JPH10276170A - Intra-vehicle communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system which is proof against noise and which can realize the high speed transmission of data by connecting one coaxial cable and plural devices by a coupler. SOLUTION: One coaxial cable 6 is used as a signal line and the respective devices 5-1, 5-2, 5-3... are connected to the cable 6 through the coupler 7 and therefore wiring is simplified. Thus, a signal can be speeded up and transmission by a spectral diffusion system is realized by using the cable 6. Thus, the influence of external noise and influence given to outside can be reduced. The respective devices 5-1, 5-2, 5-3... can be installed in arbitrary places by connecting the respective devices 5-1, 5-2, 5-3< with the cable 6 by using the coupler 7. When the device 5-1 executes an operation for displaying a fare, for example, a base band signal containing the control code of fare display is spectrum- diffused and modulated and is transmitted on the cable 6. Thus, the signal displays the fare in the device 5-2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vehicle communication system used for communication between devices mounted on a vehicle such as a bus.

[0002]

2. Description of the Related Art Conventionally, communication between devices mounted on a vehicle such as a bus uses a dedicated line such as RS-232C or RS-422 or a power line commonly connected to each device.

FIG. 4 is a perspective view showing connections between devices when a dedicated line 2 such as RS-232C or RS-422 is used. RS-232 between devices 1-1, 1-2, 1-3, ...
C, a dedicated line 2 such as RS-422 is wired. A power line 3 is connected to each of the devices 1-1, 1-2, 1-3,.

FIG. 5 is a perspective view showing connections between devices when the power supply line 3 is used. When the power supply line 3 is also used as a signal line, FM modulation, AM modulation, or spread spectrum modulation / demodulation is used as a signal transmission method. The transmission by the FM modulation and the AM modulation method is described in, for example,
The transmission by the spread spectrum modulation / demodulation method is disclosed in, for example, JP-A-7-50619.

[0005] It is to be noted that a device 1-mounted on a vehicle such as a bus, etc.
1, 1-2, 1-3,... Include, for example, a fare display device, a numbered ticket issuing device, and an operation panel for operating these devices.

[0006]

However, the above-mentioned conventional in-vehicle communication system has the following problems.

In the system using the dedicated line 2 such as RS-232C and RS-422, the wiring becomes complicated when the number of the devices 1 installed in the vehicle increases, so that the work efficiency at the time of construction and maintenance deteriorates. Resulting in. In addition, this kind of dedicated line 2 does not provide sufficient shielding against noise, which causes a malfunction of the apparatus. Furthermore, RS-2
For 32C and RS-422, since a protocol for transmitting a signal is specified by a standard, it is impossible to apply a spread spectrum method which is generally said to be resistant to noise. Couldn't do enough.

In a system in which the power supply line 3 is commonly used as a signal line, a signal is transmitted between the devices by the power supply line 3, so that the wiring is simplified. In particular, FM modulation and AM modulation are easily affected by noise. In addition, FM modulation and AM
Even in a spread spectrum modulation / demodulation system which is said to be more resistant to noise than a modulation system, it is affected or affected by a signal of a similar system or broadband noise.

The power line 3 is not preferable as a medium for transmitting data at high speed.

In view of the above circumstances, an object of the present invention is to provide an in-vehicle communication system that can simplify wiring, is resistant to noise, and can transmit data at high speed.

[0011]

According to the present invention, there is provided an in-vehicle communication system for performing communication between devices mounted on a vehicle such as a bus by a spread spectrum method. A single coaxial cable laid only in the vehicle and used for transmission of signals between the devices, and provided for each of the plurality of devices to electrically connect the devices and the coaxial cable. And a coupler.

According to this configuration, only one dedicated coaxial cable is used for communication between the devices, and the connection between the coaxial cable and each device is performed by the coupler.

[0013] Therefore, since only one coaxial cable is required for communication, the wiring is simplified. Further, by using a coaxial cable, high-speed transmission of a signal and transmission by a spread spectrum method become possible, and the influence of external noise and the influence on the outside can be reduced. In addition, since the connection between each device and the coaxial cable is performed by the coupler, the installation location of each device is not restricted and can be installed at an arbitrary location.

[0014]

FIG. 1 is a block diagram showing a configuration of an embodiment of a communication system in a vehicle according to the present invention.

The communication system in a vehicle according to this embodiment is
It is as follows.

(A) The signal line is physically separated from the power supply line 3 as a separate system.

(B) A coaxial cable 6 is used as a signal line, and one cable is laid in the vehicle.

(C) Coaxial cable 6 and devices 5-1 and 5-
, 5-3,... Are connected via the coupler 7.

One coaxial cable 6 is used as a signal line, and each of the devices 5-1, 5-2, 5
-3,... Via the coupler 7 simplifies the wiring. In addition, the use of the coaxial cable 6 enables high-speed transmission of a signal and transmission by a spread spectrum method, and can reduce the influence of external noise and the influence on the outside. By connecting each device 5-1, 5-2, 5-3,... To the coaxial cable 6 using the coupler 7, each device 5-1, 5-2, 5-3,. Can be installed at any location.

