JPH05129994A - Electromagnetic induction communication test equipment - Google Patents

Abstract

PURPOSE:To provide the electromagnetic induction communication test equipment able to conduct the electromagnetic induction communication test without provision of an antenna while not being affected of an electromagnetic field. CONSTITUTION:A communication signal is coupled between an output transformer in a transmission on-vehicle communication equipment 16 and a 1st matching transformer 2 of a master equipment 1 through matching to attain impedance conversion. Furthermore, a decided communication level is set by a variable resistor of attenuators 4, 5, 6 and a changeover switch 3 is selected to select the communication level of each adjustment item. Then the master set 1 is coupled with a matching transformer in an on-road equipment 10 through a 2nd matching transformer 7 to output a signal whose impedance is converted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic induction communication test device for a road communication device and a vehicle communication device in a bus operation management system which is generally known.

[0002]

2. Description of the Related Art Conventionally, in a communication test in a weak electric wave such as electromagnetic induction communication, spatial communication is performed in an environment where the influence of an electromagnetic field is small, and a reception level in a roadside communication device or an in-vehicle communication device is adjusted.

FIG. 2 shows the configuration of a conventional communication test device.
In FIG. 2, reference numeral 20 is a communication test room that is less affected by electromagnetic fields, 32 is an in-vehicle communication device for transmission mounted on a route bus, and includes a data generator 34, a data transmitter 35, and an output transformer 33. It is connected to the vehicle-mounted antenna 31 and transmits the data via the on-road antenna 30 to the on-road communication device 23 for adjustment installed on the road. The adjusted roadside communication device 23 includes an input transformer 26, a reception amplifier 25, a reception gain adjustment variable resistor 27, a tuning adjustment transformer 28,
It is composed of a level detection circuit 24 and is connected to a road antenna 30. Reference numeral 21 is a level meter connected to the level detection circuit 24 to measure the reception level, 22 is an oscilloscope connected to the level detection circuit 24 to measure the reception waveform, 29 is an electric field strength meter for determining the distance between the roadside antenna 30 and the vehicle-mounted antenna 31. Is.

The measuring method of the conventional example will be described.
In FIG. 2, the measurement is performed in the communication test room 20 which is not affected by the electromagnetic field. First, a method of adjusting the tuning frequency will be described. The in-vehicle antenna 31 is fixed and data is transmitted from the in-vehicle communication device 32 for transmission. At the position where the electric field strength is 80 dBμV / m by the electric field strength meter 29, the on-road antenna 3
With 0 fixed, the tuning adjustment transformer 28 is adjusted to maximize the received waveform while observing the received waveform with an oscilloscope connected to the level detection circuit 24 in the on-road communication device 23 to be adjusted.

Next, the receiving gain adjusting method will be described. Similarly to the above, the electric field strength is 29d with the electric field strength meter 29.
The on-road antenna 30 is fixed at the position of B μV / m, and the variable resistor 27 is adjusted to a predetermined reception level while measuring the reception level with the level meter 21 connected to the level detection circuit 24.

Further, a method of confirming received data will be described. In the same manner as above, the electric field strength measured by the electric field strength meter 29 is 9
The on-road antenna 30 is fixed at the position of 0 dBμV / m, and the communication fixed data is confirmed by the normal communication counter and the abnormal communication counter in the level detection circuit 24.

As described above, conventionally, the communication test is conducted by spatial communication by changing the communication level while moving the antenna interval.

[0008]

However, the above-mentioned conventional communication test method requires a special communication test room in order to perform the test at a place where the test is not affected by the electromagnetic field.
Further, there is a problem that the field intensity must be measured and the antenna must be moved for each measurement item in order to set the antenna interval using the electric field intensity meter when adjusting the reception level.

The present invention solves such conventional problems, and it is an object of the present invention to provide an excellent electromagnetic induction communication test apparatus which is not affected by an electromagnetic field and can perform an electromagnetic induction communication test without using an antenna. It is intended.

[0010]

In order to achieve the above-mentioned object, the present invention replaces a roadside antenna and a vehicle-mounted antenna with
A matching transformer and an attenuator are provided to connect the in-vehicle communication device and the road communication device directly with this device.

[0011]

With the above structure, the communication level value can be set by setting the attenuator constant, and the communication test can be carried out without being affected.

