JPH0613932A - Mobile communication system - Google Patents

Abstract

PURPOSE:To implement normal communication with a responder regardless of the changeover operation to plural antennas provided to an interrogator. CONSTITUTION:An interrogator 10 sends an interrogation signal from a controller 20 through 1st and 2nd antennas 12, 14. A responder sends a response signal in response to the interrogation signal from the responder 10. A level deciding circuit 22 receives the response signals received by the antennas 12, 14 and decides a signal which has a higher level. A signal selection circuit 24 outputs the response signal discriminated by the level decided circuit 22 to the controller 20. Since the controller 20 receives alternatively the response signal with a higher level from the interrogator 10, the controller 20 requires no switching function to the antennas 12, 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system for transmitting / receiving data to / from a transponder provided in a mobile.

[0002]

2. Description of the Related Art As an example of this type of mobile communication system, for example, a transponder having a communication function is attached to a product carried on a carrier line, and an interrogator transmits an interrogation signal to the transponder. There is one that transmits and receives between the interrogator and the transponder, and processes the response signal received by the interrogator from the transponder by the control device.

That is, the interrogator transmits the interrogation signal through the antenna, and when the transponder is located in the communication area according to the movement of the mobile body, the interrogator receives the interrogation signal through the antenna and responds to the question. The response signal is transmitted through the antenna. As a result, the interrogator outputs the response signal received from the responder to the control device, so that the control device processes the response signal and outputs the data content to the host computer as necessary.

By the way, in recent years, there has been a demand for an increase in communication data as well as an increase in the speed of a carrier line, and the shortage of communication time is becoming a problem. Therefore, in order to deal with such a problem, a plurality of antennas are provided in the interrogator along the moving area of the product, and the response signal received by each antenna is output to the control device. In this case, the control device selects the antenna having the highest signal level of the response signal from the plurality of antennas provided in the interrogator.

[0005]

However, in the case of the above-mentioned conventional example, the control device must execute the switching operation for selecting the antenna at the same time as the reading operation of the response signal from the interrogator. Therefore, when the switching operation for the antenna is executed, the control device cannot read the response signal, which causes a problem that communication is interrupted.

The present invention has been made in view of the above circumstances. An object of the present invention is to communicate with a transponder by switching a plurality of antennas provided in an interrogator, and the communication will not be interrupted. It is to provide a mobile communication system.

[0007]

SUMMARY OF THE INVENTION The present invention provides a transponder for transmitting / receiving operations through a mobile antenna provided on a mobile unit and a plurality of fixed antennas provided along a moving area of the mobile unit. An interrogator to execute,
In a mobile communication system including a control device that controls the operation of the interrogator, a level determination circuit that determines the interrogator having the highest signal level among the response signals from the fixed antenna, and the level determination circuit. A signal selection circuit for selectively outputting the response signal judged by the judgment circuit to the control device is provided.

[0008]

[Operation] The interrogator transmits the interrogation signal through the antenna. Then, when the mobile body is located in the communication area, the transponder provided in the mobile body transmits a response signal according to the inquiry signal.

Since a plurality of interrogator antennas are provided along the moving area of the moving body, the transponder transmits and receives simultaneously with the plurality of antennas. At this time, the level determination circuit determines which of the response signals received by the antenna has the highest signal level. Then, the signal selection circuit selectively outputs the response signal determined by the level determination circuit to the control device. As a result, the control device can read the response signal having the highest signal level without switching the antenna.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 schematically shows the overall configuration. In FIG. 3, the interrogator 10 includes a first fixed antenna 12 and a second fixed antenna 14, and the fixed antennas 12 and 14 selectively transmit interrogation signals. A transponder 18 is attached to the moving body 16. Interrogator 10
The fixed antennas 12 and 14 provided in each of the fixed antennas 12 and 14 are arranged along the moving area of the moving body 16, and when the moving body 16 is located in the communication area of the fixed antennas 12 and 14 indicated by the chain double-dashed line, the interrogator Communication is performed between 10 and the responder 18. In this case, the first and second antennas 12, 14
The communication areas according to are set so as to partially overlap each other. Further, the interrogator 10 transmits the interrogation signal under the control of the control device 20 and outputs the response signal received from the responder 18 to the control device 20.

FIG. 1 shows the structure of the interrogator 10. In FIG. 1, the interrogator 10 is connected to the control device 20 via an input terminal 10a and an output terminal 10b. The interrogator 10 is configured to include a level determination circuit 22, a signal selection circuit 24, and a demodulator 26 in addition to the first fixed antenna 12 and the second fixed antenna 14.

Here, the first fixed antenna 12 and the second fixed antenna
Since the fixed antennas 14 have the same configuration, only the first fixed antenna 12 will be described and the description of the second fixed antenna 14 will be omitted. That is, in the first fixed antenna 12, the modulator 28 modulates the interrogation signal input from the control device 20 through the input terminal 10a by the carrier signal from the oscillator 30, and outputs the interrogation signal to the microstrip antenna 34 through the circulator 32. Detector 36
Detects the response signal received from the microstrip antenna 34 through the circulator 32 and outputs it to the level determination circuit 22.

