JP5363519B2 - Communication system, reader / writer, non-contact IC card, communication method - Google Patents

Description

  The present invention relates to a communication system, a reader / writer, a non-contact IC card, and a communication method.

  In the prior art, as specified in ISO / IEC14443, a dedicated non-contact IC card is required for each non-contact interface supported by the reader / writer (for example, see Non-Patent Documents 1 and 2). For example, in ISO / IEC14443 type A, type A reader / writer and type A card like a cigarette card, and in ISO / IEC14443 type B, type B reader / writer and type B card like railroad card, Even for traffic cards such as ticket gates and bus fare boxes, contactless IC cards that correspond to reader / writers of specific specifications were required.

  There are also non-contact IC cards that support a plurality of non-contact interfaces (see, for example, Non-Patent Document 3), but even in the non-contact IC card, it is necessary to determine one of the non-contact interfaces as an initial setting. Yes, the contactless interface could not be switched dynamically. In the following description, the above contactless interface types are referred to as contactless interface types A, B, and A.

  As a conventional patent relating to a method of automatically switching a non-contact interface in a non-contact IC card that supports a plurality of non-contact interfaces, for example, there is a method described in Patent Document 1.

"JIS IC Card without External Terminals, Proximity Type Part 2: Power Transmission and Signal Interface", Japanese Standards Association, April 20, 2001 "JIS card without external terminal, proximity type, Part 3: Initialization and collision prevention", Japanese Standards Association, September 20, 2001 "AE-4 Series", Renesas Electronics, [online], [Search February 14, 2011], Internet <http://japan.renesas.com/products/iccard/ae4/ae4_root.jsp>

Japanese Patent No. 38197883

  The technique described in Patent Document 1 is to search and determine a modulation method and a coding method using the repeatability when receiving a modulation signal from a reader / writer on the non-contact IC card side. There is a problem that it takes a long time and a circuit of a non-contact IC card chip becomes complicated.

  Accordingly, an object of the present invention made in view of such a point is that a non-contact IC card is used for communication between a reader / writer that communicates using a non-contact interface and a non-contact IC card that supports a plurality of non-contact interfaces. To provide a communication system, a reader / writer, a non-contact IC card, and a communication method capable of determining a non-contact interface to be used at a physical level layer and switching at high speed.

  A communication system according to the present invention is a communication system including a reader / writer and a non-contact IC card, wherein the reader / writer is a tone that oscillates a tone frequency corresponding to a modulation unit that modulates a carrier and a non-contact interface to be used. An oscillation unit; and a controller that controls the tone oscillation unit, wherein the controller supports the contactless interface to the tone oscillation unit when transmitting a polling command to the contactless IC card through the contactless interface. The tone frequency is oscillated, and the modulation unit performs ASK modulation on the polling command and places the carrier on the carrier, and amplitude-modulates the carrier with the tone frequency. The contactless IC card has a plurality of contactless A transmitter / receiver corresponding to the interface and the reader / writer A tone signal receiver that detects the carrier and determines the amplitude modulation frequency of the carrier, and the transmitter / receiver communicates with the reader / writer through a non-contact interface corresponding to the amplitude modulation frequency. Is what you do.

  The reader / writer according to the present invention is a reader / writer that performs communication using a non-contact interface, a modulation unit that modulates a carrier, a tone oscillation unit that oscillates a tone frequency corresponding to the non-contact interface, and the tone A controller for controlling the oscillation unit, and the controller causes the tone oscillation unit to oscillate the tone frequency corresponding to the non-contact interface when transmitting a polling command to the non-contact IC card through the non-contact interface. The modulation unit performs ASK modulation on the polling command and places it on the carrier, and amplitude-modulates the carrier with the tone frequency.

  Further, the non-contact IC card according to the present invention is a non-contact IC card corresponding to a plurality of non-contact interfaces, and detects a carrier from a transmitter / receiver corresponding to the plurality of non-contact interfaces and a reader / writer, A tone signal receiving unit that determines an amplitude modulation frequency of the carrier, and the transmission / reception unit communicates with the reader / writer through a non-contact interface corresponding to the frequency of the amplitude modulation.

