JP2677484B2 - Communication method of mobile identification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reads the identification number of a transponder from an interrogator using a non-contact communication means such as radio waves, or transmits data to the transponder held in a moving body. The present invention relates to a communication system in a mobile body identification device for writing, for example, a system that manages operation by identifying a mobile body that moves at high speed such as a train, or a car that passes a toll road by identifying a car. It is used in a system for managing information and other FA fields and logistics fields.

[0002]

2. Description of the Related Art FIG. 4 shows a schematic structure of a conventional moving body identifying apparatus. The interrogator 1 transmits the interrogation signal Q to the responder 2 by using non-contact communication means such as radio waves. Transponder 2
Receives this inquiry signal Q and returns a response signal A including its own identification number. The interrogator 1 reads the identification number of the transponder 2 by receiving the response signal A. In addition, the data included in the inquiry signal Q
Data is written from the interrogator 1 to the responder 2.

In this type of wireless communication system, data may not be normally received in one communication due to the influence of multipath, interfering waves, interference waves, and the like, and data error and Methods to prevent false alarms and increase system reliability are often used.

FIG. 5 shows a communication format when the data of the responder 2 is read twice from the interrogator 1. In this communication format, one frame consisting of several bytes is returned as a response to one command. FIG. 5A shows the signal format of the inquiry signal Q,
FIG. 5B shows the signal format of the response signal A. In FIG. 5A, COM1 is a command indicating the content of the question, and BCC is a check code for detecting an error in data transmission. In FIG. 5 (b), CO
M1 is a command indicating the content of the response (the same as the content of the question), ID1 is the identification number of the responder 2, DT
Reference numeral 1 indicates data read from the responder 2, and BCC indicates a check code for detecting a transmission error.

By using such a moving body identifying apparatus, a transponder 2 is mounted on a train and communicates with an interrogator 1 installed at a predetermined position along a track to identify the train, thereby operating the train. A system for managing or a system for mounting a transponder 2 on a car and communicating with an interrogator 1 installed near a tollgate to identify a car and manage a car passing through a toll road (for example, JP-A-3-1897
No. 92), etc. have been proposed.

[0006]

However, in the communication method in the conventional mobile unit identification apparatus, as shown in FIG. 5, one command corresponds to one frame of reply data, so that the communication is not performed. In order to improve reliability, even when it is desired to read the data of the same content continuously several times, the command must be transmitted every time, resulting in a time loss. Also, even if a command that returns several frames in succession to one command is added, the receiving side cannot accurately determine the beginning of one frame that is sent back in succession, so The received data cannot be decoded and the processing indicated by the reply data cannot be performed. Therefore, conventionally, as shown in the communication format of FIG. 5, it is necessary to transmit a command each time data of the same content is continuously read, which requires extra time for communication, which is not preferable in terms of communication efficiency. there were.
Especially, in a system that manages information of moving bodies moving at high speed such as trains and cars, the communication time is short, so
Poor communication efficiency hindered its practical application.

The present invention has been made in view of the above points, and an object of the present invention is to perform contactless communication between a fixed interrogator and a transponder held by a mobile body. In the mobile unit identification device to perform, extra transmission commands can be omitted and the communication format has a degree of freedom to improve data transmission efficiency, and even when the mobile unit moving at high speed holds the transponder, it is possible to ensure It is to provide a communication method capable of communication.

[0008]

According to the present invention, in order to solve the above problems, as shown in FIG. 2, a transponder 2 held by a mobile unit and assigned a unique identification number is provided.
And an interrogator 1 which communicates with the responder 2 using non-contact communication means such as radio waves. The interrogator 1 periodically transmits a command and an unmodulated signal alternately to the responder 2. When the transponder 2 receives a command sent from the interrogator 1, the transponder 2 modulates the unmodulated signal from the interrogator 1 according to the content of the reply data and sends the reply to the interrogator 1. As shown in, when the responder 2 receives the command COM2 from the interrogator 1, the responder 2 returns a response signal of the same content consisting of a plurality of frames to the interrogator 1 at the set frame interval T, and the interrogator 1 , predetermined length component signals from the responder 2 (e.g., 1 byte) has a timer means for measuring a is reset reception time each receiving (timer counter 18), a signal of a predetermined length fraction To receive
When the signal from the transponder 2 is not received for a time longer than the time required for, the delimiter between the frames is determined based on the measurement value of the time measuring means .

