JPH06181449A - Mobile object identifying device - Google Patents

Abstract

PURPOSE:To provide the mobile object identifying device in which no crosstalk takes place even when plural responders are in existence in a communication area. CONSTITUTION:For the communication among an interrogator 4 and responders 8-1,... n-channels of time division channels are set, channel information representing the presence of an idle channel is added to data to be sent and the interrogator 4 sends the result and each of the responders 8-1,..., 8-n receiving the channel information selects an optional channel of idle channels and returns data to be returned to which an ID code of its own is added. The responder 4 discriminates the returned data as to whether or not an error such as collision is in existence for each channel and when no error is in existence, an occupied right of the channel is given to a relevant responder. When any error is in existence, channel information of a channel is kept idle in a succeeding cycle for the transmission and the responder receiving it confirms the idle channel, an optional idle channel is selected and sent again while the ID code is added to the data to be returned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving body identifying device used in an automatic toll collection system or the like at a tollgate on a toll road.

[0002]

2. Description of the Related Art As a conventional moving body identifying apparatus, there has been one that transmits and receives data between a transponder mounted on a moving body such as an automobile and a transponder fixed at a toll booth. In this type of mobile identification device, the communication between the interrogator and the responder is
It used a one-to-one connection method.

[0003]

Since the above-mentioned conventional mobile unit identification apparatus has a 1: 1 connection system between the interrogator and the transponder, interference occurs when a plurality of transponders exist within the communication area of the interrogator. , Communication is not working properly. In order to prevent this interference, it is better to narrow the communication area, but in the automatic charge collection system at the tollgate, if the communication area is narrowed, there is a problem that high-speed vehicles cannot be supported.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a mobile body identifying apparatus which does not cause interference even if a plurality of responders exist in a communication area.

[0005]

The moving body identifying apparatus of the present invention comprises an interrogator fixed to a moving body path and a responder provided in each moving body. A predetermined number of time-division channels are set for inter-device communication, and the interrogator is provided with means for transmitting channel information indicating whether or not there is an empty allocation for each channel to the data to be transmitted to the responder. The responder comprises means for selecting any one of the empty channels of the transmitted channel information, attaching a self-unique ID code to the return data, and returning the data.
And the interrogator, means for determining the presence or absence of a transmission error in the channel used for the return, and means for granting the exclusive right to the responder that returned the data using the channel when there is no transmission error, When there is a transmission error, it is provided with means for adding null information to the channel and causing the transmitting means to retransmit the channel information in the next cycle. If the device is not yet given the channel occupancy right, it is provided with means for changing to an arbitrary channel which is still empty and for returning the return data and the self-specific ID code from the return means,
Until the responder is given the right to occupy any channel, the interrogator transmits the empty channel information and the responder repeats the response to select any empty channel.

In this mobile object identifying apparatus, transmission data and channel information are transmitted from the interrogator to the responder using one time-divided channel. This channel information indicates whether or not the exclusive right is assigned to each channel number, and “empty” or the “ID code” of the transponder that has acquired the exclusive right is entered for each channel number. The transponder receiving the transmission data from the interrogator returns the return data together with its own unique ID code using an arbitrary "empty" channel. The interrogator determines whether or not there is a transmission error such as a collision in the returned data from the responder returned for each channel,
If there is no transmission error, the responder is given the exclusive right to the channel, and thereafter, communication with the responder is performed using this channel. Then, in the channel information to be transmitted after the next cycle, the "empty" of the channel No. is changed to the "ID code" of the responder to which the exclusive right is given. In the interrogator, if there is a collision between responders in a certain channel, the channel number of the channel information of the next cycle is "empty".
Send as it is. The responder receives the "empty" channel information, knows that there is a collision on its selected channel, and this time changes to an arbitrary "empty" channel and returns the returned data and its own ID again. Return the code. As long as there is a collision in the interrogator, the "empty" of the time division channel information of the channel with the collision is not changed. The channel is changed to "empty" and the return data and the self ID code are repeated.

