JPH11298489A - Etc onboard tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic toll collection ETC onboard tester by which a test is conducted by generating a received signal in a simulating way that reflects an actual vehicle drive state without driving the vehicle actually. SOLUTION: An ETC onboard tester body 16 generates a signal to be sent to an ETC on-vehicle device 19. A fading generating section gives fading to the signal and the resulting signal is fed to an antenna 17. The antenna 17 is contained in a shield case with the ETC onboard device to eliminate the effect of an external radio wave and an internally reflected radio wave. A signal demodulated by the ETC onboard device is fed to a bit error measurement section 14, where the signal is compared with a basic bit pattern from a signal generating section. An arithmetic control section 15 calculates a bit error rate, based on the comparison result and displays it. Furthermore, a reception section 13 detects reception strength of a signal received by the antenna. The arithmetic control section 15 obtains transmission power of the ETC onboard device, based on the reception strength detected by the reception section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ETC on-board equipment tester.

[0002]

2. Description of the Related Art ETC (Electronic Toll Collection)
The system is intended to be able to charge and collect tolls without stopping vehicles in order to alleviate congestion at tollgates on expressways. In this system, an ETC roadside device is provided at the entrance and exit of a highway, and an ETC on-vehicle device is mounted on the vehicle. The information is written by the roadside device, and the information is read out at the exit, and charging is performed. Collection of the fee is performed separately by a credit guard or the like, or is performed on the spot by a non-contact IC card or the like.

The E used in such an ETC system
Conventionally, the test of the TC vehicle-mounted device has been performed as follows using the device shown in FIG.

First, a signal is transmitted from the on-board ETC unit 41, and the transmission power is measured by a power meter 42 or a spectrum analyzer.

Further, the frequency of the transmission signal is measured using the frequency counter 43.

Then, a signal from the bit error measuring device 44 is transmitted to the ETC on-board unit 41, and the ETC on-board unit 41
By returning the demodulated signal to the bit error measuring device 44, the bit error rate is measured.

As described above, the conventional test includes the power meter 42, the frequency counter 43, and the bit error measuring device 4
4 is used, and no special ETC in-vehicle equipment tester is known.

[0008]

The on-board ETC device is mounted on a vehicle as its name implies. And ETC
Since the system aims at not stopping the vehicle, it is premised that the on-board ETC device is used while the vehicle is running.

However, the test of the conventional ETC on-vehicle device is not performed by actually running the vehicle,
Only the test of the ETC on-board unit in the stopped state is performed. When actually mounted on a vehicle, there are a plurality of radio wave propagation paths between the roadside device and the onboard device as shown in FIG. 5 (mainly those directly received and those due to road surface reflection). , Fading has occurred in the received signal. Also,
The transmission / reception state also changes due to the operation of the wiper and the like. Therefore, the conventional test method has a problem that it is unclear whether required performance is obtained when the ETC on-vehicle device is mounted on a vehicle. In addition, there is a problem that a test facility becomes large-scale in order to perform a test by actually running a vehicle equipped with an on-board ETC device.

An object of the present invention is to provide an ETC on-vehicle equipment tester which can perform a test by generating a reception signal while the vehicle is running, without actually running the vehicle. And

[0011]

According to the present invention, there is provided a signal generating means for generating a transmission signal receivable by an on-board ETC device for performing a performance test of an on-board ETC device mounted on a vehicle; Fading is generated in the transmission signal generated by the signal generating means, and fading is generated by the fading generating means for simulating a reception state of the on-board ETC device when the vehicle is traveling, and fading is generated by the fading generating means. An ETC in-vehicle equipment tester having an antenna for transmitting a transmission signal is obtained.

According to the present invention, the antenna and the ETC on-vehicle device are housed inside, a shield case for blocking external radio waves and preventing reflection of internal radio waves, and demodulated by the ETC on-vehicle device. And a cable for extracting the demodulated signal to the outside of the shield case.

Further, according to the present invention, the signal generation means has reference pattern generation means for generating a reference pattern, and is connected to the reference pattern generation means and the cable, and the reference pattern and the demodulated signal are output. And an ETC on-vehicle equipment tester characterized by having a bit error measurement unit for measuring a bit error by comparing

In this case, the transmission output is reduced stepwise during the bit error measurement, and the reception sensitivity is calculated by calculating the reception input level of the vehicle-mounted ETC unit from the transmission output when the bit error becomes worse than a predetermined value. Can be.