  The communication method according to the present invention is a communication method between a reader / writer and a non-contact IC card, and the processing procedure of the reader / writer transmits a polling command to the non-contact IC card by a non-contact interface to be used. Oscillating a tone frequency corresponding to the non-contact interface, and ASK-modulating the polling command and placing it on a carrier, and amplitude-modulating the carrier according to the tone frequency. The processing procedure of the IC card includes a step of detecting the carrier from the reader / writer, a step of determining an amplitude modulation frequency of the carrier, and a non-contact interface corresponding to the amplitude modulation frequency. Performing the communication.

  According to the communication system, the reader / writer, the non-contact IC card, and the communication method according to the present invention, the non-contact is performed between the reader / writer that communicates with the non-contact interface and the non-contact IC card that supports a plurality of non-contact interfaces. The IC card can switch the contactless interface used for communication at a high speed by judging the physical level layer.

FIG. 1 is a diagram showing an outline of a communication system according to an embodiment of the present invention. FIG. 2 is a diagram showing functional blocks of the reader / writer according to the embodiment of the present invention. FIG. 3 is a diagram illustrating an example of amplitude modulation by the reader / writer according to the embodiment of the present invention. FIG. 4 is a diagram showing functional blocks of the non-contact IC card according to one embodiment of the present invention. FIG. 5 is a diagram showing a mounting example of the non-contact IC card according to the embodiment of the present invention. FIG. 6 is an operation flowchart of the reader / writer according to the embodiment of the present invention. FIG. 7 is an operation flowchart of the non-contact IC card according to the embodiment of the present invention. FIG. 8 is a diagram showing an operation sequence of the communication system according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing an operation image of a communication system according to an embodiment of the present invention. Conventionally, various services using non-contact IC cards such as vending machines, administrative services, and railway ticket gates use different non-contact interfaces such as non-contact interface type A, B, and 丙. In addition, a reader / writer specialized in a non-contact interface and a non-contact IC card are required. According to the present invention, a single non-contact IC card 20 can communicate with reader / writers 10 (10A, 10B, 10C) having different non-contact interfaces. Thus, if an application corresponding to a non-contact interface of various services is installed in the non-contact IC card 20, a non-contact IC card that can receive various services can be realized with one sheet.

  FIG. 2 shows a schematic configuration of a reader / writer according to an embodiment of the present invention. The reader / writer 10 includes a carrier oscillation unit 11, a modulation unit 12, an output unit 13, a controller 14, a data transmission unit 15, a tone oscillation unit 16, a demodulation unit 17, and an antenna unit 18. The reader / writer 10 places a low-frequency tone signal on an AC magnetic field (carrier) generated from the antenna unit 18 as a method of transmitting the supported non-contact interface type to the non-contact IC card 20. The reader / writer 10 determines a tone signal frequency (hereinafter referred to as tone frequency) in advance according to the non-contact interface type. For example, in the case of the non-contact interface type A, the tone frequency can be set to 1 KHz, in the case of B, the tone frequency can be set to 3 KHz, and in the case of 丙, the tone frequency can be determined to be 5 KHz.

  As shown in FIG. 2, the reader / writer 10 has a tone oscillating unit 16, and switching of oscillation ON (start) and OFF (stop) and oscillation frequency of the tone oscillating unit 16 can be controlled from the controller 14. For example, when the reader / writer 10 is operated by the non-contact interface type B, the controller 14 instructs the tone oscillator 16 to oscillate at a tone frequency of 3 KHz. Further, at the time of polling for capturing the non-contact IC card 20, the controller 14 instructs the tone oscillation unit 16 to turn on the oscillation.

  FIG. 3A shows a magnetic field waveform generated from the antenna unit 18 when the oscillation of the tone oscillating unit 16 is ON. When the oscillation of the tone oscillation unit 16 is ON, the modulation unit 12 performs AM (Amplitude Modulation) modulation (amplitude modulation) on the carrier in accordance with the tone signal (tone frequency) from the tone oscillation unit. The controller 14 turns on the oscillation of the tone oscillating unit 16 when transmitting a polling signal to the non-contact IC card 20. In this case, for example, a 3 KHz tone signal (tone frequency) is mounted on the carrier in the form of AM modulation. , 106 Kbps polling signal is loaded in a form of ASK (Amplitude Shift Keying) modulation. Note that the modulation degree of AM modulation is preferably made small so as not to affect power transmission and polling signal transmission. Further, the frequency of the tone signal is preferably lowered to such an extent that does not affect polling signal transmission.