[0007]

The present invention will be described in more detail with reference to the following examples. FIG. 1 is a diagram showing a concept of a state in which the mobile body identification device of the present invention is used in a toll road automatic charge collection system. In FIG. 1, a toll booth 2 is installed in each lane 1, and an interrogator 4 and a camera 5 for influencing illegal vehicles are installed on a stanchion 3 on each lane 1, respectively. A vehicle sensor 6 is provided on the roadside near the toll booth 2. A traveling vehicle (moving body) 7 is provided with a responder 8 for communicating with the interrogator 4.

FIG. 2 is a block diagram showing the configuration of the interrogator 4, which includes an oscillator 11, a modulator 12, and a power amplifier 13.
, Circulator 14, transmitting / receiving antenna 15, mixer 16, filter 17, amplifier 18, demodulator 1
9 and a CPU 20. The 2.45 GHz band signal oscillated by the oscillator 11 is transmitted to the CPU 20 by the modulator 12.
After being ASK-modulated by and amplified by the power amplifier 13, it passes through the circulator 14 and is emitted from the antenna 15.

The reflected wave from the transponder 8 is received by the antenna 15, passes through the circulator 14, and then the mixer 16
After being homodyne detected with the output of the oscillator 11, the signal is passed through the filter 17, amplified by the amplifier 18, demodulated by the demodulator 19, and processed by the CPU 20. When the vehicle running on the lane 1 approaches the tollgate and enters the communication area of the interrogator 4, data is exchanged between the interrogator 4 and the responder 8. Here, the interrogator 4 can communicate with n responders in a time division manner, and employs a time division multiple access method with a plurality of responders 8. Therefore, the vehicle identification device for each lane adopted here is the interrogator 4 as shown in FIG.
, And n transponders 8 _-1 , 8 _-2 , ..., 8- _n . However, the numerical value of n can be changed as described later.

Next, the connection operation of this mobile unit identification apparatus will be described with reference to the line control example shown in FIG. One cycle is time-divided into a plurality of slots (channels), SL ₀ is used as a channel from the interrogator 4 to each responder, and SL ₁ , ..., SL _n
Are assigned to the channels to each responder 8 _-1 , 8 _-2 , ..., 8 _-n . Therefore, even if there are n vehicles in the communication area of the interrogator 4, communication is possible without interference.

At the time of SL ₀ transmission, the interrogator 4 indicates, in addition to the information to be transmitted to the transponder, the channel number assigned to the transponders 8 _-1 , ..., 8- _n and the presence or absence of "empty" in each channel. Send with the code shown. Responder 8 that received SL _0
-i selects any one of the empty channels and sends it back to the interrogator 4. In this case, the data to be returned is sent with its own unique ID. The interrogator 4 monitors the error of the data returned from each responder, and if there is an error (when a transmission error occurs or when there is a collision of transmission from the responder), the following It informs the transponder of the channel number in error on channel SL ₀ of the cycle. In order to notify an error, for example, by resending “empty” status of each channel as “empty”, the responder receiving this will still send the channel even though it is the channel returned by itself. Is “empty”,
By confirming the "empty", the responder knows that an error such as a collision has occurred in its own return. Responder 8 _-i , which has learned this, again randomly selects a certain one from the “empty” channels and retransmits it to interrogator 4.

