JP4103782B2 - In-vehicle communication device - Google Patents

Description

  The present invention relates to an in-vehicle communication device for collecting automatic tolls when passing through a toll gate such as a toll road.

  As this type of device, there is an ETC in-vehicle device mounted on a vehicle in order to perform automatic fee collection. The ETC on-board device as a mobile station needs to be used under conditions that comply with the wireless standard because wireless communication is performed with a roadside device at the toll gate. This is a standard issued by the Japan Radio Industry Association, such as ARIB STD-T75. For example, a standard called eirp (equivalent isotropically radiated power) is specified for transmission characteristics and reception characteristics. ing.

This defines the upper and lower limits of the radio wave output and reception capability of the ETC on-board unit, and the gain (Gt: cable loss etc.) of the transmitting antenna and the output (Pt) of the transmitter or the sensitivity of the receiver. It is a value obtained by the product of (Pr).
For this reason, if it is assumed that the ETC on-board unit is mounted on various types of vehicles, there are a wide variety of antenna mounting positions and ETC on-board unit mounting positions, and as a result there is a difference in the distance between the antenna and the ETC on-board unit body. In addition, the length of the antenna feed line (cable) also varies, and as a result, there are many antenna gains.

Therefore, in order to satisfy the radio standard of ETC on-board equipment, conventionally, firstly, a method of preparing a large number of ETC on-board equipment having radio characteristics matched to the gain of the antenna, and secondly, antenna cables It is known to cope with such a method that the length of the ETC is fixed to the maximum length at the time of attachment, and the radio characteristics of the ETC on-board unit main body are fixed to one type.
In addition, there exists a thing as shown to patent document 1 as a related prior art which handled this kind of subject.
JP 11-331053 A

However, since it is necessary to manage various ETC on-board units for the first method described above, the management cost increases, and there is a possibility that foreign products may be mixed. Further, in the second method, there is a problem that, for example, if a cable is left depending on the vehicle type, an extra man-hour is required for the extra length processing of the cable.
And in the thing shown in patent document 1, although the solution is aimed at by providing a wireless repeater, since the cost increase is unavoidable compared with the structure which provides a cable, adoption in practical use may become difficult. is there.

  The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to be able to save the trouble of preparing a large number of models in advance or processing the remaining part of a long cable. The object is to provide an in-vehicle communication device.

  According to the first aspect of the present invention, when the antenna cable is connected to the connector of the main body, the communication control means reads the gain information of the antenna from the storage means provided in the antenna via the cable, and the gain The signal level adjusting means is adjusted and set so as to satisfy the communication standard according to the information to adjust the levels of the reception signal and the transmission signal of the communication means. As a result, the gain difference due to the type of antenna or the length of the cable to be connected can be set to a state conforming to the communication standard by adjusting the signal level adjusting means on the communication means side.

According to the second or third aspect of the invention, since the signal level is automatically adjusted by the attenuator or amplifier and the attenuation level or amplification factor is automatically adjusted by the communication control means, the consistency between the antenna gain and the communication means is determined by the communication standard. A configuration for adapting to the above can be realized easily and inexpensively.
According to the invention of claim 4, in each of the above inventions, the start of adjustment setting processing of the signal level adjusting means by the communication control means is performed by detecting the current flowing in the cable that the antenna is connected. The adjustment setting process can be surely performed when the cable is connected.

  According to the invention of claim 5, in the invention of claim 4, when the antenna cable is removed and another antenna cable is connected, the communication control means newly adjusts the signal level adjusting means. Since the setting process is performed, the adjustment setting process adapted to the gain information of the antenna after the replacement can be performed when the replacement is performed.

  According to the invention of claim 6, since the communication control means performs the communication processing of the signal related to the billing with the roadside device through the communication means, when using the ETC on-board device or other paid facilities, etc. It can be applied to an in-vehicle communication device to be used.

Hereinafter, an embodiment when the present invention is applied to an ETC vehicle-mounted device will be described with reference to the drawings.
FIG. 1 shows an electrical block configuration of the ETC vehicle-mounted device 1. The ETC vehicle-mounted device 1 includes an antenna unit 2 and a main body unit 3. An antenna substrate 4 is disposed in the antenna unit 2, and a coaxial cable 5 is connected to the antenna substrate 4. The coaxial cable 5 is connected in advance in various lengths so that the cable length can be arranged without excess or deficiency depending on the vehicle to be arranged and the arrangement position thereof.

