JP3075268B2 - Automatic toll collection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toll booth which collects tolls at existing or new places where tolls are generated due to traffic or parking of vehicles, such as highways, toll roads, parking lots, and gas stations. The present invention relates to an automatic toll collection system that automatically collects coins and bills without stopping a traveling vehicle or passing coins and bills between a driver and a collection member when passing or stopping.

[0002]

2. Description of the Related Art Conventionally, an automatic toll collection system using a radio wave described in Japanese Patent Application Laid-Open No. 8-287308 is known.

FIG. 15 shows an outline of an automatic toll collection system when a conventional automatic toll collection system is applied to a tollgate on a toll road. In FIG. 15, reference numeral 60 denotes a roadside machine installed on the tollgate lane, 61 denotes a vehicle passing through the tollgate, 6
Reference numeral 2 denotes an in-vehicle device that is a wireless device mounted on the vehicle 61;
Is a central processing unit connected to the roadside unit 60. In order to reduce interference due to interference between a plurality of roadside devices 60 installed on each lane of a tollgate, the transmission and reception frequencies of radio waves used by the roadside devices 60 of each lane are different from each other in the adjacent lanes. A frequency, for example, two types of frequencies are set. Therefore, since the frequency used by the roadside device 60 is set in advance, in the communication between the roadside device 60 and the vehicle-mounted device 62, the vehicle-mounted device 62 entering the toll lane is used by the roadside device 60 in the lane. Frequency to be selected instantaneously and wireless communication is performed.

The operation of the prior art with the above configuration will be described below. The in-vehicle device 62 mounted on the vehicle 61 that has entered the tollgate decodes the response request signal continuously transmitted by the roadside device 60 and uses the response request signal written in the response request signal by the roadside device 60. Get the frequency channel data for The in-vehicle device 62 uses this data to determine the transmission / reception frequency used by the roadside device 60 on the traffic lane to be entered from now on, and performs two-way wireless communication with the roadside device to automatically collect tolls. It is done regularly.

More specifically, information such as a driver's bank account is acquired from the vehicle-mounted device 62 via the roadside device 60, and a toll is deducted from the account, or an IC card of a predetermined format is obtained. By holding the monetary information and adding a function of reading and writing the information of the IC card to the vehicle-mounted device 62, a predetermined amount of money can be stored from the IC card according to the fee information sent from the roadside device 60 to the vehicle-mounted device 62. Is possible by electronic payment procedures that reduce

In the case of a mileage-dependent toll road, the roadside machine 60 sends the entry information to the vehicle-mounted machine 62 at the entrance-side tollgate and stores it.
By receiving the entrance information from, the mileage and route are determined, and the toll is settled electronically.

[0007]

A feature of the wireless communication method between the roadside device and the vehicle-mounted device is that the roadside device performs wireless communication only with the vehicle-mounted device moving within a limited spatial range. In the case of the automatic toll collection system, the communication area is approximately 3 × 4 m, and the transmission and reception beams of the roadside machine antenna installed 4 to 5 m above the road surface are formed into a desired shape. Further, as another feature, the base station continuously transmits a response request signal repeatedly at fixed time intervals, for example, at intervals of several milliseconds to several tens of milliseconds, and the in-vehicle device mounted on the vehicle enters the communication area. When this response request signal is received and a predetermined response signal is transmitted to the roadside device, a series of two-way communication is started. The roadside device has a plurality of frequency channels having different transmission and reception frequencies.

However, depending on the installation condition of the roadside device antenna and the traffic of another large vehicle, the transmission radio wave from another roadside device may temporarily exceed the receiving sensitivity of the onboard device. The response request signal is demodulated to obtain different frequency channel data, and as a result, a frequency different from the transmission / reception frequency used by the roadside unit at the tollgate to which the on-board unit is to enter is selected, and normal communication can be performed. May disappear. In order to prevent this, it is conceivable to add another circuit configuration to detect the reception level, but since the on-board unit is a radio unit mounted on the vehicle, it is required to be small and lightweight, and the transmission and reception frequency of this roadside unit is selected. It is necessary to make the circuit configuration to be as small as possible.

According to the present invention, after entering a limited communication area generated by a roadside device antenna, a response request signal transmitted by the roadside device is received and demodulated in a short time to obtain frequency channel data, and a reception demodulation of the onboard device is performed. A circuit configuration for detecting the control voltage of the AGC amplifier mounted in the unit is provided, and the reception power level is also detected without adding a new circuit configuration for detecting the reception power level of the response request signal from the roadside unit. The object of the present invention is to realize a small in-vehicle device having improved accuracy in selecting a transmission / reception frequency and an automatic toll collection system using the same.

[0010]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides an AGC (auto gain control) amplifier, which is an essential circuit configuration for securing a receiving dynamic range of an on-vehicle device, in which the control voltage is increased. Focusing on the fact that it depends on the reception power level in the LNA, the reception demodulation unit of the on-vehicle device has an LNA connected to the antenna means, a first BPF connected to the LNA, and a mixer connected to the first BPF. A second BPF connected to the mixer, an AGC amplifier connected to the second BPF, a detection circuit connected to the AGC amplifier, a demodulation unit connected to the detection circuit and the on-vehicle device CPU unit, An AGC control voltage generator connected to the circuit and having its output connected to the AGC amplifier; and an AD for converting the output of the AGC control voltage generator into a digital signal and outputting it to the onboard unit CPU.
By providing a converter and a local signal generator connected to the mixer, the reception power level can be estimated from the reception demodulation unit.

Thus, the on-vehicle device sets the frequency of the local signal generator in accordance with the first transmission / reception frequency among a plurality of transmission / reception frequencies which can be used by the roadside device known in advance, for example, two types of transmission / reception frequencies. And the output value of the AGC control voltage generator when the frequency of the local signal generator is set in accordance with the second transmission / reception frequency. By comparing the two digital values, it is possible to judge the higher received power level, together with the frequency channel data of the roadside device obtained from the demodulated signal, and the transmission and reception used by the roadside device on the traffic lane to enter from now on The frequency can be selected with high accuracy. That is, a small vehicle-mounted device can be realized without adding a circuit configuration for newly detecting the reception power level of the response request signal from the roadside device to the vehicle-mounted device.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to an entrance tollgate and an exit tollgate at a place where a toll is generated due to the passage of a vehicle or parking, or a plurality of tollgates at one of the tollgates. An automatic toll collection system that automatically receives a toll using a roadside device installed for each lane and an in-vehicle device mounted on a vehicle that bidirectionally communicates necessary information with the roadside device by radio. Machine, an antenna means for transmitting and receiving a radio signal to and from the roadside machine, a transmission modulation unit for sending a transmission signal to the antenna means, a reception demodulation unit for demodulating a reception signal from the antenna means, the transmission modulation unit The in-vehicle device CPU unit connected to the reception demodulation unit, and an information input / output unit connected to the in-vehicle device CPU unit for inputting / outputting information for electronically performing fee collection, the reception demodulation unit includes: Said Connected LNA to the antenna means
(Low noise amplifier) and the first LNA connected to the LNA.
(BPF) and the first BPF
, A second BPF connected to the mixer, an AGC (auto gain control) amplifier connected to the second BPF, a detection circuit connected to the AGC amplifier, A demodulation unit connected to a circuit and outputting a demodulated signal to the on-vehicle unit CPU unit; an AGC control voltage generation unit connected to the detection circuit and outputting its output to the AGC amplifier; and an output of the AGC control voltage generation unit And a local signal generator connected to the mixer, wherein the on-vehicle device C
An automatic toll collection system in which a PU unit is provided with output data comparison means for comparing digital data output from the AD converter and frequency selection means for selecting a transmission / reception frequency. By converting the AGC control voltage value for controlling the gain of the AGC amplifier into a digital value and comparing the voltage levels, it is possible to enhance the accuracy of selecting the transmission / reception frequency of the roadside unit, and to increase the reception level without adding a new circuit configuration. This has the effect that a small in-vehicle device with improved frequency selection accuracy as well as detection can be realized.