  When the reader / writer 10 receives a polling response of a predetermined contactless interface type from the contactless IC card 20, the demodulator 17 demodulates the polling response and outputs it to the controller 14. When the controller 14 confirms the polling response from the non-contact IC card 20, the controller 14 stops the oscillation operation of the tone oscillation unit 16 (oscillation OFF).

  FIG. 3B shows a magnetic field waveform generated from the antenna unit 18 when the oscillation of the tone oscillation unit 16 is OFF. When the oscillation of the tone oscillation unit 16 is OFF, the modulation unit 12 performs ASK modulation on the carrier from the carrier oscillation unit 12 and places the data from the data transmission unit 15 on the carrier, but does not perform AM modulation with the tone signal. . The modulated carrier is amplified by the output unit 13 and transmitted from the antenna unit 18 to the non-contact IC card 20. In this case, the magnetic field waveform generated by the antenna unit 18 is a conventional magnetic field waveform that is not subjected to AM modulation by the tone signal, as shown in FIG.

  FIG. 4 shows a schematic configuration of a non-contact IC card according to an embodiment of the present invention. The non-contact IC card 20 includes an antenna unit 21, changeover switches 22 and 26, and transmission / reception units corresponding to various non-contact interfaces (communication IF type A / O transmission / reception unit 23, communication IF type B / O transmission / reception unit 24, communication IF type 丙 transmission / reception) Unit 25) and an application processing unit 27. Further, the non-contact IC card 20 includes a tone signal receiving unit 30 that demodulates the tone signal from the reader / writer 10. The tone signal receiving unit 30 includes a tone detecting unit 31 that detects a tone signal that has been AM modulated on a carrier, an amplifier unit 32 that amplifies the detected tone signal until the level can be determined by the comparator, and a comparator unit 33 that determines the level. And a counter unit 34 that counts the frequency of the tone signal digitized by the comparator, and a tone frequency determination unit 35 that determines the tone frequency from the count result of the counter unit. The tone frequency determination unit 35 controls the changeover switches 22 and 26 to connect the corresponding transmission / reception units (23, 24, 25) based on the determination result of the tone frequency. When the transmission / reception units (23, 24, 25) corresponding to the predetermined non-contact interface are connected by the changeover switches 22 and 26, data transmission / reception by the predetermined non-contact interface becomes possible, and the application processing unit 27 It becomes possible to execute processing.

  FIG. 5 shows an example of mounting the non-contact IC card 20 shown in FIG. Each functional unit of the non-contact IC card 20 shown in FIG. 5 is roughly divided into hardware H and firmware F. The hardware H and firmware F are respectively a tone signal receiving unit 30, a receiving unit 40, and a transmitting unit 50. These functional units are included. The hardware H also includes a clock recovery unit 61 that generates a transmission clock, a subcarrier generation unit 62 that generates subcarriers, and a power supply unit 63 that rectifies carriers from the reader / writer 10 and obtains power. . The firmware F includes an application processing unit 71 that performs predetermined application processing.

  The tone signal receiving unit 30 is a tone signal demodulation system. First, the tone detection unit 31 detects a reception signal taken from the antenna unit 21. The tone detector 31 is simply composed of a diode and a low-pass filter comprising a capacitor (C) and a resistor (R). The time constant by C and R of the tone detection unit 31 is several tens to several hundreds of time constants compared to the command detection unit 41 of the reception unit 40 (data demodulation system) so as to be suitable for demodulation of a tone signal of several KHz. It is selected to be about twice as long. The amplifier section 32 amplifies the detected tone signal to about several tens to several hundred millivolts so that it can be digitized by the comparator 33, and the gain is about several tens of times. The tone signal digitized by the comparator 33 is counted by the counter 34 that is gate-controlled by the tone frequency determination unit 35 realized by the firmware F on the controller, and the tone frequency is specified. The tone frequency determination unit 35 by the firmware F transmits the determination result of the tone frequency to the reception processing unit 48 and the transmission processing unit 51. The reception processing unit 48 and the transmission processing unit 51 switch the hardware H by issuing a modulation unit (53, 54, 55) and demodulation unit (44, 45, 46) switching signal to the hardware H, respectively. At the same time, transmission / reception processing according to the contactless interface type is performed.