Still further, according to the present invention, the antenna is a transmission / reception antenna, and further includes arithmetic control means for calculating the reception sensitivity of the on-board ETC device from the strength of a signal received by the transmission / reception antenna. An ETC on-board equipment tester is obtained.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an ETC according to an embodiment of the present invention.
2 shows an in-vehicle device tester. This ETC in-vehicle equipment tester
Signal generator 11, fading generator 12, receiver 1
3. ETC in-vehicle equipment tester main body 16 including bit error measuring unit 14 and arithmetic control unit 15, and transmitting / receiving antenna 1 connected to fading generating unit 12 and receiving unit 13.
7 with a built-in 7 and a shield case 1
8 has a cable 20 for connecting the on-board ETC device 19 and the bit error measuring unit 14.

The signal generator 11 generates a signal having the same frequency as the transmission signal transmitted by the roadside device of the ETC system,
The signal is modulated by a predetermined modulation signal (reference pattern) and output to the fading generator 12.

The fading generator 12 adds fading simulating a radio wave propagation path to the signal from the signal generator 11 and outputs the signal to the antenna 17 as described later.

The antenna 17 radiates a signal from the fading generator 12 inside the shield case 18. The shield case 18 blocks external radio waves, absorbs radio waves radiated from the antenna 17 by a radio wave absorber attached to the inner wall thereof, and prevents internal reflection. As a result,
The antenna of the on-board ETC device 19 receives only the signal radiated from the antenna 17.

The receiving unit 13 receives the E
Receiving a signal from the TC on-board unit 19 and its strength (power)
Is measured.

The bit error measuring section 14 is provided with the signal generator 1
4 is compared with the demodulated signal from the on-board ETC device transmitted via the cable 20, and the bit error is measured.

The operation control unit 15 controls each unit and performs various operations.

Next, the fading generator 12 will be described in detail.

Between the actual roadside device and the ETC on-board device,
Fading occurs in which the amplitude has a Rice distribution. This is because the signal transmitted from the roadside device reaches the ETC on-vehicle device mainly by a route that is directly received and a route that is received after being reflected on the road surface. And
The fading generation unit 12 generates such fading in a pseudo manner. The fading generation unit 12 also generates noise in consideration of the influence of the wiper differential and the like. The configuration is shown in FIG.

As shown in FIG. 2, the fading generator 1
Reference numeral 2 denotes a splitter 121 for splitting the input signal from the signal generator 11 into two, modulators 122 and 123 for quadrature-modulating the signal split by the splitter 121, and a modulator 12
2 that supplies a noise signal as a modulation signal to the noise generator 12
4, a Doppler generator 125 for generating a Doppler signal as a modulation signal in a modulator 123, and modulators 122 and 1
23 and a synthesizer 126 for synthesizing an output from the synthesizer 23.

An input signal from the signal generator is supplied to a distributor 12.
1 branches into two. One of the split signals is a modulator 1
At 22, the amplitude is modulated by the noise signal from the noise generator 124. The other of the split signals is a Doppler signal from Doppler generator 125, which is shifted to a Doppler frequency according to the vehicle speed.

Note that the modulator 122 adds independent noise signals to the in-phase component and the quadrature component to the branched signal. The modulator 123 creates a signal of “input signal + Doppler frequency” using a sine wave of a Doppler frequency corresponding to a preset vehicle speed.

The signals modulated by the modulators 122 and 125 are combined by the combiner 126 and output to the antenna 17 as an output signal.

Next, the operation of the on-board ETC device tester according to the present embodiment will be described with reference to FIGS.

First, the bit error measurement of the ETC on-board unit will be described. As shown in FIG. 3, the signal generator 11 includes a reference pattern generator 111 and a modulator 112. The signal generator 11 outputs the reference pattern generated by the reference pattern generator 111 to the modulator 112 and Output to the comparator 141 of the error measuring device.

The modulator 112 modulates a carrier having a predetermined frequency with a reference pattern and outputs the modulated carrier to the fading generator 12.

As described above, the fading generation section 12 adds fading to the input signal to
7 is output.

The signal radiated from the antenna 17 is ET
It is received by the antenna of the on-board C device 19 and demodulated by the on-board ETC device 19. The ETC in-vehicle device 19 outputs the demodulated signal to the bit error measuring unit 14 via the cable 20.

The bit error measuring section 14 includes a comparator 141
And the error counter 142, and compares the reference pattern from the reference pattern generator 111 with the demodulated signal, detects a mismatch, and outputs a detection signal. Error counter 14
2 counts the detection signal from the comparator 141. The count of the error counter 142 is performed for a reference pattern having a predetermined length.

