment, and Fig. 6
The diagram shows the communication timing between the on-vehicle communication device 2 and the on-road communication device 10, and FIG. 7 shows the communication timing between the on-board communication device 6 and the on-road communication device 10.
This is the timing of communication with. 10 is a road communication device used in this implementation.

The roadside communication device 10 sends out a trigger signal 7 as a trigger signal. When a vehicle equipped with an in-vehicle communication device 2 enters this communication area, the in-vehicle communication device 2 does not distinguish between the carrier-only trigger signal 3 and the trigger signal 7 containing road information, so it performs the same processing as the carrier-only trigger signal 3. and sends out a response signal 4.
When the roadside communication device 10 receives a response signal from the vehicle-mounted communication device, it demodulates the data at a modulation rate that matches the maximum modulation rate of the plurality of vehicle-mounted communication devices used in this system. In other words, if the modulation speed of the in-vehicle communication device 2 is 2400 baud and the modulation speed of the in-vehicle communication device 6 is 4800 baud, the on-road communication device 10
Performs 4800 baud demodulation. As a result, the in-vehicle communication device 2
When a response signal is received from the transmitter, all received data is received and demodulated into 2-bit pairs. When the on-road communication device 10 receives and demodulates the signal in which the received data is all 2-bit pairs, this response signal is assumed to be from the vehicle-mounted communication device 2, compresses 2 bits into 1 bit, and performs information arrangement and error detection. and complete the communication. Note that if the on-vehicle communication device 2 and the on-vehicle communication device 6 have the same modulation speed, there is no particular problem because they can naturally be identified based on internal data (distinction such as system number).

Next, if a vehicle equipped with the on-vehicle communication device 6 enters the communication area where the trigger signal 7 is being sent, the seventh
Communication is completed according to the communication procedure shown in the figure (same as in FIG. 4).

As described above, according to the present invention, it is possible to communicate with multiple types of in-vehicle communication devices with different transmission speeds using one roadside communication device, so there is no need to install multiple roadside communication devices. It has great advantages in terms of economy and ease of construction.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional inductive communication method, FIG. 2 is a communication timing diagram in the same method, FIG. 3 is a schematic diagram of another conventional inductive communication method, and FIG. 4 is a communication timing diagram in the same method. FIG. 5 is a schematic diagram of an inductive communication method according to an embodiment of the present invention, and FIGS. 6 and 7 are communication timing diagrams of the same method. 2...In-vehicle communication device, 3...Trigger signal, 4...
Response signal, 6... Vehicle-mounted communication device, 7... Trigger signal, 8... Response signal, 9... Road device response signal, 1
0... Road communication device.

Claims (1)

[Claims] 1. If there are multiple types of in-vehicle communication devices and road-side communication devices that use the same carrier frequency and have different modulation speeds by integral multiples, the received demodulation speed is adjusted to the maximum modulation speed of the in-vehicle communication device that communicates, and the An inductive communication method characterized in that the type of the received vehicle-mounted communication device is determined from the code structure of received data, and communication is performed in accordance with the vehicle-mounted communication device.