  Specifically, in the transmission unit 50, the transmission processing unit 51 switches the change-over switches 52 and 56 according to the determination result of the tone frequency, and the modulation unit (communication IF type first-order modulation unit 53) according to a predetermined non-contact interface. The communication IF type B modulation unit 54 and the communication IF type B modulation unit 55) are connected. For example, when the tone frequency is 3 KHz, the transmission processing unit 51 switches the changeover switches 52 and 56 so that the communication IF type B modulation unit 54 is connected. The modulators (53, 54, 55) modulate the subcarriers from the subcarrier generator 62 and transmit a polling response from the antenna unit 21 to the reader / writer 10 through the load modulator 57.

  In the reception unit 40, the reception processing unit 48 switches the selector switches 43 and 47 according to the tone frequency determination result, and the demodulation unit (communication IF type A demodulator 44, communication IF type B demodulator) according to a predetermined non-contact interface. Unit 45 and communication IF type 丙 demodulation unit 46). For example, when the tone frequency is 3 KHz, the reception processing unit 48 switches the selector switches 43 and 47 so that the communication IF type B demodulator 45 is connected. The demodulation unit (44, 45, 46) demodulates the reception signal that has passed through the command detection unit 41 and the amplifier unit 42, and the reception processing unit 48 supplies the demodulated reception signal to the application processing unit 71.

  FIG. 6 is a processing flow of the reader / writer 10. When the reader / writer 10 is activated, it first determines one non-contact interface among non-contact interfaces such as A, B, and T, which are compatible communication interface types, by setting from the outside (step S101). Next, the carrier oscillating unit 11 starts carrier generation (step S102), and the controller 14 turns on the oscillation of the tone oscillating unit 16 and at the same time, determines the oscillation frequency (tone) of the tone oscillating unit 16 according to the determined non-contact interface. Frequency) is set (step S103). The modulation unit 12 starts AM modulation according to the tone frequency from the tone oscillation unit 16 (steps S104, S108, and S112). For example, the modulation unit 12 AM-modulates the carrier with a tone frequency of 1 KHz when the contactless interface type is A, and AM-modulates the carrier with a tone frequency of 3 KHz when the contactless interface type is B. When the contact interface type is 丙, the carrier is AM-modulated with a tone frequency of 5 KHz. Next, the modulation unit 12 starts ASK modulation of the polling command from the data transmission unit 15 (steps S105, S109, and S113). The above processing is performed instantaneously, and there is no problem even if the non-contact IC card 20 is held over this processing period in operation. In this state, the card reader 10 waits for a polling response from the non-contact IC card 20 (steps S106, S110, S114).

  When the non-contact IC card 20 is held over the reader / writer 10, a non-contact interface adapted on the non-contact IC card 20 side is selected by the processing flow of FIG. 7 to be described later, and a polling response according to the determined non-contact interface is transmitted. It will be. In the reader / writer 10, when the response from the non-contact IC card 20 is received, the controller 14 issues an instruction to turn off the oscillation of the tone oscillating unit 16 in order to stop AM modulation by the tone signal (steps S107, S111, S115). Thereafter, the reader / writer 10 performs communication according to the standard of the conventional non-contact IC card until data transmission / reception is completed (steps S116 and S117).

  FIG. 7 is a processing flow of the non-contact IC card 20. The non-contact IC card 20 attempts to detect a tone signal before entering the polling reception process. When the carrier from the reader / writer 10 is received and power is supplied to the non-contact IC card 20, the tone signal receiving unit 30 starts to operate, and AM signals are detected from the carrier to acquire a tone signal (step S201). Next, the tone signal receiving unit 30 starts counting the digitized tone signal. Specifically, the tone signal receiving unit 30 counts the pulses of the tone signal digitized by the counter during a predetermined gate period, and measures the tone frequency from the count number (step S202).

  When the tone signal receiving unit 30 determines the frequency of the tone signal, the tone signal receiving unit 30 switches the connection of the changeover switches 22 and 26 to the corresponding non-contact interface transmitting / receiving unit (23, 24, 25) (steps S203, S206, S209). Specifically, the tone signal receiving unit 30 switches the non-contact interface to the former when the tone frequency is 1 KHz, switches the non-contact interface to the second when the tone frequency is 3 KHz, and the non-contact interface when the tone frequency is 5 KHz. Switch the contact interface to 丙. Note that the processing of the transmission / reception units (23, 24, 25) corresponding to various non-contact interfaces conforms to the standard of conventional non-contact IC cards. The non-contact IC card 20 receives polling from the reader / writer 10 through the connected transmission / reception unit (23, 24, 25), and transmits a polling response to the reader / writer 10 (steps S204, S207, S210). Thereafter, the non-contact IC card 20 communicates with the reader / writer 10 through the non-contact interface determined by the tone frequency (steps S205, S208, and S211).