The level decision circuit 22 is adapted to receive the response signals from the first and second fixed antennas 12 and 14, and decides which one of the input response signals has a larger signal level and outputs the decision result. To the signal selection circuit 24.
The signal selection circuit 24 is adapted to receive the response signals from the first and second antennas 12 and 14, and demodulates the response signal determined to have a high signal level based on the determination result of the level determination circuit 22. The signal is output to the control device 20 through the device 26 and the output terminal 10b.

The control device 20 executes the command sent to the responder 18 or the control of the operating time to the interrogator 10 and also processes the data received from the responder 18 to perform the necessary operation. The processed data is output to a host computer (not shown) or displayed on a display device.

FIG. 2 shows the structure of the responder 18. In FIG. 2, the control unit 38 inputs the interrogation signal received by the mobile antenna 40, which is a microstrip antenna, through the detector 42, and modulates the response signal in response to the interrogation content through the modulator 44 to microstrip antenna. Output to 40. In addition, the control unit 38
Exchanges data with the data memory 46.
The battery 48 supplies power to each circuit.

Next, the operation of the above configuration will be described. Since the control device 20 intermittently outputs the interrogation signal to the interrogator 10, the interrogation signal is transmitted from the first and second fixed antennas 12 and 14.

When the mobile unit 16 is located in the communication area of the first fixed antenna 12, the transponder 18 provided in the mobile unit 16 receives the interrogation signal through the mobile antenna 40, and then the identification number set by itself is received. Is transmitted through the mobile antenna 40. As a result, the first fixed antenna 12 of the interrogator 10 receives the response signal from the responder 18, and the level determination circuit 2 is passed through the detector 36.
Output to 2. At this time, although the response signal from the transponder 18 is output from the second fixed antenna 14 to the level determination circuit 22, the signal level thereof is lower than the signal level of the response signal from the first fixed antenna 12. Therefore, the level determination circuit 22 determines that the signal level of the response signal from the first fixed antenna 12 is higher,
The determination result is given to the signal selection circuit 24. Then, the signal selection circuit 24 outputs the response signal from the first fixed antenna 12 to the demodulator 26, so that the identification number is output from the demodulator 26 to the control device 20.

Then, the control device 20 which has inputted the identification number as described above judges whether the identification number is legitimate or not, and if it is legitimate, a write command (data write command) or a read command is issued. Data communication with the transponder 18 is executed by transmitting an inquiry signal indicating a command such as a command (data reading command) through the first and second antennas 12 and 14. At this time, the signal level of the response signal received by the first fixed antenna 12 and output to the control device 20 changes as shown in FIG. 4A as the moving body 16 moves.

Now, as the moving body 16 moves, the moving body 1
When 6 is located in the common communication area of the fixed antennas 12 and 14, the signal level of the response signal from the second fixed antenna 14 becomes higher (timing shown by A in FIG. 4). As a result, the signal selection circuit 24 outputs the response signal from the second fixed antenna 14 to the control device 20 according to the instruction of the level determination circuit 22, so that the control device 20 outputs the second response signal after the timing. The data communication is continued based on the response signal from the fixed antenna 14.

According to the above configuration, the interrogator 10 is
Since the level determination circuit 22 and the signal selection circuit 24 output the response signal having the higher signal level among the response signals from the first fixed antenna 12 and the second fixed antenna 14 to the control device 20, The first with the move
Even if the signal level of the response signal received by the second fixed antennas 12 and 14 varies, the response signal with the higher signal level is output to the control device 20. Therefore, unlike the conventional example in which the control device has a switching function for selecting one of the plurality of fixed antennas, the control device 20 does not need to have a switching function for selecting an antenna, and therefore the switching for the antenna is performed. Communication with the transponder 18 is not interrupted due to the operation.

[0021]

As is apparent from the above description, according to the mobile communication system of the present invention, the interrogator is provided with a level determining circuit for determining the response signal from the fixed antenna having the highest signal level. , A signal selecting circuit for selectively outputting the response signal judged by the level judging circuit to the control device is provided, so that in order to communicate with the responder by switching a plurality of antennas provided in the interrogator It has an excellent effect that communication is not interrupted.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an interrogator according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a transponder.

FIG. 3 is a diagram schematically showing the overall configuration.

FIG. 4 is a diagram showing a change in signal level of a response signal due to movement of a moving body.

[Description of Reference Signs] 10 is an interrogator, 12 and 14 are fixed antennas, 16 is a moving body, 18 is a responder, 20 is a control device, and 40 is a mobile antenna.

Claims (1)

[Claims] 1. A transponder that is provided in a mobile body and performs a transmission / reception operation through a mobile antenna, an interrogator that performs a transmission / reception operation through a plurality of fixed antennas provided along a moving area of the mobile body, and an interrogator. In a mobile communication system provided with a control device for controlling the operation of the interrogator, the interrogator is a level decision circuit for deciding the response signal from the fixed antenna having the highest signal level, and the level decision circuit. And a signal selection circuit that selectively outputs the response signal determined by the above to the control device.