According to a second aspect of the present invention, the reception demodulation unit comprises:
An LNA connected to antenna means, a first BPF connected to the LNA, a mixer connected to the first BPF, a second BPF connected to the mixer, and a second BPF AGC amplifier connected to the
A detection circuit connected to the C amplifier; a demodulation unit connected to the detection circuit for outputting a demodulated signal to the CPU unit; and an AGC control voltage connected to the detection circuit and output to the AGC amplifier A generator, an AD converter for digitally converting an output of the AGC control voltage generator,
A second AD converter connected to the detection circuit for digitally converting the output of the detection circuit; and a local signal generator connected to the mixer. The output of the AD converter is provided to the on-vehicle device CPU unit. 2. An output data comparing means for comparing a plurality of digital data, in which an output of the second AD converter is assigned to a lower bit group, to the upper bit group, and a frequency selecting means for selecting a transmission / reception frequency. Automatic toll collection system, even if the difference between the AGC control voltage values cannot be detected, it becomes possible to select the transmission / reception frequency of the roadside unit by comparing the output of the detection circuit.
When the outputs of the two A / D converters are connected to the output data comparison means, it is possible to compare the data of both A / D converters in a single operation by assigning digital values to the upper bit group and the lower bit group, respectively. The in-vehicle device CPU unit has the effect that both data can be compared with a short number of steps, and a small in-vehicle device capable of selecting a transmission / reception frequency with high accuracy in a short time can be realized.

According to a third aspect of the present invention, there is provided a roadside provided for each of a plurality of traffic lanes at both an entrance tollgate and an exit tollgate, or at one of the tollgates, at a place where a toll is generated due to the passage or parking of a vehicle. Machine, and an automatic toll collection system that automatically collects tolls using an in-vehicle device mounted on a vehicle that bidirectionally communicates necessary information with the roadside device by wireless, wherein the onboard device is Antenna means for transmitting and receiving a radio signal, a transmission modulation unit for transmitting a transmission signal to the antenna means, a reception demodulation unit for demodulating a reception signal from the antenna means, and connected to the transmission modulation unit and the reception demodulation unit On-vehicle device CPU, and on-vehicle device CPU
An information input / output unit connected to the unit for inputting / outputting information for electronically receiving a charge, wherein a reception demodulation unit includes an LNA connected to the antenna unit, and a first input / output unit connected to the LNA. A BPF, a mixer connected to the first BPF, a second BPF connected to the mixer, an AGC amplifier connected to the second BPF, and a detection circuit connected to the AGC amplifier. A demodulation unit connected to the detection circuit and outputting a demodulated signal to the on-vehicle device CPU unit; an AGC control voltage generation unit connected to the detection circuit and outputting the output to the AGC amplifier; Unit output and the output of the detection circuit are connected to the on-vehicle device CP.
A switch that is controlled by the control of the U unit, an AD converter that is connected to the switch and converts the output of the switch into a digital signal, a latch that is connected to the AD converter and holds data by a signal of the vehicle-mounted device CPU unit, A local signal generator connected to a mixer, wherein the latch includes a lower byte latch for inputting output data of the AD converter, and an upper byte latch for inputting output data of the lower byte latch, Onboard unit CPU
An automatic toll collection system provided with output data comparison means for comparing the output data of the lower byte latch and the upper byte latch, and frequency selection means for selecting a transmission / reception frequency, even when a difference between AGC control voltage values cannot be detected. The comparison of the output of the detection circuit can be realized by one AD converter, and the AGC control voltage and the output value of the detection circuit are aligned to the upper bit group and the lower bit group by the latch, and the on-board unit CP
It is possible to output to the U section, and the in-vehicle unit CPU unit can compare the data of both AD converters in one operation, realizing a small in-vehicle unit that selects the transmission / reception frequency with high accuracy in a short time Has the effect of being able to.

According to a fourth aspect of the present invention, there is provided a roadside installed for each of a plurality of traffic lanes at both an entrance tollgate and an exit tollgate or at one of the tollgates at a place where a toll is generated due to vehicle traffic or parking. Machine, and an automatic toll collection system that automatically collects tolls using an in-vehicle device mounted on a vehicle that bidirectionally communicates necessary information with the roadside device by wireless, wherein the onboard device is Antenna means for transmitting and receiving a radio signal, a transmission modulation unit for transmitting a transmission signal to the antenna means, a reception demodulation unit for demodulating a reception signal from the antenna means, and connected to the transmission modulation unit and the reception demodulation unit A receiving and demodulating unit comprising: an LNA connected to the antenna means; a first BPF connected to the LNA; and a first BPF connected to the LNA.
, A second BPF connected to the mixer, an AGC amplifier connected to the second BPF, a detection circuit connected to the AGC amplifier, and a demodulation connected to the detection circuit A demodulation unit that outputs a signal to the on-vehicle unit CPU unit; an AGC control voltage generation unit that is connected to the detection circuit and has an output connected to the AGC amplifier; and an AD that converts the output of the AGC control voltage generation unit to digital.
A converter, a ROM for inputting an output value of the AD converter to an address and converting the data into preset data, and a local signal generator connected to the mixer. An automatic toll collection system provided with output data comparison means for comparing output data of a ROM and frequency selection means for selecting a transmission / reception frequency, wherein a relationship between a voltage output by an AGC control voltage generator and a gain of an AGC amplifier is determined. Even in the case of having non-linear characteristics, the output data comparison means of the on-vehicle unit CPU unit depends on the gain of the AGC amplifier by using the output of the AD converter for the address input of the ROM in which the data considering the non-linear characteristics is written in advance. Values, that is, values that are linearly related to the received power level, can be transmitted and received by roadside equipment without adding a new circuit configuration. It allows you to select a frequency with high precision, has the effect of small-sized vehicle-mounted device can be realized.

According to a fifth aspect of the present invention, the ROM includes a bus driver whose output is controlled by a vehicle unit CPU unit, and a data setting unit connected to a higher-order bit group of the bus driver input is provided. 5. The automatic toll collection system according to claim 4, wherein the output of the AD converter is connected to the lower bit group of the bus driver input, and the output of the AD converter having fixed data preset in the data setting unit in the upper bit group is provided. The output data comparison means of the on-vehicle unit CPU can be captured at a time, and can be directly used as the address value of the data conversion table when converting the A / D converter output data into desired data in the on-vehicle unit CPU Thus, the software processing can be performed with a short number of steps, and an effect that a high-speed frequency selection operation can be realized with a small in-vehicle device.

According to a sixth aspect of the present invention, the antenna means includes an on-vehicle device antenna for transmitting and receiving a radio signal to and from the roadside device;
A signal separator connected to the on-vehicle device antenna,
The transmission modulator according to claim 1, wherein the transmission modulator transmits a transmission signal to the on-vehicle device antenna via the signal separator, and the reception demodulator demodulates a reception signal from the on-vehicle device antenna via the signal separator. The automatic toll collection system according to any one of the above, which has an effect of realizing an in-vehicle device with a simple configuration and improved communication reliability.