  FIG. 8 is a processing flow of a communication system including the reader / writer 10, the non-contact IC card 20, and the host device 80. The host device 80 includes a reader / writer 10 such as a ticket gate or a POS system, and performs various controls on the reader / writer 10.

  The host device 80 performs initial setting of the reader / writer 10 after power-on (step S301). The initial setting includes the setting of the contactless interface type used in the service. Upon receiving the initial setting command from the host device 80, the reader / writer 10 determines the contactless interface type, and returns an initial setting response indicating that the contactless interface has been determined to the host device 80 (step S302). Thereafter, the reader / writer 10 waits for a command from the host device 80.

  Upon receiving the initial setting response from the reader / writer 10, the upper device 80 transmits a card search command to the reader / writer 10 in order to search for a non-contact IC card (step S303). When the host device 80 issues a card search command, the reader / writer 10 starts carrier transmission using a magnetic field (step S304). The reader / writer 10 starts AM modulation by a tone signal corresponding to the contactless interface type and ASK modulation by a polling command for the contactless IC card almost simultaneously (steps S305 and S306). At this time, as shown in FIG. 3A, a tone signal is AM-modulated on a carrier by a magnetic field at several KHz, and a polling command of several tens of bytes is ASK-modulated at intervals of several tens of milliseconds at a communication speed of several hundred Kbps. It becomes a state.

  Here, when the non-contact IC card 20 with the non-contact interface switching function enters the magnetic field of the reader / writer 10, the non-contact IC card 20 rectifies the carrier to obtain a power source and starts operation (step S307). ). First, the non-contact IC card 20 performs AM detection on the carrier and acquires a tone signal (step S308). When the tone signal receiving unit 30 determines the frequency of the tone signal, the contactless IC card 20 selects a contactless interface corresponding to the tone frequency (step S309). When the selection is completed, the contactless IC card 20 detects a carrier by the selected contactless interface and receives a polling command (step S310).

  The non-contact IC card 20 processes the polling command and transmits a polling response according to the selected non-contact interface to the reader / writer (step S311). When the reader / writer 10 receives the polling response in which the contactless interface is uniquely selected, the reader / writer 10 notifies the host device 80 that the card has been detected and stops AM modulation by the tone signal (step S312). Thereafter, data transfer is performed in the same manner as the conventional non-contact IC card communication. The host device 80 transmits a data transfer command corresponding to predetermined application processing to the reader / writer 10 (step S313). The reader / writer 10 transfers the data transfer command to the non-contact IC card 20 (step S314). The magnetic field waveform at this time is in the state shown in FIG. The non-contact IC card 20 performs predetermined application processing (step S315), and transmits a data transfer response to the reader / writer 10 and the host device 80. Thereafter, the processing of each device ends (steps S316, S317, and S318).

  As described above, according to the present embodiment, in the reader / writer 10, the controller 14 oscillates the tone frequency corresponding to the non-contact interface used for the tone oscillating unit 16 when transmitting the polling command to the non-contact IC card. The modulation unit 12 performs ASK modulation on the polling command and places it on the carrier, and amplitude-modulates the carrier with the tone frequency. As a result, the reader / writer 10 can inform the contactless IC card 20 of the type of contactless interface used by the reader / writer 10 on the physical level layer.

  The non-contact IC card 20 detects the carrier from the reader / writer 10 to determine the amplitude modulation frequency of the carrier, and communicates with the reader / writer 10 through a non-contact interface corresponding to the amplitude modulation frequency. . Thereby, the non-contact IC card 20 can determine the non-contact interface used by the reader / writer 10 in the physical level layer.

  That is, in the communication system including the reader / writer 10 and the contactless IC card 20 according to the present embodiment, the contactless interface type supported by the reader / writer 10 in the contactless IC card 20 is determined at the physical layer level, and contactless. Since the interface can be switched, it is possible to provide a high-speed service that does not make the user feel the type of contactless interface used and the interface switching time.