[0012]

1 shows the construction of an embodiment of an electromagnetic induction communication test apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes this device, which includes a first matching transformer 2 provided on the signal input side, a changeover switch 3, an attenuator 4, an attenuator 5, an attenuator 6, and a second matching transformer 7 provided on the signal output side. It is composed of. The attenuator 4, the attenuator 5, and the attenuator 6 determine the communication level value during the communication test, and are set to different level values. Further, the second matching transformer 7 is for transmitting the impedance-exchanged signal to the on-road communication device for adjustment, and the first matching transformer 2 is for receiving the signal from the in-vehicle communication device for transmission by impedance exchange. Is. Changeover switch 3
Is for switching the attenuator 4, the attenuator 5, and the attenuator 6 for each test item. Reference numeral 16 denotes an in-vehicle communication device for transmission mounted on a route bus, and the data generation unit 1
7 and the data transmitter 18 and the output transformer 19, and the output transformer 19 is connected to the first matching transformer 2 so that the on-vehicle communication device 16 for transmission can transmit a signal to the device 1. Adjusted roadside communication device 10
Is composed of an input transformer 15, a receiving amplifier 12, a receiving gain adjusting variable resistor 13, a tuning adjusting transformer 14, and a level detecting circuit 11. By connecting the input transformer 15 to a second matching transformer 7, The adjustment roadside communication device 10 can receive a signal from the device 1. A level meter 8 is connected to the level detection circuit 11 to measure the reception level. An oscilloscope 9 is connected to the level detection circuit 11 to measure a received waveform.

Next, the operation of the above embodiment will be described. In the above embodiment, when the attenuator 4 switches the changeover switch 3 to the attenuator 4, the input level of the on-the-road communication device 10 for adjustment is the conventional tuning frequency adjustment. The electric field strength at the on-road antenna is set to be the same as the communication level value of 80 dBμV / m. When the attenuator 5 switches the selector switch 3 to the attenuator 5, the input level of the on-road communication device 10 for adjustment has a field strength of 8 on the road antenna at the time of the conventional reception gain adjustment.
It is set to be the same as the communication level value of 5 dBμV / m. Also, when the attenuator 6 switches the changeover switch 3 to the attenuator 6, the input level of the on-road communication device 10 to be adjusted becomes equal to the communication level value of 90 dBμVm when the electric field strength at the road antenna in the confirmation of the conventional communication test data is 90 dBμVm. Is set to be. In the tuning frequency adjustment method, the on-vehicle communication device 16 for transmission transmits to the first matching transformer 2. The changeover switch 3 is switched to the attenuator 4 side, and the tuning adjustment transformer 14 in the on-adjustment roadside communication device 10 is adjusted so that the oscilloscope 9 maximizes the received waveform. In the receiving gain adjusting method, the variable resistor 13 is transmitted in the same manner as described above to switch the changeover switch 3 to the attenuator 5 side and set the variable resistor 13 to the receiving level determined by the level meter 8 connected to the level detecting circuit 11. adjust. In the same manner as described above, the changeover switch 3 is switched to the attenuator 6 side and the communication fixed data is confirmed by the normal communication counter and the abnormal communication counter in the level detection circuit 11.

As described above, according to the above-described embodiment, by connecting the on-road communication device for adjustment 10 and the on-vehicle device for transmission 16 to the device 1, the device can be operated without the spatial communication test in the communication test room. A communication test can be performed by direct connection, and it has the effect that it can be tested in a narrow range without being affected by electromagnetic fields.

[0015]

As described above, according to the present invention,
Since the antenna is not used, the communication test can be performed without being affected by the electromagnetic field, and the communication level can be set at the communication level for each test item only by switching the switch by setting the communication level value of the attenuator. Therefore, the operation is easy. Further, since the in-vehicle communication device for transmission is directly connected to this device and the on-road communication device for adjustment, various effects such as a communication test can be obtained even under a special environment.

[Brief description of drawings]

FIG. 1 is a block diagram and a connection diagram of an embodiment of an electromagnetic induction communication test device of the present invention.

FIG. 2 is a block diagram and a connection diagram showing an example of a conventional electromagnetic induction communication test device.

[Explanation of symbols]

 1 Electromagnetic Induction Communication Test Device 2 First Matching Transformer 3 Changeover Switch 4, 5, 6 Attenuator 7 Second Matching Transformer 8, 21 Level Meter 9, 22 Oscilloscope 10, 23 Adjustable Roadside Communication Device 11, 24 Level Detection Circuit 12,25 Receiving amplifier 13,27 Receiving gain adjusting variable resistor 14,28 Tuning frequency adjusting transformer 15,26 Input transformer 16,32 In-vehicle communication device for transmission 17,34 Data generator 18,35 Data transmitter 19 , 33 Output transformer 20 Communication test room 29 Electric field strength meter 30 Roadside antenna 31 In-vehicle antenna

Claims (2)

[Claims] 1. A transmitter for transmitting a communication test signal, a receiver for receiving a signal from the transmitter, a first matching transformer connected to an output section of the transmitter, and an input section of the receiver. The second matching transformer and the first matching transformer
And an attenuator provided between the second matching transformer and an electromagnetic induction communication test device, wherein the matching level and the attenuator are used to adjust the reception level of the spatial communication test by electromagnetic induction. 2. An electromagnetic induction characterized in that a plurality of attenuators are provided, a changeover switch is connected between the first and second matching transformers and the attenuator, and the attenuator can be changed for each item of the communication test. Communication test equipment.