The interrogator 4 makes an error in the returned channel.
If there is no channel,
Give the exclusive right. After that, between the responder and the interrogator 4
The transponder occupies that channel until
It has and communicates with the interrogator 4. Then this channel
Access control will be described with reference to a specific example shown in FIG. Figure 5
Is n = 2 and there are two vehicles in the communication area of the interrogator 4.
It shows the case. Channel C of the first cycle
H₀Then, from the interrogator 4 to the responder 8_-1, 8_-2Sent to
Channel information is CH₁: Sky, CH₂: Empty (time point
t₁). Responder 8 that received this channel information_-1, 8_-2
Channel CH₁Use your own ID code
Is the ID₁, ID₂If you send back (at time t₂), O
Answer device 8_-1, 8_-2The return of will collide. In this case, the interrogator 4
Is the transponder 8_-1, 8_-2Without giving the exclusive right to any of the
Channel CH of the cycle₀And channel information C
H₁: Sky, CH ₂: Send empty (time t₃). this
Responder 8 received_-1, 8_-2Is the channel information CH₁Visit
Shine. Channel CH₁Remains empty so the previous rhinoceros
It was judged that the data in the clew did not reach the interrogator 4, and
Randomly select one of the empty channels and send
It The result is transponder 8_-2Is the channel CH₁Sent by
(Time t_Four), Responder 8_-1Is the channel CH₂Returned by
(Time point t_Five). This time, the data received by the interrogator 4
Since there is no data collision, the interrogator 4_-2Channel
Le CH₁Give the exclusive right of the responder 8_-1To channel CH₂
Grant the exclusive right of. And channel information CH₁: ID
₂, CH₂: ID₁Is sent (at time t₆). Accept this
Trusted responder 8_-1, 8_-2Then, in the channel information, I
Since D is set, the connection with the interrogator 4 is completed normally.
Communication after occupying the given channel.
I do.

In the mobile unit identification apparatus of this embodiment, even if a plurality of transponders are present in the communication area, communication is possible without interference. Considering the toll booth, even if a plurality of motorcycles enter the communication area at the same time, the communication can be normally performed, and it is not necessary to provide a booth dedicated to the motorcycle. Further, since the communication area can be set wide, it does not pass through the communication area before the communication is normally completed, and it is possible to cope with a vehicle passing at a high speed.

In the apparatus of this embodiment, the number of channels n may be set appropriately. For example, the traffic amount measured by using the vehicle sensor 6 or the like, or the central apparatus sends it to the tollgate. The number of channels may be variably set according to the traffic volume. In this way, since the number of channels is changed according to the communication traffic, efficient communication can be performed without waste.

A flat antenna is used as the antenna used in the interrogator 4 in the apparatus of the above embodiment, and the communication distance is limited to several tens of meters as shown in the characteristic A of FIG. I can't take it big. Therefore, as the transmitting / receiving antenna of the interrogator, as shown in FIG.
(Leakage fixed axis cable) If the antenna 20 is installed along the runway 21, the communication range can be made larger as shown by the characteristic B in the figure, and by using the time division multiple access system together,
A uniform communication area can be secured for the length of the LCX, and the communication area can be greatly expanded. Therefore, uniform communication quality can be obtained in a wide communication area, and a large amount of data can be transmitted and received. Further, since the communication area can be set wide, communication is possible even for a moving body that passes at high speed.

On the other hand, if the communication area is widened, a plurality of transponders will exist in the communication area. However, by using the time division multiple access method as the connection method between the interrogator and the transponder, a plurality of transponders can be provided without interference. Communication is possible at the same time as the transponder. Next, a case where there are a plurality of lanes on the toll road and a plurality of interrogators are installed will be described. In this case, since the interrogators use the same frequency and are installed close to each other, interference such as a beat occurs and communication cannot be performed. Since the interrogator and the transponder were performing one-to-one communication, if a plurality of transponders exist in the communication area, there will be interference and communication will not be performed normally. As a result, there is a problem that the communication area must be narrowed and sufficient communication data cannot be transmitted / received to / from a moving body moving at high speed.