According to a seventh aspect of the present invention, the antenna means has a vehicle-mounted device transmitting antenna for transmitting a radio signal to the roadside device and a vehicle-mounted device receiving antenna for receiving a radio signal from the roadside device. The automatic toll collection system according to any one of claims 1 to 5, wherein a unit is connected to the on-vehicle unit transmission antenna to transmit a transmission signal, and a reception demodulation unit is connected to the on-vehicle unit reception antenna to demodulate a reception signal. And
This has the effect that the in-vehicle device antenna can secure transmission / reception isolation and can realize the in-vehicle device with improved communication reliability.

[0019] The invention described in claim 8 is a roadside installed at each of a plurality of traffic lanes at both an entrance tollgate and an exit tollgate or at one of the tollgates at a place where tolls are generated due to vehicle traffic or parking. Machine, and an automatic toll collection system that automatically collects tolls using a vehicle-mounted device mounted on a vehicle that bidirectionally communicates necessary information with the roadside device by radio, wherein the reception demodulation unit of the roadside device has An automatic toll collection system having the same configuration as the reception and demodulation unit of the on-vehicle device according to any one of Items 1 to 7, wherein the transmission / reception frequency used by the on-vehicle device in which the roadside device moves in the communication area with a small configuration It has the effect that it can be detected.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a schematic diagram when the vicinity of a tollgate is viewed from above when the automatic toll collection system is applied to a tollgate on a toll road. In FIG. 1, reference numeral 1 denotes a roadside device, which exchanges information relating to a toll collection procedure with a vehicle-mounted device 4 mounted on a vehicle 3 moving in a communication area 2 having a vehicle width direction of about 3 m and a traveling direction of about 4 m. , Using two-way radio, at a height of several meters above each lane,
For example, it is installed using a gantry 5. Reference numeral 6 denotes a central processing unit that is connected to the roadside device 1 and performs a procedure for collecting tolls accompanying the traveling of the vehicle 3 based on information obtained through two-way communication with the vehicle-mounted device 4. Reference numeral 7 denotes a notice antenna device for performing bidirectional communication with the vehicle-mounted device 4 moving in the notice antenna communication area 8.

FIG. 2 is a schematic configuration diagram of the vehicle-mounted device 4. In FIG. 2, reference numeral 10 denotes an on-vehicle device antenna, 11 denotes a signal separator composed of a switch and a circulator connected to the on-vehicle device antenna, and 12 denotes a transmission modulation unit for transmitting a transmission signal to the on-vehicle device antenna 10. 13 is an in-vehicle device antenna 10
Is a reception demodulation unit for demodulating a reception signal from the roadside device 1 received by the in-vehicle device, 14 is a vehicle unit CPU unit connected to the transmission modulation unit 12 and the reception demodulation unit 13, and 141 is in the vehicle unit CPU unit 14 and receives An output data comparing means 142 for comparing digital data relating to a reception level output from the demodulation section 13, a frequency 142 for selecting a transmission / reception frequency of the roadside device from a result of the output data comparison means and a demodulated signal output from the reception demodulation section 13 The output data comparison means 141 and the frequency selection means 142 are selection means, and are realized by software processing in the on-vehicle equipment CPU unit 14. Reference numeral 15 denotes an IC card reader / writer.
C card 16 can be inserted and removed, and IC
When the card 16 is inserted, the in-vehicle device CPU unit 14 and the IC card 16 are electrically connected, and information in the IC card 16 is read according to an instruction from the in-vehicle device CPU unit 14,
Or rewrite.

FIG. 3 is a configuration diagram showing the configuration of the reception demodulation unit 13 in detail. In FIG. 3, reference numeral 20 denotes the signal separator 11.
Amplifies the signal received by the on-vehicle device antenna 10 to a predetermined level by the LNA connected to the LNA. Reference numeral 21 denotes a first BPF, which is constituted by a band-pass filter that removes a signal outside a predetermined frequency band, and passes at least a first transmission / reception frequency and a second transmission / reception frequency band of the roadside device 1. Reference numeral 22 denotes a mixer for down-converting the frequency band of the received signal output from the LNA 20 to a predetermined frequency band according to the signal of the local signal generator 27.

Reference numeral 23 denotes a second BPF for removing signals outside a predetermined frequency band, and reference numeral 24 denotes a so-called automatic gain control amplifier for changing a gain in accordance with an AGC control voltage output from an AGC voltage generator 28. is there. Reference numeral 25 denotes a detection circuit, and reference numeral 26 denotes a demodulation unit that demodulates an output of the detection circuit by a modulation method used for a transmission signal of the roadside device 1. 29 is an output of the AGC control voltage generator 28,
This is an AD converter for digitally converting the C control voltage. AD
The output of the converter 29 is input to the output data comparison means 141 in the on-vehicle equipment CPU section 14, and the output of the demodulation section 26 is input to the frequency selection means 142. In addition, the roadside machine 1 also
This is a wireless device having a transmission modulation unit and a reception demodulation unit as in the case of the on-vehicle device 4, and has a configuration generally shown in FIGS. However, the roadside device 1 is not provided with a card reader / writer for exchanging information with an IC card or a credit card used as an electronic wallet for paying a toll electronically.

An embodiment of the above configuration will be described below. The vehicle 3 that has entered the notice antenna communication area 8 first performs two-way communication between the notice antenna device 7 and the vehicle-mounted device 4 mounted on the vehicle 3. That is, the in-vehicle device 4 acquires transmission data from the notice antenna device 7 via the in-vehicle device antenna 10, the signal separator 11, the reception / demodulation unit 13, and the in-vehicle device CPU unit 14, and conversely, the in-vehicle device CPU unit 1
4. The information from the vehicle-mounted device 4 is transmitted to the notice antenna device 7 via the transmission modulation unit 12, the signal separator 11, and the vehicle-mounted device antenna 10.

The main functions of the notice antenna device 7 for performing wireless communication with the on-vehicle device 4 are as follows: the operation of the on-vehicle device 4 is started by a response request signal of the notice antenna device 7; And a notification that automatic toll collection is possible to the driver of the vehicle 3 by displaying an image, text, or voice through a display or a speaker connected to the vehicle-mounted device 4.

Generally, a tollgate is composed of a plurality of traffic lanes, but a driver who drives the vehicle 3 is informed by an instruction from the notice antenna device 7 that automatic toll collection is possible.
The vehicle 3 is moved to a predetermined traffic lane, in the case of FIG.
From one of the traffic lanes D.

Next, while the vehicle 3 travels in any one of the traffic lane A to the traffic lane D shown in FIG. 1, the vehicle-mounted device 4 performs two-way wireless communication with the roadside device 1 in the communication area 2. Do. The communication area 2 is formed by shaping the beam shape of the transmission / reception antenna of the roadside unit 1 so as to have a strength that satisfies a reception power higher than a level receivable by the onboard unit 4 in an area approximately 3 m in the vehicle width direction and about 4 m in the traveling direction. Irradiate the radio waves.

In order to shape the transmission / reception beam shape by the antenna of the roadside device 1 so that it can communicate with the vehicle-mounted device 4 moving within the limited communication area 2, a high-performance antenna is required, and the shape of the antenna is large. Become Also, in addition to the effects of fixed obstacles such as surrounding walls and roofs, the roadside machine 1 is also affected by dynamic obstacles such as large vehicles running on adjacent lanes.
The transmission and reception beams interfere with each other in a complicated manner, and there are factors such as the transmission beam of the other roadside device 1 obstructing the communication between the roadside device 1 and the on-vehicle device 4 in the communication area 2. Therefore, the roadside device 1 of the automatic toll collection system uses two types of preset frequencies as transmission and reception frequencies. For example, the traffic lane A and traffic lane C of FIG. 1 use the first frequency f1, and the traffic lanes B and D use the second frequency f2.