[0009]

In the communication system according to the present invention, the signal from the transponder 2 is reset each time a predetermined length of signal is received and the reception time is measured.
Since the time measuring means for measuring the time is provided, when the measured value of the time measuring means is equal to or longer than the time required to receive the signal of the predetermined length, it is possible to determine that the frame is a boundary. Therefore, the command from the interrogator 1 does not need to be transmitted in duplicate, and the communication efficiency can be improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing the configuration of a moving body identifying apparatus to which the present invention is applied. In the figure, 1 is an interrogator and 2 is a responder. The interrogator 1 includes a carrier wave oscillator 10 for oscillating an unmodulated carrier wave, a transmission / reception antenna 11 for transmitting an inquiry signal Q and a response signal A, and a PSK.
For the PSK modulator / demodulator 12 that performs signal modulation / demodulation, the FSK modulator / demodulator 13 that performs FSK signal modulation / demodulation, the shift register 14 for converting 1-byte parallel data and 1-bit serial data, and the shift register 14. Control circuit 15 for inputting / outputting transmitted / received data for each byte
A RAM 16 also serving as a reception buffer, a setting unit 17 for setting the operation of the interrogator 1, and a timer counter 18 for counting the reception time. The transponder 2 includes a transmitting / receiving antenna 21 for receiving the inquiry signal Q and transmitting the response signal A, a PSK modulating / demodulating unit 22 for modulating / demodulating a PSK signal, an FSK modulating / demodulating unit 23 for modulating / demodulating an FSK signal, and 1 A shift register 24 for converting parallel data of bytes and serial data of 1 bit, a control circuit 25 for inputting / outputting transmission / reception data for each byte to the shift register 24, and a RAM 26 also serving as a reception buffer. , A built-in battery 27 such as a lithium battery.

The operation of the moving body identifying apparatus shown in FIG. 2 will be described below. The 1-byte data set in the shift register 14 by the control circuit 15 of the interrogator 1 is serially sent to the FSK modulation / demodulation unit 13 bit by bit. In the FSK modulator / demodulator 13, the data "1" is associated with the first frequency f1 and the data "0" is associated with the second frequency f2.
To the FSK signal. In the PSK modulation / demodulation unit 12, the unmodulated carrier oscillated by the carrier oscillator 10 is PSK-modulated with the signal FSK-modulated by the FSK modulation / demodulation unit 13 and radiated from the transmission / reception antenna 11 as the interrogation signal Q. The interrogation signal Q received by the transmission / reception antenna 21 of the transponder 2 is demodulated by the PSK modulation / demodulation unit 22 to become an FSK signal. This FSK signal is demodulated by the FSK modulation / demodulation unit 23 to become "1" or "0" data, and the serial data of each 1 bit is converted into parallel data of 1 byte by the shift register 24, and the data is sent to the control circuit 25. Is entered. The data input to the control circuit 25 can be stored in the RAM 26 and RA
The stored contents of M26 can be read by the control circuit 25 and set in the shift register 24. Transponder 2
The 1-byte data set in the shift register 24 by the control circuit 25 is serially bit-by-bit FSK.
It is sent to the modulation / demodulation unit 23. The FSK modulator / demodulator 23 modulates the data "1" to the first frequency f1 and the data "0" to the second frequency f2 to modulate the FSK signal. In the PSK modulation / demodulation unit 22, the unmodulated carrier wave transmitted from the interrogator 1 is PSK-modulated with the signal FSK-modulated by the FSK modulation / demodulation unit 23 to obtain the response signal A.
Is re-radiated from the transmitting / receiving antenna 21. The response signal A received by the transmitting / receiving antenna 11 of the interrogator 1 is PSK.
The FSK signal is demodulated by the modulation / demodulation unit 12. This FSK signal is demodulated by the FSK modulation / demodulation unit 13 to become "1" or "0" data, and this 1-bit serial data is converted by the shift register 14 into 1-byte parallel data, which is sent to the control circuit 15. Is entered. The data input to the control circuit 15 can be stored in the RAM 16, and the storage content of the RAM 16 can be read by the control circuit 15 and set in the shift register 14. The operation of this mobile unit identification apparatus can be set by the setting unit 17, and the reply frame interval from the responder 2, the number of reply frames, the length of one frame, etc. can be set. These setting data are set as information in the command transmitted from the interrogator 1.

The setting contents will be described below. FIG. 3 shows a 1-byte command, and the operation of the responder 2 is set by the first bit B1 to the eighth bit B8 thereof. In this embodiment, the command contents that can be designated as commands are the distinction between reading the identification number of the responder or writing the data to the responder, whether or not the identification number of the responder is specified, the response interval from the responder, and the response. The number of reply frames from the device, the frame length of data read from the responder, the number of bytes of data written to the responder, and the like.
The respective contents will be described below.