Therefore, in order to solve this problem,
Number of interrogators transmit at different frequencies
Frequency division, and between the interrogator and multiple transponders
Perform time division multiple access. The apparatus of this embodiment will be described with reference to FIG.
Will be explained. In Figure 1, there are two lanes
Two interrogators 4 are also installed. 1 on the right lane_A,
Left lane 1 _BAnd each lane 1_A1_BInstalled in
Interrogator 4_AFour_BAnd

The frequencies of the interrogators 4 _A and 4 _B are respectively f
_{If A} and f _B are used and the frequency interval is set to be sufficiently wider than the subcarrier frequency when the return data from the transponder is the baseband, the modulation frequency and the subcarrier frequency are set to be sufficiently wide to prevent mutual interference. The generated beat can be cut by the reception filter of the interrogator, and normal communication can be performed. The configuration of each interrogator 4 _A , 4 _B is the same as that shown in FIG. 2, and the frequencies used are different from each other.

Therefore, even if the interrogators are installed close to each other, the respective frequencies are f _A and f _B.
The filter 17 can be eliminated by making the frequency interval sufficiently wider than the modulation frequency or the subcarrier frequency. According to the apparatus of this embodiment, even if a plurality of interrogators are installed at close positions, interference such as beats does not occur between the interrogators. Further, even when there are a plurality of transponders in the communication area, normal communication can be performed without interference. In addition, the communication area can be set wider.

[0020]

According to the present invention, since the communication (connection) between the interrogator and the responder is the time division multiple access system, even when a plurality of responders are present in the communication area, there is no interference and normal operation is possible. Can communicate. Since there is no fear of interference in the communication area, there is an effect that the communication area can be set wide and normal communication can be performed even in a high-speed vehicle.

[Brief description of drawings]

FIG. 1 is a diagram showing a concept of a state in which a mobile body identification device of the present invention is used in a toll road automatic toll collection system.

FIG. 2 is a block diagram showing a configuration of an interrogator of the moving object identifying apparatus according to the embodiment.

FIG. 3 is a block diagram showing a schematic configuration of a moving body identifying apparatus according to the embodiment.

FIG. 4 is a diagram showing a general line control example for explaining the connecting operation of the interrogator and the responder of the mobile unit identification apparatus of the same embodiment.

FIG. 5 is a diagram for explaining a specific example of the connecting operation between the interrogator and the responder of the moving object identifying apparatus according to the embodiment.

FIG. 6 is a diagram for explaining a communication area by a plane antenna used in the moving body identification apparatus according to the embodiment.

FIG. 7 is a diagram illustrating a communication area by an LCX antenna used in the mobile unit identification apparatus according to the embodiment.

[Explanation of symbols]

4 Interrogator 8 _-1 , ..., 8- _n transponder

Claims (4)

[Claims] 1. A mobile body identification device comprising an interrogator fixed to a moving path and a responder provided to each mobile body, wherein a predetermined number of time division channels are provided for communication between the interrogator and the responder. The interrogator is provided with means for transmitting channel information indicating whether or not there is an empty allocation for each channel to the data to be transmitted to the responder, and each responder has empty channel information transmitted. Means for selecting any one of the channels, attaching a self-unique ID code to the return data and returning the data, and means for determining to the interrogator whether there is a transmission error in the channel used for the return If there is no transmission error, a means for granting the exclusive right to the responder that has returned data using that channel, and if there is a transmission error, add null information to that channel and send it to the next cycle. Channel information by means of With means to retransmit,
By the channel information retransmitted to each responder,
If your own device has not been given the right to own the channel,
An empty channel from the interrogator is provided until the responder is given the right to occupy the arbitrary channel, by providing a means for changing the channel to an arbitrary channel that is still empty and returning the return data and the self-specific ID code from the returning means. A mobile body identification device characterized in that a transmission of information and a response to an arbitrary empty channel selection from a responder are repeated. 2. The mobile unit identifying apparatus according to claim 1, further comprising means for measuring the amount of communication traffic, wherein the number of set channels of the time division channel is changed according to the amount of communication traffic. 3. The moving body identifying apparatus according to claim 1, wherein the transmitting means of the interrogator includes an LCX antenna provided along a moving direction. 4. The moving body identifying apparatus according to claim 1, wherein a plurality of the interrogators are provided and the transmission frequencies of the transmitting means for the respective interrogators are set to different values.