FIG. 4 is a schematic diagram of a signal form of the wireless communication method used by the roadside device 1 and the on-vehicle device 4 to automatically collect a fee. In FIG. 4, reference numeral 30 denotes a slot, which is composed of a serial digital data string of several hundred bits per slot. The communication between the roadside device 1 and the onboard device 4 is as follows:
A frame 34 is composed of a plurality of slots 30, and predetermined information is exchanged by repeatedly transmitting and receiving the frame 34.

The first slot is an FCM (frame control message) slot 31 including a response request signal transmitted from the roadside device 1, and the last slot is an ACK (ack) slot 3 including a response signal transmitted from the vehicle-mounted device 4.
3 and the remaining slots are the roadside unit 1 and the onboard unit 4
An MDC (message data channel) slot 32 containing bidirectional communication data with the MDC. The FCM slot 31 contains frequency channel data composed of several bits, which is information on the transmission / reception frequency used by the roadside device 1. The ACK slot 33 may be changed to the MDC slot 32 depending on the situation.

For example, if each slot is composed of 800 bits, the frame 34 is composed of four slots 30, and the transmission rate of one bit is 1 Mbps, the frame 34 has a time configuration of about 3.2 milliseconds. . When the interval between the frames 34 is 0 second, the response request signal is emitted to the communication area 2 at 3.2 millisecond intervals. The communication method between the notice antenna device 7 and the on-vehicle device 4 is almost the same except that the number of slots 30 constituting the frame 34 and the bit configuration constituting each slot 30 are different.

The contents of communication between the roadside device 1 and the vehicle-mounted device 4 at the exit-side tollgate are as follows. First, the vehicle-mounted device 4 transmits to the roadside device 1 entrance information indicating a tollgate where the vehicle 3 has entered the toll road. The roadside device 1 calculates the travel distance and the travel amount of the vehicle 3 from the acquired entrance information, and transmits the calculated travel distance and the travel price to the vehicle-mounted device 4. The in-vehicle device 4 that has received the travel fee information debits the amount corresponding to the travel fee from the IC card 16 by the in-vehicle device CPU unit 14 and the IC card reader / writer 15, thereby completing the toll collection process. The entrance information is acquired and stored from the roadside device 1 when the vehicle-mounted device 4 moves to the tollgate on the entrance side. In addition, on a toll road with a uniform toll, it is only necessary to collect a predetermined toll at one location on the entrance side or the exit side.

As described above, the roadside device 1 uses a plurality of transmission / reception frequencies, for example, two types of transmission / reception frequencies in order to reduce interference due to interference. The in-vehicle device 4 moving in the communication area 2 does not know in advance the transmission / reception frequency used by the roadside device 1 forming the communication area 2. Therefore, when the vehicle-mounted device 4 enters the communication area 2, it is necessary to determine the transmission / reception frequency used by the roadside device 1 in a short time.

The two transmission / reception frequencies used by the roadside device 1 are denoted by f1 and f2. First, the on-board unit 4 is the roadside unit 1
The setting corresponding to the transmission / reception frequency f1 is performed. For example, if the intermediate frequency output from the mixer 22 is f3, the local signal generator 27 is set to have the frequency of (f1−f3) or the frequency of (f1 + f3). The roadside device 1 transmits the response request signal F
The CM slot 31 is continuously transmitted. The response request signal received by the on-vehicle device antenna 10 passes through the signal separator 11 and is amplified by the LNA 20 to a predetermined voltage.
Is down-converted to a signal in the intermediate frequency f3 band, and f
3 is converted to a second BPF 23
After being amplified by the AGC amplifier 24 through the
5 is detected. When the transmission / reception frequency of the roadside unit 1 is f1, the received signal output from the detection circuit 25 is demodulated by the demodulation unit 26 and output to the onboard unit CPU unit 14. In-vehicle device CP
The U unit 14 obtains the frequency channel data of the roadside device 1 from the demodulated signal of the FCM slot 31. Note that f1 and f2
If the frequency difference with the second BPF unit 23 is Δf,
By setting the center frequency of the pass frequency band to f3 and having a characteristic of not passing a frequency band of ± Δf with respect to f3, the passage of the frequency band of an adjacent channel can be restricted. Therefore, when the transmission / reception frequency of the roadside device 1 is f2, demodulation cannot be performed by the demodulation unit 26 and frequency channel data cannot be obtained.

The AGC control voltage generator 28 changes the AGC control voltage to A according to the magnitude of the signal detected by the detection circuit 25.
Output to the GC amplifier 24. As a result, it becomes possible to input a received signal having a signal level that can be demodulated sufficiently accurately by the demodulation unit 26 to the detection circuit 25 and the demodulation unit 26. That is, when the level of the received signal received by the on-vehicle device antenna 10 is low, the gain of the AGC amplifier 24 is increased. Conversely, when the level of the received signal received by the on-vehicle device antenna 10 is high, the gain of the AGC amplifier 24 is increased. By outputting a low control voltage, the dynamic range of the receiving circuit can be expanded as a result, and a highly accurate receiving system can be configured.

The in-vehicle device CPU unit 14 has an FCM slot 31
Is detected, the A / D converter 29 outputs an A / D conversion timing signal for digital conversion, obtains the AGC control voltage value from the digitally converted output of the AGC control voltage generator 28, and stores it in the output data comparison means 141. That is, if the transmission / reception frequency of the roadside device 1 is f1, the AGC
The amplifier 24 has a gain set in accordance with the received power level, and the AGC control voltage value at that time is set to the on-board unit CPU unit 1.
4 is acquired. If the transmission / reception frequency of the roadside device 1 is not f1, the reception signal is A due to the characteristics of the second BPF unit 2.
Not input to the GC amplifier 24, for example, the AGC amplifier 24
Is set to the maximum gain, and the on-vehicle device CPU unit 14 acquires the AGC control voltage value at that time.

After a certain time has elapsed, the onboard unit CPU unit 1
4 sets the local signal generator 27 according to the transmission / reception frequency f2 of the roadside device 1. By setting the time,
The on-vehicle device 4 sets the local signal generator 27 to (f2-
The frequency is set to be f3) or (f2 + f3). Then, the in-vehicle device CPU unit 14
By the same processing as described above, the frequency channel data used by the roadside device 1 and the AG
Obtain the C control voltage value. Note that a certain time is a period during which the FCM slot 31 can be received at least once, and a period of at least the frame 34 + 1 slot 30 is required.

Next, the transmission / reception frequency selection operation in the vehicle-mounted unit CPU unit 14 will be described. The frequency selecting means 142 of the on-vehicle device CPU unit 14 selects a transmission / reception frequency of the roadside device 1 from the stored frequency channel data obtained from the FCM slot 31. In the communication area 2, the in-vehicle device 4 cannot demodulate the transmitted radio waves from the adjacent roadside device 1 due to the lower directional sensitivity of the roadside device antenna than the receiving sensitivity of the in-vehicle device 4 due to the directional characteristics of the roadside device antenna. Accordingly, the stored frequency channel data is either f1 or f2, and the frequency selecting means 142 selects a transmission / reception frequency according to the stored frequency channel data.