First, the distinction between the reading of the identification number of the responder 2 and the writing of data to the responder 2 means whether the interrogator 1 performs the operation of reading the identification number of the responder 2 or other data, or , Which determines whether the operation of writing data from the interrogator 1 to the RAM 26 of the responder 2 is performed, and is selected by the first bit B1 of the command shown in FIG. 3, for example. Next, whether or not the identification number of the transponder 2 is designated is to select whether or not to perform the operation of designating the transponder 2 that should respond to the interrogation signal from the interrogator 1. Second bit B of the command shown in FIG.
2 is selected. When the identification number is designated, only the responder 2 having the identification number designated by 1 byte following the command responds to the inquiry signal from the interrogator 1. When the identification number is not designated, the transponders 2 that have received the interrogation signal from the interrogator 1 all perform the response operation. The reply interval is the length of the non-reply period provided between reply frames from the responder 2, and is specified in four ways by the third bit B3 and the fourth bit B4 of the command shown in FIG. 3, for example. It is what is done. When the reply interval is designated by the command from the interrogator 1, the responder 2 returns the reply frame at the designated interval. Further, the number of reply frames is the number of reply frames returned from the responder 2, and is specified in four ways by the fifth bit B5 and the sixth bit B6 of the command shown in FIG. 3, for example. When the number of replies is designated by the command from the interrogator 1, the responder 2 replies the designated number of reply frames. Next, the frame length of the data read from the responder 2 is the length of the data returned from the responder 2 several times in succession. For example, the seventh bit B7 and the eighth bit B8 of the command shown in FIG. Are specified in four ways. When the reply frame length is specified by the command from the interrogator 1, the responder 2 returns the data with the specified frame length. Furthermore, the number of bytes of data written to the responder 2 is
When writing data from the interrogator 1 to the responder 2, the number of bytes is designated. For example, as shown in FIG.
6 in the third bit B3 to the eighth bit B8 of the command shown in
It is specified in four ways. When the number of bytes of write data is designated by the command from the interrogator 1, the responder 2 writes the designated number of bytes of data as write data in the RAM 26 following the command from the interrogator 1. The parameters (1) to (4) are designated when the interrogator 1 reads the identification number and the like from the responder 2, and the parameters (1) are designated when writing data from the interrogator 1 to the responder 2. Is.

Next, the timer counter 18 of the interrogator 1
Is provided to determine the delimiter of the reply frame from the responder 2, and is reset every time one byte of normal data is received from the responder 2, and the reception time is counted from the reset time. If the count time of the timer counter 18 exceeds the reception time of 1 byte, it means that normal data has not been received for the time of 1 byte or more, and thus it can be determined that the reply frame is delimited.

1 (a) and 1 (b) are diagrams showing a communication format when the present invention is applied. FIG. 1A shows an inquiry signal Q, and as its command COM2, here, an identification number is not designated and the number of bytes of read data is 4
The instruction has the contents of byte, frame reply count 3 times, and reply interval T. Finally, a check code BCC is added to form the inquiry signal Q. FIG. 1B shows a response signal A from the responder 2, which is a command COM2 indicating the content of the response (the same command as the command of the inquiry signal Q),
Own identification number ID2, 4-byte data DT2 read from own RAM 26, and check code BC
C. In the illustrated format, the response signal A is composed of three frames, and the frame interval T is set to the time designated by the interrogator 1. On the side of the interrogator 1 that receives the response signal A, first, find out the byte of the same numerical value as the command COM2 located at the beginning of one frame, and then the found byte is the command located at the beginning of the reply frame. It is determined whether the data is the 1-byte data in the 4-byte data DT2. As a means for making the determination, every time 1 byte of normal data is received, the timer counter 18 for counting the length of the received signal is reset, and the count value of the timer counter 18 becomes 1 byte or more. Check location, that is, between frames. If the count value of the timer counter 18 is 1 byte or longer, the data can be regarded as a command at the beginning of a new frame.