The value counted by the error counter 142 is output to the arithmetic and control unit 15. Then, the arithmetic control unit 15 obtains a bit error rate by dividing the count value by the number of bits of the reference pattern, and displays the bit error rate on a display (not shown).

Next, measurement of the reception sensitivity will be described.
Also in this case, the bit error is measured in the same manner as the bit error measurement, and the bit error rate is displayed on the display. Then, the arithmetic and control unit 15 gradually lowers the transmission power level from the antenna 17, and executes a bit error measurement each time. When the measured bit error rate deteriorates to a predetermined value, the arithmetic and control unit 15 calculates the reception power of the on-board ETC device based on the transmission power level at that time and the coupling coefficient between the antennas in the shield case 18. Then, the receiving sensitivity is obtained.

Next, measurement of the transmission power of the on-board ETC device will be described. In this case, a signal is transmitted from the on-board ETC device 19. Then, the signal is received by the antenna 17, and the receiving unit 13 performs amplification, frequency conversion, demodulation, and the like of the received signal to convert the signal into a form that can be easily calculated.
The arithmetic control unit 15 calculates the transmission power based on the intensity of the received signal and the antenna coupling coefficient in the shield case 18.

As described above, E according to the present embodiment
The TC vehicle-mounted device tester measures a bit error, a reception sensitivity, and a transmission power.

As described above, according to the embodiment of the present invention, the ETC vehicle-mounted device is actually mounted on the vehicle without actually mounting the vehicle on the vehicle, and without actually driving the vehicle. A performance test can be performed by simulating a state in which the vehicle is running.

In this embodiment, only the test of the on-board ETC device has been described.

[0042]

According to the present invention, an on-board ETC device is actually mounted on a vehicle by using a tester that simulates fading caused by running of the vehicle, includes the fading in a transmission signal, and transmits the signal. Thus, a measurement result in a state close to that can be obtained without running the vehicle.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram illustrating details of a fading generation unit 12 of FIG. 1;

FIG. 3 is a block diagram showing details of a signal generator and a bit error measurement diagram for explaining the operation of the on-board ETC device of FIG. 1;

FIG. 4 is a block diagram for explaining a test method for a conventional ETC vehicle-mounted device.

FIG. 5 is a diagram for explaining a radio wave propagation path from a roadside device to an ETC vehicle device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Signal generation part 12 Fading generation part 13 Receiving part 14 Bit error measurement part 15 Operation control part 16 ETC in-vehicle equipment tester main body 17 Antenna 18 Shield case 19 ETC in-vehicle equipment 20 Cable 111 Reference pattern generation part 112 Modulator 121 Divider 122 Modulation Device 123 modulator 124 noise generator 125 Doppler generator 126 synthesizer 41 ETC on-board unit 42 power meter 43 frequency counter 44 bit error measuring device

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification symbol FI // G07B 15/00 510 H04L 13/00 315

Claims (5)

[Claims] 1. A signal generating means for generating a transmission signal receivable by an on-board ETC device for performing a performance test of an on-board ETC device mounted on a vehicle; It has fading generating means for generating fading and simulating a reception state of the on-board ETC device when the vehicle is traveling, and an antenna for transmitting a transmission signal in which fading has been generated by the fading generating means. ETC on-board equipment tester characterized by the following. 2. A shield case for housing the antenna and the ETC on-vehicle device therein to block external radio waves and prevent reflection of internal radio waves, and a shield case for demodulating a signal demodulated by the ETC on-vehicle device. 2. The ET according to claim 1, further comprising a cable to be taken out of the case.
C onboard equipment tester. 3. The antenna according to claim 1, wherein the antenna is a transmitting / receiving antenna, and the ET is determined based on a signal strength received by the transmitting / receiving antenna.
3. The ETC on-board unit tester according to claim 2, further comprising an arithmetic control unit for obtaining the transmission output of the on-board C unit. 4. The signal generating means has a reference pattern generating means for generating a reference pattern, is connected to the reference pattern generating means and the cable, and compares the reference pattern with the demodulated signal to generate a bit. 3. The in-vehicle ETC tester according to claim 2, further comprising a bit error measuring unit for measuring an error. 5. When measuring the bit error, the transmission signal power of the in-vehicle device tester is reduced stepwise, and the input level to the wireless device under measurement is calculated from the transmission power when the bit error rate is deteriorated to a predetermined value. The ETC on-vehicle device tester according to claim 4, wherein the receiving sensitivity is measured.