However, in addition to the effects of fixed obstacles such as surrounding walls and roofs, the transmitting and receiving beams of the plurality of roadside units 1 are complicatedly interfered by dynamic obstacles such as large vehicles running on adjacent lanes. In some cases, frequency channel data of f1 and f2 is temporarily obtained. In this case, the frequency selection unit 142 selects the transmission / reception frequency by comparing the two AGC control voltage values obtained by the output data comparison unit 141. Specifically, when the set gain of the AGC amplifier 24 is low, the local signal generator 2
By detecting the set frequency of 7, the transmission / reception frequency used by the roadside device 1 can be estimated. When the transmission / reception frequency of the roadside device 1 is selected, the on-vehicle device CPU unit 14 sets the local signal generator 27 according to this frequency, and obtains information necessary for the toll procedure between the roadside device 1 and the on-vehicle device 4. Performs two-way communication.

As described above, the output of the AGC control voltage generator 28 for controlling the gain of the AGC amplifier 24 can be converted into a digital signal and taken into the on-vehicle unit CPU section 14. The circuit configuration for detecting the reception level is a demodulation circuit. Apart from this, it is possible to realize a small in-vehicle device with improved reception frequency detection and frequency selection accuracy without providing a new one, and an automatic toll collection system using the same. Although one mixer 22 for down-conversion to the intermediate frequency band is shown, a reception system for down-conversion by a plurality of mixers 22 may be used. Further, a configuration in which the mixer 22 is included in the AGC control loop may be used. Also, the in-vehicle device 4 is located in the communication area 2.
Although not shown, it can be determined whether a general carrier sense circuit is provided in the on-vehicle device 4.

Although the receiving / demodulating section 13 in FIG. 3 is described assuming digital amplitude modulation / demodulation, it may have a configuration as shown in FIG. 5 according to the modulation / demodulation method.

(Embodiment 2) FIG. 6 is a schematic configuration diagram of the reception demodulation unit 13 of the vehicle-mounted device 4 in this embodiment. In FIG. 6, reference numeral 40 denotes a second AD converter connected to the detection circuit 25. When the outputs of the AD converter 29 and the second AD converter 40 are connected to the data bus of the in-vehicle device CPU unit 14, A
In this configuration, the output of the D converter 29 is connected to the upper bit group of the bus of the in-vehicle device CPU unit 14, and the output of the second AD converter 40 is connected to the lower bit group. Figure 3 shows other configurations and functions
This is the same as the reception demodulation unit 13 shown in FIG.

The structures of the automatic toll collection system and the vehicle-mounted device are the same as those shown in FIGS.

The present embodiment will be described below with the above configuration. When the vehicle 3 on which the on-vehicle device 4 is mounted moves to the communication area 2, the on-vehicle device C is transmitted by the method described in the first embodiment.
The PU unit 14 acquires the AGC control voltage values output from the two types of AGC control voltage generation units 28, and also acquires and stores the output level of the detection circuit 25 at that time.

When the vehicle 3 enters the communication area 2, that is, at the end of the communication area 2 distant from the roadside device 1, the received signal level at the vehicle-mounted device 4 is expected to be extremely small. Therefore,
Two A obtained by switching the local signal generator 27
Both the GC control voltage values may be the voltage values that operate the AGC amplifier 24 at the maximum gain, and the AGC control voltage values are almost the same.

The output data comparing means 141 of the on-vehicle device CPU unit 14 determines whether there is no difference between the two outputs of the AD converter 29.
The output of the second AD converter 40 is compared. This value, that is, the one with the higher reception level is estimated as the transmission / reception frequency used by the roadside device 1. Then, the on-vehicle device CPU unit 14 sets the local signal generator 27 according to the frequency, and performs bidirectional communication of information necessary for the toll procedure between the roadside device 1 and the on-vehicle device 4.

The roadside device 1 and the on-vehicle device 4 move between the vehicle 3 and the communication region 2 which is an extremely limited region.
Necessary information needs to be bidirectionally communicated,
The software processing in the section 14 needs to be performed as fast as possible. The connection between the AD converter 29, the second AD converter 40, and the data bus of the in-vehicle device CPU unit 14 is performed by connecting the output of the A / D converter 29 to the upper bit group of the bus of the in-vehicle device CPU unit 14, Since the output of the converter 40 is connected to the lower-order bit group, the output data comparison means 141 of the on-vehicle device CPU unit 14 can store the AD converter 29 and the second AD conversion in one register or memory in one input operation. The output of the device 40 can be stored.

For example, the quantization accuracy of the AD converter 29 and the second AD converter 40 is set to 8 bits, and the on-board unit CPU
If the data bus of the unit 14 has a 16-bit configuration, the output of the A / D converter 29 is connected to the upper byte and the output of the second A / D converter 40 is connected to the lower byte. The in-vehicle device CPU unit 14 can capture and handle the output of the converter 40 as data synthesized into a 16-bit configuration. In the data comparison, it is sufficient to simply subtract the 16-bit data, and the output data comparison means 141 of the vehicle-mounted device CPU unit 14 can compare the two data with a short number of steps. The toll collection procedure and the processing method in the frequency selection means 142 are performed in the manner described in detail in (Embodiment 1).

As described above, the output data comparing means 141 of the on-vehicle unit CPU section 14 can compare both data with a short number of steps, and a circuit configuration for detecting the reception level is newly provided separately from the demodulation circuit. It is possible to realize a small in-vehicle device capable of detecting a reception level without providing a circuit configuration and having improved frequency selection accuracy, and an automatic toll collection system using the same.

(Embodiment 3) FIG. 7 is a schematic configuration diagram of the reception demodulation unit 13 of the vehicle-mounted device 4 in the present embodiment. 7, reference numeral 41 denotes an AGC control voltage generator 28 and a detection circuit 25.
A switch for switching the respective outputs according to an instruction from the on-vehicle device CPU unit 14 and outputting the outputs to the AD converter 29;
Is a latch connected to the AD converter 29. Other configurations and functions are the same as those of the reception demodulation unit 13 shown in FIG.

The structures of the automatic toll collection system and the vehicle-mounted device are the same as those shown in FIGS.

FIG. 8 is a diagram showing the connection configuration of the switch 41, the AD converter 29 and the latch 42 in more detail. As one embodiment, the quantization accuracy of the AD converter 29 is 8 bits, Fourteen buses are shown in a 16-bit configuration. The latch 42 is separated into an upper byte latch 43 and a lower byte latch 44.
The output of the bit is connected to the input of the lower byte latch 44, and the output of the lower byte latch 44 is
3 is connected to the lower byte of the bus of the in-vehicle device CPU unit 14. The output of the upper byte latch 43 is
It is connected to the upper byte of the bus of the in-vehicle device CPU unit 14.

The present embodiment will be described below with the above configuration. When the vehicle 3 equipped with the on-vehicle device 4 moves to the communication area 2, the on-vehicle device CPU unit 14 estimates the transmission / reception frequency of the roadside device 1 in the same manner as the method described in (Embodiment 2). Then, bidirectional communication of information necessary for the toll procedure is performed between the roadside device 1 and the vehicle-mounted device 4.

When the in-vehicle device 4 moves to the communication area 2, the in-vehicle device CPU unit 14 sends the local signal generator 27 to the roadside device 1
Is set in accordance with the transmission / reception frequency f1. Next, the in-vehicle device CPU unit 14 controls the latch enable signal of the latch 42 so that the latch function operates. Specifically, for example, the digital signal “Hi”
gh ”level or“ Low ”level.

Next, a switch control signal is output so that the switch 41 outputs an AGC control voltage which is an output of the AGC control voltage generator 28. Specifically, for example, it outputs a “High” level or a “Low” level of a digital signal according to the characteristics of the switch 41.