  On the antenna substrate 4, a patch antenna 6, a memory 7 and the like are arranged together with other electronic components. The patch antenna 6 is for performing wireless communication with an ETC roadside device installed at a toll booth on a toll road. For example, the patch antenna 6 is suitable for transmission / reception of a signal having a frequency of 5.8 GHz for ETC communication. Settings are made. The patch antenna 6 is connected to the coaxial cable 5 via a high-frequency capacitor 8 so as to pass a signal of the above frequency.

  The memory 7 stores measurement results or predetermined data regarding the antenna gain of the antenna unit 2 as antenna gain information, and is shipped in a state of being written in a manufacturing factory, for example. In this case, since the antenna gain also depends on the length of the patch antenna 6 itself and the coaxial cable 5, the length of the coaxial cable 5 differs depending on the antenna placement position for the sake of optimal setting. Since it is difficult to set the data as uniform data, it is stored in the memory 7 in advance in this way.

  The memory 7 is connected to the coaxial cable 5 via a capacitor 9 and is provided so that antenna gain information can be read via the coaxial cable 5. Further, the memory 7 is connected to the coaxial cable 5 via the inductor 10 and is configured to be able to receive power from the main body 3 side via the coaxial cable 5. In this case, the capacitor 9 is set to a capacity that can pass through a carrier frequency of about several tens of KHz.

Next, the main body 3 is provided with a connector 12 to which the main body substrate 11 and the coaxial cable 5 are connected. The main board 11 has a power supply circuit 13, a CPU 14 as communication control means, an ETC communication module 15 as communication means, and a variable attenuator 16 as signal level adjusting means for adjusting the power of the transmitter and the sensitivity of the receiver. Has been implemented.
The power supply circuit 13 is connected to the connector 12 via the inductor 17, and can supply direct current from the connector 12 to the antenna unit 2 side via the coaxial cable 5. The access terminal of the CPU 16 is connected to the connector 12 via the capacitor 19, and the antenna gain information can be read from the memory 7 of the antenna unit 2 via the coaxial cable 5. The ETC communication module 15 is connected to the connector 12 via a high frequency capacitor 19. The CPU 14 is connected to an I / F circuit 20 that is connected to an external device such as a car navigation system and performs a cooperative operation.

  In this case, the coaxial cable 5 serves as the data path for ETC wireless communication, the data path for reading the antenna gain, and the power supply path for the three types of paths. Is set to a carrier frequency of about several tens of kHz, the power source has a direct current and the ETC wireless communication has a frequency of about 5.8 GHz. Therefore, the inductors 10 and 17 and the capacitors 8 and 10 and 18 respectively inserted therein are used. , 19, etc., data other than the necessary frequency is cut, so that it can be used as an independent path.

In the above description of the configuration, the configuration related to the gist of the present invention will be mainly described. For example, the configuration related to the IC card mounting unit and the signal exchange for billing processing, or the configuration related to the display device will be described. Is omitted, but a configuration similar to that of a general configuration is provided.
Next, an operation when the ETC on-vehicle device 1 having the above configuration is mounted on a vehicle and used will be described with reference to the flowchart of FIG.

  When the ETC on-vehicle device 1 is attached, the type of the antenna unit 2 and the length of the coaxial cable 5 are determined according to the type of the vehicle to be attached and the installation location desired by the user. The antenna unit 2 may be arranged on the dashboard or may be provided on the inner mirror unit on the upper part of the windshield, and the installation location of the main body unit 3 is various. When these arrangement positions are determined, the required length of the coaxial cable 5 is determined according to the distance between the two. The antenna unit 2 in which the length of the coaxial cable 5 is appropriately set is selected, these are arranged, and the coaxial cable 5 is connected to the connector 12 of the main body unit 3.

In the main body 3, when power is supplied, the CPU 14 starts its operation and executes a startup process according to the flowchart shown in FIG. 2. At this time, the power supply circuit 13 feeds DC power to the antenna unit 2 via the reactor 17, the connector 12, and the coaxial cable 5. As a result, the memory 7 is supplied with operating power.
First, the CPU 14 monitors the power supply circuit 13 to determine whether or not the antenna unit 2 is connected (steps S1 and S2). When it is detected that a current is flowing through the coaxial cable 5, the memory 7 is accessed to read the antenna gain information of the antenna unit 2, and the variable attenuator 16 is adjusted to an optimum value according to the read antenna gain information. By setting, the wireless standard is set to an optimum value (steps S3 and S4).

Thereafter, the CPU 14 determines whether or not a current is flowing through the coaxial cable 5 and performs a billing process based on an ETC process, that is, a signal from the antenna unit 2 when the connection state is confirmed. (Steps S5 and S6). If the power is not turned off, the above ETC process is repeatedly executed (steps S5 to S7).
When it is detected that no current flows through the coaxial cable 5 of the antenna unit 2 (steps S2 and S5), it is determined that the antenna is not connected and the power is turned on ( Steps S8 and S9) Return to step S1 and repeat the process. If it is detected that a current flows through the coaxial cable 5 of the antenna unit 2 while repeating this loop, the adjustment setting process of the variable attenuator 16 is performed as described above (steps S3 and S4). It will be executed (step S6).