Under the control of the control circuit 15, the interrogator 1 periodically sends a command COM2 and a check code BC.
C and an unmodulated carrier signal are alternately transmitted to the responder 2, and the response signal from the responder 2 receives the unmodulated carrier signal from the interrogator 1, modulates and re-radiates. Reply by. As a result, the transponder 2 does not need to have an oscillator and can be downsized and the capacity of the built-in battery 27 can be reduced. In addition, in this type of moving body identifying apparatus, since a carrier wave in the microwave band is generally used, the cost of the transponder 2 can be reduced by omitting the carrier wave oscillator of the transponder 2. . Transponder 2
The identification number and other data are stored in the RAM 26. Further, the reply data from the responder 2 is stored in the RAM 16 of the interrogator 1 a plurality of times, and after the reception operation is completed, the reply data is compared by the comparison function of the control circuit 15 configured by a microprocessor or the like, If the reply data match, it is judged as correct data. If the reply data do not match, communication is performed again. Alternatively, of the three reply data, when two match and only one mismatch, the matched two reply data are adopted as correct data. Thereby, the reliability of communication can be improved.

Further, in this embodiment, since the command COM2 having the same content as the command COM2 included in the inquiry signal is arranged at the head of the reply frame, the head of the frame can be surely checked. Even if the reply data DT2 included in the reply frame has the same numerical value as the command COM2, the timer counter 18 checks the frame delimiter.
Do not confuse both. Since the frame delimiter is double-checked in this way, the reply frame delimiter can be easily determined without transmitting the interrogation signal from the interrogator 1 for each reply frame delimiter. Therefore,
Since it is not necessary to arrange the inquiry signal between the reply frames, compared to the conventional communication format shown in FIG.
The communication time is shortened as a whole.

[0018]

According to the invention as set forth in claim 1, in a moving body identifying apparatus for identifying a moving body by performing contactless communication between a fixed interrogator and a responder held by the moving body, There is an advantage that the reliability of communication is improved by configuring the responder to send back the reply signal multiple times in response to the single question signal from the interrogator. by providing a timer means for measuring a reception time is reset each time it receives a when receiving the response signal of a predetermined length, when the time counting means for more than a predetermined time is not reset, 1
There is an effect that it is possible to easily determine that it is a delimiter between the response signal of one time and the response signal of the next time, and it is not necessary to insert a question signal between the response signals of each time, thereby improving communication efficiency. When applied to a mobile body identification device, data can be transmitted and received efficiently within a limited communication time, so a faster mobile body can be identified and a larger amount of data can be read from the mobile body. The effect is that you can.

According to the second aspect of the invention, the reply frame interval from the responder is set as the information in the command transmitted from the interrogator, so that the reply frame interval can be freely changed depending on the situation.

According to the third aspect of the invention, since the number of reply frames from the responder is set as the information in the command transmitted from the interrogator, there is an effect that the number of reply frames can be freely changed depending on the situation.

In the invention according to claim 4, since the length of one frame returned from the responder is set as information in the command transmitted from the interrogator, the length of one reply frame can be freely changed depending on the situation. There is.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a communication format according to an embodiment of the present invention.

FIG. 2 is a block circuit diagram showing the overall configuration of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of commands used in an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a conventional mobile body identification device.

FIG. 5 is an explanatory diagram showing a communication format in a conventional example.

[Explanation of symbols]

 1 Interrogator 2 Responder Q Question signal A Response signal 18 Timer counter

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takayuki Arai 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (56) References JP-A-4-208890 (JP, A)

Claims (4)

(57) [Claims] 1. A transponder, which is held in a mobile unit and is assigned a unique identification number, and an interrogator that communicates with the transponder using non-contact communication means. The interrogator is periodic. Command and unmodulated signal are alternately transmitted to the transponder, and when the transponder receives the command sent from the interrogator, it modulates the unmodulated signal from the interrogator according to the contents of the reply data and sends it to the interrogator. In the replying mobile object identification device, when the responder receives the command from the interrogator,
The interrogator is provided with the first control means for returning the response signal of the same content consisting of a plurality of frames to the interrogator at the set frame interval, and the interrogator is reset every time the signal from the transponder is received for a predetermined length. Time measuring means for measuring the reception time by
Total of the timer means when the signal from the responder for over the time required to receive a signal of a predetermined length amount is not received
And a second control means for determining a division between frames based on a measured value. 2. The communication system of the mobile unit identifying apparatus according to claim 1, wherein the reply frame interval from the responder is set as information in a command transmitted from the interrogator. 3. The communication system of a mobile unit identifying apparatus according to claim 1, wherein the number of reply frames from the responder is set as information in a command transmitted from the interrogator. 4. The communication system of a mobile body identification device according to claim 1, wherein the length of one frame returned from the responder is set as information in a command transmitted from the interrogator.