Next, the on-vehicle device CPU unit 14
9 outputs an AD conversion timing signal for digitally converting the input data. Specifically, the signal is a signal corresponding to the characteristics of the AD converter 29, and outputs, for example, a pulse signal. The AD converter 29 starts the conversion at the falling edge of the pulse signal, for example, and ends the digital conversion after a specified conversion time. The pulse rises after this conversion time. This AD conversion timing signal is input to the latch clocks of the upper byte latch 43 and the lower byte latch 44 of the latch 42, and latches the input at the rising edge, for example. Therefore, the lower byte latch 44 latches the AGC control voltage data, which is the output of the AD converter 29, to the output in synchronization with the rise.

Next, the on-vehicle unit CPU unit 14 switches the switch control signal and outputs the output of the detection circuit 25 to the AD converter 29.
, And outputs an AD conversion timing signal again to digitally convert the output of the detection circuit. In synchronization with the falling edge of the second latch, the upper byte latch 43
Is the AGC control voltage data output from the lower byte latch 44, and the lower byte latch 44
Is output from the detection circuit.

Next, the on-vehicle unit CPU unit 14 reads the output of the latch 42 and stores it in a register or memory, and controls the latch enable signal. For example, the latch 42 is electrically disconnected from the bus of the in-vehicle device CPU unit 14 by setting the latch output to a high impedance state. In-vehicle device CPU unit 1
In the processing of the output data comparing means 141 in step 4, the output of the AD converter 29 and the output of the detection circuit 25 can be captured and handled at once as data synthesized into a 16-bit configuration. Just subtract. That is, the in-vehicle device CPU unit 14 can compare both data with a short number of steps. The toll collection procedure and the processing method in the frequency selection means 142 are performed in the manner described in detail in (Embodiment 1).

As described above, the in-vehicle unit CPU unit 14 can compare the two data with a short number of steps, and the circuit configuration for detecting the reception level can be received without providing a new circuit configuration separately from the demodulation circuit. It is possible to realize a small in-vehicle device that enables level detection and has improved frequency selection accuracy and an automatic toll collection system using the same.

(Embodiment 4) FIG. 9 is a schematic configuration diagram of the reception demodulation unit 13 of the vehicle-mounted device 4 according to the present embodiment. In FIG. 9, reference numeral 45 denotes a ROM composed of a read-only memory connected to the AD converter 29 and the on-vehicle device CPU unit 14;
The address of the OM 45 is connected to the output of the AD converter 29, and the data output of the ROM 45 is connected to the vehicle unit CPU unit 14. Other configurations and functions are the same as those of the reception demodulation unit 13 shown in FIG.

As an application example of the automatic toll collection roadside system, when applied to a tollgate on a toll road, a schematic diagram when the vicinity of the tollgate is viewed from above is similar to FIG.
The configuration of the vehicle-mounted device used for this is the same as in FIG.

The present embodiment having the above configuration will be described below. A when input at AGC amplifier 24 is fixed
The relationship between the AGC control voltage output from the GC control voltage generator 28 and the output level generally shows nonlinearity. For example, as shown in FIG. 10, although the output level of the AGC amplifier 24 increases as the AGC control voltage increases,
The amplification factor becomes smaller, for example, as shown in FIG.
As the GC control voltage approaches 3V, the output level of the AGC amplifier shows a saturation tendency. That is, the relationship between the AGC control voltage value and the output level is not a linear relationship.

The two-way communication with the roadside device 1 after the in-vehicle device 4 enters the communication area 2 and the method of selecting the transmission / reception frequency of the roadside device 1 are carried out, for example, by the method described in (Embodiment 1). The relationship between the input and output of the AD converter 29 is generally linear, and the AGC control voltage generator 2
The output of 8 is linearly digitally converted. The digitized output of the AGC control voltage generator 28 is input to the address of the ROM 45. The ROM 45 outputs data stored in advance according to the address value.

The ROM 45 stores the AGC control voltage and AG
Data that complements the nonlinear relationship of the C amplifier 24 is stored in advance. For example, as shown in FIG.
The output level of No. 4 is divided by ΔV at a fixed interval, and new data is made to correspond to an AGC control voltage in a range corresponding to this value as an address value. For example, when the output level is divided into eight as shown in FIG. 11, if the range of the AGC control voltage is A, the digital value of the AGC control voltage,
Is assigned a binary number data of "000" to the address input value of "3". Similarly, when the range of the AGC control voltage is B, “001” is sequentially allocated. When the range of the AGC control voltage is C, “010” is allocated. When the range of the AGC control voltage is H, “111” is allocated. The digital value of the AGC control voltage, which is the output of
The OM 45 converts the data into data having a linear relationship with the output level of the AGC amplifier 24 and outputs the data to the on-vehicle device CPU unit 14.

The vehicle unit CPU unit 14 that has obtained this data
In the processing of the output data comparing means 141, the output of the AGC amplifier 24 having the non-linear characteristic is converted by the ROM 45, so that a linear value can be obtained for the received power level, and more advanced comparison processing can be performed. The toll collection procedure and the processing method in the frequency selection means 142 are performed in the manner described in detail in (Embodiment 1).

As described above, the in-vehicle unit CPU section 14 can compare the two data with high accuracy, and the circuit configuration for detecting the reception level can be changed without providing a new circuit configuration separately from the demodulation circuit. It is possible to realize a small in-vehicle device capable of detecting and improving frequency selection accuracy and an automatic toll collection system using the same.

(Embodiment 5) FIG. 12 is a schematic configuration diagram of the reception demodulation unit 13 of the vehicle-mounted device 4 in the present embodiment. FIG.
In 2, a bus driver 47 is connected to the AD converter 29 and the data setting unit 46. The lower bit group of the bus driver 47 is connected to the output of the AD converter 28 and the upper bit group is connected to the data setting unit 46. I have. Other configurations and functions are the same as those of the reception demodulation unit 13 shown in FIG.

The configurations of the automatic toll collection system and the vehicle-mounted device are the same as those shown in FIGS. 1 and 2, respectively.

The digital data output from the AGC control voltage generator 28, which is the output from the AD converter 29, reflects the nonlinear characteristics of the AGC amplifier 24, as described in detail in the fourth embodiment. is there. The output data comparing means 141 uses the acquired output value of the AGC control voltage generator 28 to convert data in a software manner based on the non-linear characteristic. Specifically, the relationship between the input and output characteristics shown in FIG. 11 is held in advance as a data table, and conversion is performed by referring to this table according to the output value of the AGC control voltage generator 28.

FIG. 13 is a diagram showing the connection structure of the AD converter 29, the data setting section 46, and the bus driver 47 in more detail. As one embodiment, the quantization accuracy of the AD converter 29 is 8 bits, and The data bus of the CPU 14
It is shown in a 6-bit configuration. The bus driver 47 includes an upper byte bus driver 48 and a lower byte bus driver 49
The 8-bit output of the AD converter 29 is connected to the input of the lower byte bus driver 49, and the output of the data setting unit 46 is connected to the upper byte bus driver 48. The data setting unit 46 individually sets the digital state of each bit to “High” or “Lo”.
For example, it is composed of eight switches that can be set to "w".

The present embodiment having the above configuration will be described below. First, when the in-vehicle device 4 moves to the communication area 2, the in-vehicle device CPU unit 14 outputs a bus driver enable signal of the bus driver 47, and captures the AGC control voltage value in the in-vehicle device CPU unit 14. The output is electrically connected to the bus of the vehicle unit CPU unit 14. Specifically, for example, it outputs a “High” level or a “Low” level of a digital signal according to the characteristics of the bus driver 47.