  Since it operates as described above, when the installation work is performed for the first time, of course, the above operation is performed. However, after installation, the antenna unit 2 is removed or replaced for any reason. However, when the coaxial cable 5 is connected, the adjustment setting process of the variable attenuator 16 described above is performed, and the adjustment setting is automatically performed.

Therefore, it is possible to perform the attachment work without any trouble for the attachment worker or the user, and even when the coaxial cable 5 of the antenna unit 2 is disconnected from the connector 12 on the way, it is connected to the connector 12 again. By doing so, the adjustment setting process of the variable attenuator 16 adapted to the antenna gain information of the antenna unit 2 can be surely performed.
According to this embodiment, when the memory 14 is provided in the antenna unit 2 to store antenna gain information in advance and the CPU 14 detects that the coaxial cable 5 is connected to the connector 12 of the main body unit 3, Since the antenna gain information is read from the memory 7 via the cable 5 and the variable attenuator 16 is adjusted, an attenuation amount corresponding to the antenna gain can be set, so that the communication standard can be set. Thus, the mounting operation can be performed easily and quickly without bothering the mounting operator.

In addition, even when the antenna unit 2 is replaced, the CPU 14 automatically performs the above adjustment setting operation, so that it is surely set to a state that conforms to the communication standard without bothering the user or the operator. Will be able to.
The present invention is not limited to the above embodiment, and can be modified or expanded as follows.

In the above-described embodiment, the variable attenuator 16 is used as an attenuator. However, the present invention is not limited to this, and other attenuators can be used, and the amplification factor can be changed by the CPU 14 corresponding to the antenna gain information instead of the attenuator. An amplifier having a configuration that can be set can also be provided.
In addition to the ETC vehicle-mounted device 1, it can be applied to a vehicle-mounted communication device that is restricted by a communication standard and that needs to be adjusted in accordance with antenna installation conditions.

  Although it was set as the structure which recognizes the connection of the antenna part 2 by detecting an electric current, it is set as the structure which recognizes a connection state by receiving the signal transmitted from the antenna part 2 side which received power supply not only in this You can also.

1 is an electrical block diagram showing an embodiment of the present invention. Flow chart of adjustment process when antenna part is connected

Explanation of symbols

  In the drawings, 1 is an ETC vehicle-mounted device (vehicle communication device), 2 is an antenna unit, 3 is a main body unit, 4 is an antenna substrate, 5 is a coaxial cable, 6 is a patch antenna, 7 is a memory (storage means), and 11 is a main body. A substrate, 12 is a connector, 13 is a power supply circuit, 14 is a CPU (communication control means), 15 is an ETC communication module (communication means), and 16 is a variable attenuator (signal level adjusting means).

Claims (6)

An antenna for transmitting and receiving signals to and from the roadside machine;
Storage means provided in the antenna and storing gain information of the antenna;
A cable connected to this antenna,
A main body having a connector to which this cable can be connected;
A communication means for receiving a signal from the road device by the antenna via the cable connected to the connector provided in the main body and transmitting a signal to the road device;
A signal level adjusting means provided between the communication means and the connector for adjusting the level of the reception signal and the transmission signal;
Communication control means for performing communication processing with the roadside machine through the communication means,
When the antenna cable is connected to the connector, the communication control means reads the gain information of the antenna from the storage means, and the signal so that the reception level and transmission level of the communication means conform to a communication standard. An in-vehicle communication device characterized in that level adjustment means is adjusted and set. The in-vehicle communication device according to claim 1,
The in-vehicle communication apparatus, wherein the signal level adjusting means is an attenuator capable of setting an attenuation level. The in-vehicle communication device according to claim 1,
The in-vehicle communication device, wherein the signal level adjusting means is an amplifier capable of setting an amplification factor. The in-vehicle communication device according to any one of claims 1 to 3,
The in-vehicle communication device, wherein the communication control unit is configured to detect connection of the antenna by current and perform adjustment setting processing of the signal level adjustment unit. The in-vehicle communication device according to claim 4,
The communication control means is configured to perform adjustment processing of the signal level adjustment means when a change occurs in antenna gain information transmitted from the storage means of the antenna. . The in-vehicle communication device according to any one of claims 1 to 5,
The in-vehicle communication device characterized in that the communication control means performs communication processing of a signal relating to charging with a roadside device through the communication means.

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