FIG. 2 shows a coaxial cable 6 and a coupler 7.
FIG. 4 is a cross-sectional view showing connection with the circumstance. As shown in this figure, a short coaxial cable 8 connected to the device 5 by a coupler 7 is supported at right angles to the coaxial cable 6. In this case, the tip of the core wire 8a of the coaxial cable 8 is in contact with the core wire 6a of the coaxial cable 6, and the tip of the shield 8b of the coaxial cable 8 is in contact with the shield 6b of the coaxial cable 6. The coaxial cable 8 is connected by the coupler 7.
Before connecting the coaxial cable 6 and
It is needless to say that a hole up to the core wire 6a is formed at the connection point of the above, and the coating of the end portion of the coaxial cable 8 is removed.

Each of the devices 5-1, 5-2, and 5-3 has, for example, a configuration as shown in the block diagram of FIG. In this case, the device 5-1 is an operation panel provided in the driver's seat, the device 5-2 is a fare display device, and the device 5-3 is a numbered ticket issuing device. In the figure, a device 5-1 includes an operation unit 10 including various switches and display lamps, and the operation unit 10 and the control unit 12
And a control unit 12 and a transmission / reception unit 13. The control unit 12 receives a switch signal from the operation unit 10 via the interface 11, generates a baseband signal including a corresponding control code, and supplies the baseband signal to the transmission / reception unit 13. The transmission / reception unit 13 performs spread spectrum modulation on the baseband signal from the control unit 12 and transmits the signal to the coaxial cable 6. Also, the transmitting / receiving unit 13
Receives the signal transmitted on the coaxial cable 6, performs spread spectrum demodulation, and outputs a signal obtained by the spread spectrum demodulation.

The device 5-2 includes a fare display unit 15, and an interface 1 for connecting the fare display unit 15 and the control unit 17.
6, a control unit 17, and a transmission / reception unit 18. The transmission / reception unit 18 modulates and demodulates the signal by spread spectrum modulation and demodulation. The control unit 17 takes in the signal output from the transmission / reception unit 18 and, when judging that the control code included in the signal is for displaying the fare, performs the display control according to the control code. After performing the display control, a signal notifying the fact is transmitted from the transmission / reception unit 18 onto the signal line 6.

The device 5-3 includes a numbered ticket issuing unit 20, an interface 21 for connecting the numbered ticket issuing unit 20 and the control unit 22, a control unit 22, and a receiving unit 23.
The receiving section 23 performs signal demodulation by spread spectrum demodulation. The control unit 22 takes in the signal output from the receiving unit 23, and when determining that the control code included in the signal is for issuing a numbered ticket, performs the ticketing control according to the control code.

In such a configuration, when an operation for displaying a fare is performed in the device 5-1, a baseband signal including a control code for displaying the fare is spread-spectrum modulated and transmitted onto the coaxial cable 6. . Coaxial cable 6
The signal transmitted above is taken into only the device 5-2, and the fare is displayed according to the control code. On the other hand, when the operation of issuing the numbered ticket is performed in the device 5-1, the baseband signal including the control code for issuing the numbered ticket is spread-spectrum modulated and transmitted onto the coaxial cable 6. The signal transmitted on the coaxial cable 6 is taken into only the device 5-3, and a numbered ticket is issued according to the control code.

As described above, the in-vehicle communication system according to this embodiment includes the coaxial cable 6 as a signal line and the power line 3
Are physically separated as separate systems, one coaxial cable 6 is laid in the vehicle, and the coaxial cable 6 is connected to each device 5-1, 5-2, 5- 3. Connection with ... was made.

Therefore, wiring is simplified, and work efficiency during construction and maintenance is improved. In addition, the use of a coaxial cable enables high-speed signal transmission and transmission using a spread spectrum method, and further reduces the influence of external noise and the influence on the outside.
Also, since there is no restriction on the installation location of each device 5-1, 5-2, 5-3,..., The degree of freedom of installation can be increased.

[0027]

As described above, according to the present invention,
The following effects can be obtained.

(A) Since a coaxial cable is used as a signal line dedicated to communication, the influence of external noise and the influence on the outside are significantly reduced as compared with the case where a power line that generates a lot of noise is also used as a communication line. In addition to this, high-speed transmission of a signal and transmission by a spread spectrum method become possible, and high communication reliability can be maintained. (B) Since each device is connected to a coaxial cable using a coupler, wiring can be simplified, and work efficiency during construction and maintenance is improved.

(C) Since each device can be connected to any part of the coaxial cable by the coupler, the degree of freedom of the installation location of each device is increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of an embodiment of an in-vehicle communication system according to the present invention.

FIG. 2 is a cross-sectional view showing a connection between a signal line and a coupler of the in-vehicle communication system according to the embodiment;

FIG. 3 is a block diagram illustrating a schematic configuration of each device of the in-vehicle communication system according to the embodiment;

FIG. 4 is a perspective view showing an appearance of a conventional in-vehicle communication system.

FIG. 5 is a perspective view showing the appearance of a conventional in-vehicle communication system.

[Explanation of symbols]

 5-1, 5-2, 5-3 Equipment 6 Coaxial cable 7 Coupler

Claims (1)

[Claims] An in-vehicle communication system for performing communication between devices mounted on a vehicle such as a bus by a spread spectrum method, wherein the communication system is used only for transmitting signals between the devices and is installed in the vehicle. An in-vehicle communication system, comprising: a coaxial cable; and a coupler provided for each of a plurality of devices and electrically connecting the device and the coaxial cable.