Next, the on-vehicle device CPU unit 14
An A / D conversion timing signal for converting the input data into digital data is output to the bus 9, and the digitally converted data is read via the bus driver 47. Next, the in-vehicle device CPU unit 14 converts the data based on the data by referring to a data table stored in the memory in advance.
The capacity of the data table depends on the quantization precision of the AD converter 29. For example, in the case of 8 bits, it is sufficient to previously store 256 types of converted data.

This data conversion table is sequentially arranged in the memory space from “00000000” to “11111111” in accordance with the output data of the AD converter 29. The upper byte address value of this memory space is set in the data setting unit 4
By setting in step 6, the 16-bit data obtained from the bus driver 47 can be used as it is as a memory space designation address for referencing the data table in the processing by the output data comparison means 141 of the on-vehicle device CPU unit 14. It becomes possible. For example, the data table is expressed in hexadecimal,
The switches from “0xA000H” to “0xA0FFH” are arranged, and the switches of the data setting unit 46 are grounded to the power supply voltage indicating digital “High” and the ground indicating digital “Low” as shown in FIG. By doing so, the upper byte of the output value of the bus driver 47 is fixed to “0x0AH” in hexadecimal. The toll collection procedure and the processing method in the frequency selection means 142 are performed in the manner described in detail in (Embodiment 1).

As described above, the in-vehicle device CPU section 14 can convert data with a very short number of steps using the output of the bus driver 47, and a new circuit configuration for detecting the reception level is provided separately from the demodulation circuit. A small in-vehicle device that enables reception level detection without increasing a circuit configuration and improves frequency selection accuracy, and an automatic toll collection system using the same can be realized.

(Embodiment 6) FIG. 14 is a schematic configuration diagram of an in-vehicle device 4 according to the present embodiment. In FIG. 14, 35
Is an on-board unit receiving antenna, 36 is an on-board unit transmitting antenna, 1
Reference numeral 2 denotes a transmission modulation unit for transmitting a transmission signal to the on-vehicle device transmission antenna 36, reference numeral 13 denotes a reception demodulation unit for demodulating a reception signal received from the roadside device 1 received by the on-vehicle device reception antenna 35, and reference numeral 14 denotes a transmission modulation unit 12. In-vehicle device CP connected to reception demodulation unit 13
U unit 141 is an output data comparison unit that compares digital data related to the reception level, which is an output of the reception demodulation unit 13, in the onboard unit CPU unit 14, and 142 is the result of the output data comparison unit and the output of the reception demodulation unit 13. Frequency selecting means for selecting the transmission / reception frequency of the roadside unit from the demodulated signal which is the output data comparing means 141 and the frequency selecting means 142
Is realized by software processing in the vehicle unit CPU unit 14. Reference numeral 15 denotes an IC card reader / writer, and an IC card 16
When the IC card 16 is inserted, the in-vehicle device CPU unit 14 and the IC card 16 are electrically connected, and according to an instruction from the in-vehicle device CPU unit 14,
The information in the IC card 16 is read or rewritten.

The present embodiment will be described below with the above configuration. In-vehicle device antenna is replaced with in-vehicle device reception antenna 3
5. By separating the antenna into the on-vehicle transmitter antenna 36, transmission and reception isolation can be ensured, and the transmission beam shape and the reception beam shape can be individually formed.
Communication reliability between the vehicle-mounted device 4 and the roadside device 1 can be improved. The toll collection procedure and the processing method in the frequency selection means 142 are performed in the manner described in detail in (Embodiment 1).

As described above, the communication reliability between the vehicle-mounted device 4 and the roadside device 1 can be improved, and the circuit configuration for detecting the reception level can be improved without providing a new circuit configuration separately from the demodulation circuit. It is possible to realize a small in-vehicle device capable of detecting and improving frequency selection accuracy and an automatic toll collection system using the same.

(Embodiment 7) The above (Embodiment 1)
By using the configuration of the reception demodulation unit 13 described in (1) to (Embodiment 6) for the reception demodulation unit of the roadside device 1, a small and high-speed frequency selection operation having a configuration for selecting the transmission frequency of the vehicle-mounted device 4 Can be realized.

[0079]

As described above, according to the present invention, the output value of the AGC control voltage generator when the frequency of the local signal generator is set to the first transmission / reception frequency usable by the roadside unit and the second transmission / reception The output value of the AGC control voltage generator when the frequency of the local signal generator is set to the frequency
The U unit obtains and compares the two digital values to select the transmission / reception frequency used by the roadside device on the traffic lane to be entered from now on, and newly selects the reception power of the response request signal from the roadside device. An advantageous effect is obtained that it is possible to realize a small in-vehicle device capable of detecting a reception level without adding a circuit configuration for detecting a level and improving the frequency selection accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an automatic toll collection system near a tollgate according to an embodiment of the present invention when viewed from above.

FIG. 2 is a schematic configuration diagram of a vehicle-mounted device according to an embodiment of the present invention;

FIG. 3 is a schematic configuration diagram of a reception demodulation unit of the on-vehicle device according to one embodiment of the present invention;

FIG. 4 is a diagram showing a communication format between a roadside device and a vehicle-mounted device according to an embodiment of the present invention;

FIG. 5 is a schematic configuration diagram of a reception demodulation unit of the vehicle-mounted device according to one embodiment of the present invention;

FIG. 6 is a schematic configuration diagram of a reception demodulation unit of the vehicle-mounted device according to one embodiment of the present invention;

FIG. 7 is a schematic configuration diagram of a reception demodulation unit of the on-vehicle device according to one embodiment of the present invention;

FIG. 8 is a diagram showing a connection state of a switch, an AD converter, and a latch according to an embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of a reception demodulation unit of the vehicle-mounted device according to one embodiment of the present invention;

FIG. 10 is a schematic diagram showing characteristics of an AGC amplifier according to an embodiment of the present invention.

FIG. 11 is a schematic diagram showing a relationship between characteristics of the AGC amplifier according to the embodiment of the present invention and ROM data stored in advance.

FIG. 12 is a schematic configuration diagram of a reception demodulation unit of the on-vehicle device according to one embodiment of the present invention;

FIG. 13 is a diagram showing a connection configuration of an AD converter, a data setting unit, and a bus driver according to an embodiment of the present invention;

FIG. 14 is a schematic configuration diagram of a vehicle-mounted device according to an embodiment of the present invention;

FIG. 15 is a schematic diagram of a conventional automatic toll collection system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roadside apparatus 2 Communication area 3 Vehicle 4 Onboard equipment 5 Gantry 6 Central processing unit 7 Notice antenna apparatus 8 Notice antenna communication area 10 Onboard equipment antenna 11 Signal separator 12 Transmission modulation unit 13 Reception demodulation unit 14 Onboard equipment CPU unit 15 IC card Reader / writer 16 IC card 20 LNA 21 First BPF unit 22 Mixer 23 Second BPF 24 AGC amplifier 25 Detection circuit 26 Demodulation unit 27 Local signal generator 27 28 AGC voltage generation unit 29 AD converter 30 Slot 31 FCM slot 32 MDC slot 33 ACK slot 34 Frame 35 In-vehicle unit reception antenna 36 In-vehicle unit transmission antenna 40 Second AD converter 41 Switch 42 Latch 43 Upper byte latch 44 Lower byte latch 45 ROM 46 Data setting unit 47 Bus driver 8 high byte bus driver 49 low byte bus driver 60 roadside device 61 vehicle 62 vehicle-mounted device 141 outputs the data comparison unit 142 frequency selecting means

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-36087 (JP, A) JP-A-6-44488 (JP, A) JP-A-7-95119 (JP, A) JP-A-5-95119 314393 (JP, A) JP-A-7-325996 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G07B 15/00 510 G06F 17/60 G06K 17/00 G08G 1/017

Claims (8)

(57) [Claims] 1. A roadside machine installed at both an entrance tollgate and an exit tollgate or a plurality of traffic lanes at one of the tollgates at a place where a toll is generated due to the passage or parking of a vehicle, and In an automatic toll collection system that automatically collects tolls using a vehicle-mounted device mounted on a vehicle that bidirectionally communicates necessary information by wireless, the vehicle-mounted device includes:
Antenna means for transmitting and receiving a radio signal to and from the roadside device, a transmission modulation unit for transmitting a transmission signal to the antenna means, a reception demodulation unit for demodulating a reception signal from the antenna means, the transmission modulation unit and the reception demodulation An on-vehicle unit CPU unit connected to the unit, and an information input / output unit connected to the on-vehicle unit CPU unit for inputting / outputting information for electronically performing toll collection; LNA (low noise amplifier) connected to the LNA, a first BPF (bandpass filter) connected to the LNA, a mixer connected to the first BPF, and a second BPF connected to the mixer And A connected to the second BPF.
A GC (auto gain control) amplifier and the AG
A detection circuit connected to the C amplifier; a demodulation unit connected to the detection circuit for outputting a demodulated signal to the CPU unit; and an AGC control voltage connected to the detection circuit and output to the AGC amplifier A generator, an AD converter for digitally converting an output of the AGC control voltage generator,
A local signal generator connected to the mixer,
An automatic toll collection system in which the on-vehicle device CPU unit includes an output data comparison unit for comparing digital data output from the AD converter and a frequency selection unit for selecting a transmission / reception frequency. 2. A reception demodulation unit comprising: an LNA connected to antenna means; a first BPF connected to the LNA;
A mixer connected to the first BPF, a second BPF connected to the mixer, an AGC amplifier connected to the second BPF, a detection circuit connected to the AGC amplifier, A demodulation unit connected to a circuit and outputting a demodulated signal to the on-vehicle unit CPU unit; an AGC control voltage generation unit connected to the detection circuit and outputting its output to the AGC amplifier; and an output of the AGC control voltage generation unit An AD converter for digitally converting the signal; a second AD converter connected to the detection circuit for digitally converting an output of the detection circuit;
A local signal generator connected to the mixer;
Output data comparing means for comparing a plurality of digital data in which the output of the AD converter is assigned to a high-order bit group and the output of the second AD converter is assigned to a low-order bit group; 2. The automatic toll collection system according to claim 1, further comprising a frequency selection unit for selecting a frequency. 3. A roadside machine installed for each of a plurality of traffic lanes at both an entrance tollgate and an exit tollgate or a tollgate at a place where a toll is generated due to the passage or parking of a vehicle, and In an automatic toll collection system that automatically collects tolls using a vehicle-mounted device mounted on a vehicle that bidirectionally communicates necessary information by wireless, the vehicle-mounted device includes:
Antenna means for transmitting and receiving a radio signal to and from the roadside device, a transmission modulation unit for transmitting a transmission signal to the antenna means, a reception demodulation unit for demodulating a reception signal from the antenna means, the transmission modulation unit and the reception demodulation A vehicle unit CPU unit connected to the unit, and an information input / output unit connected to the vehicle unit CPU unit for inputting / outputting information for electronically performing toll collection. A connected LNA, a first BPF connected to the LNA, a mixer connected to the first BPF, a second BPF connected to the mixer, and a connected to the second BPF An AGC amplifier, a detection circuit connected to the AGC amplifier, a demodulation unit connected to the detection circuit and outputting a demodulated signal to the on-vehicle device CPU unit, and an output connected to the detection circuit and connected to the AG. An AGC control voltage generator connected to an amplifier, a switch for switching the output of the AGC control voltage generator and the output of the detection circuit under the control of the on-vehicle CPU, and an output of the switch connected to the switch for digital output. An A / D converter for conversion; a latch connected to the A / D converter and holding data according to a signal from the on-vehicle device CPU unit; and a local signal generator connected to the mixer. A lower byte latch for inputting the output data of the converter; and an upper byte latch for inputting the output data of the lower byte latch. The in-vehicle device CPU unit compares the output data of the lower byte latch and the output data of the upper byte latch. An automatic toll collection system provided with output data comparison means for performing the operation and frequency selection means for selecting the transmission and reception frequencies. 4. A roadside machine installed at each of a plurality of traffic lanes at both an entrance tollgate and an exit tollgate at a place where a toll is generated due to vehicle traffic or parking, and one of the tollgates, In an automatic toll collection system that automatically collects tolls using a vehicle-mounted device mounted on a vehicle that bidirectionally communicates necessary information by wireless, the vehicle-mounted device includes:
Antenna means for transmitting and receiving a radio signal to and from the roadside device, a transmission modulation unit for transmitting a transmission signal to the antenna means, a reception demodulation unit for demodulating a reception signal from the antenna means, the transmission modulation unit and the reception demodulation And a receiving and demodulating unit connected to the antenna unit, a first BPF connected to the LNA, and a first BPF connected to the LNA. A mixer, a second BPF connected to the mixer,
An AGC amplifier connected to the BPF, a detection circuit connected to the AGC amplifier, a demodulation unit connected to the detection circuit and outputting a demodulated signal to the onboard unit CPU unit, and an output connected to the detection circuit An AGC control voltage generator connected to the AGC amplifier, an A / D converter for digitally converting an output of the AGC control voltage generator,
A ROM for inputting an output value of the converter to an address and converting the data into preset data; and a local signal generator connected to the mixer, wherein the on-vehicle unit CPU compares the output data of the ROM. Output data comparing means,
An automatic toll collection system provided with frequency selection means for selecting a transmission / reception frequency. 5. A ROM comprising a bus driver whose output is controlled by a vehicle unit CPU unit, and a data setting unit connected to an upper bit group of the bus driver input;
5. The automatic toll collection system according to claim 4, wherein an output of an AD converter is connected to a lower bit group of the bus driver input. 6. An antenna unit having an on-vehicle device antenna for transmitting and receiving a radio signal to and from a roadside device, and a signal separator connected to the on-vehicle device antenna, wherein a transmission modulator is configured to transmit the radio signal via the signal separator. 6. The automatic toll collection system according to claim 1, wherein a transmission signal is transmitted to an on-vehicle device antenna, and a reception demodulation unit demodulates a reception signal from the on-vehicle device antenna via the signal separator. 7. An on-vehicle device transmitting antenna for transmitting a radio signal to a roadside device, and an on-vehicle device receiving antenna for receiving a radio signal from the roadside device. Is connected to and sends a transmission signal,
The automatic toll collection system according to any one of claims 1 to 5, wherein a reception demodulation unit is connected to the on-vehicle device reception antenna to demodulate a reception signal. 8. A roadside machine installed for each of a plurality of traffic lanes at both an entrance tollgate and an exit tollgate or a tollgate at a place where a toll is generated due to vehicle traffic or parking, and 8. An automatic toll collection system that automatically collects a toll using an on-vehicle unit mounted on a vehicle that bidirectionally communicates necessary information by wireless, wherein the reception demodulation unit of the roadside unit includes: An automatic toll collection system having the same configuration as the receiving and demodulating unit of the on-vehicle device described in (1).