  Further, the non-contact IC card 20 transmits a response to the polling command to the reader / writer 10, and the controller 14 of the reader / writer 10 stops the operation of the tone oscillating unit 16 when receiving the response to the polling command. Thereby, after the non-contact IC card 20 determines the type of the non-contact interface, communication according to the conventional standard can be performed.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, functions included in each member, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined or divided into one. Is possible.

DESCRIPTION OF SYMBOLS 10 Reader / writer 11 Carrier transmission part 12 Modulation part 13 Output part 14 Controller 15 Data transmission part 16 Tone transmission part 17 Demodulation part 18 Antenna part 20 Non-contact IC card 21 Antenna part 22 Changeover switch 23 Communication IF type former transmission / reception part 24 Communication IF Type B Transmit / Receive Unit 25 Communication IF Type 丙 Transmit / Receive Unit 26 Changeover Switch 27 Application Processing Unit 30 Tone Signal Receiving Unit 31 Tone Detection Unit 32 Amplifier Unit 33 Comparator 34 Counter 35 Tone Frequency Determination Unit 40 Receiving Unit 41 Coverage Line Detection Unit 42 Amplifier Unit 43 changeover switch 44 communication IF type A demodulator 45 communication IF type B demodulator 46 communication IF type 丙 demodulator 47 changeover switch 48 reception processing unit 50 transmission unit 51 transmission processing unit 52 changeover switch 53 communication F type upper modulator 54 communication IF type Otsu modulation section 55 communication IF type Hei modulation unit 56 changeover switch 57 load modulator 60 power supply unit 61 clock reproducing unit 62 subcarrier generator 71 application processor H Hardware F firmware

Claims (7)

A communication system including a reader / writer and a contactless IC card,
The reader / writer is
A modulator for modulating the carrier;
A tone oscillator that oscillates the tone frequency corresponding to the non-contact interface to be used;
A controller for controlling the tone oscillation unit,
The controller, when transmitting a polling command to the non-contact IC card by the non-contact interface, causes the tone oscillation unit to oscillate the tone frequency corresponding to the non-contact interface,
The modulation unit performs ASK modulation on the polling command and places the carrier on the carrier, and amplitude-modulates the carrier with the tone frequency,
The non-contact IC card is
A transceiver that supports multiple contactless interfaces;
A tone signal receiving unit that detects the carrier from the reader / writer and determines the frequency of amplitude modulation of the carrier; and
The transmission / reception unit communicates with the reader / writer through a non-contact interface corresponding to the frequency of the amplitude modulation. The transmitting / receiving unit of the non-contact IC card transmits a response to the polling command to the reader / writer by the determined non-contact interface,
The communication system according to claim 1, wherein the controller of the reader / writer stops the operation of the tone oscillating unit when receiving a response to the polling command. A reader / writer that performs communication using a non-contact interface,
A modulator for modulating the carrier;
A tone oscillator that oscillates a tone frequency corresponding to the non-contact interface;
A controller for controlling the tone oscillation unit,
The controller, when transmitting a polling command to the non-contact IC card by the non-contact interface, causes the tone oscillation unit to oscillate the tone frequency corresponding to the non-contact interface,
The modulation unit is a reader / writer that performs ASK modulation on the polling command and places the carrier on the carrier, and amplitude-modulates the carrier with the tone frequency.   The reader / writer according to claim 3, wherein the control unit stops the operation of the tone oscillating unit when receiving a response to the polling command from the contactless card. A non-contact IC card corresponding to a plurality of non-contact interfaces,
A transceiver corresponding to the plurality of non-contact interfaces;
A tone signal receiving unit that detects a carrier from a reader / writer and determines the frequency of amplitude modulation of the carrier,
The transmission / reception unit is a non-contact IC card that communicates with the reader / writer through a non-contact interface corresponding to the frequency of the amplitude modulation. A communication method between a reader / writer and a non-contact IC card, wherein the processing procedure of the reader / writer is:
Oscillating a tone frequency corresponding to the non-contact interface when transmitting a polling command to the non-contact IC card by the non-contact interface to be used;
And ASK-modulating the polling command onto a carrier, and amplitude-modulating the carrier with the tone frequency.
The processing procedure of the non-contact IC card is as follows:
Detecting the carrier from the reader / writer;
Determining the frequency of amplitude modulation of the carrier;
Communicating with the reader / writer by a non-contact interface corresponding to the frequency of the amplitude modulation. The communication method according to claim 6, wherein the processing procedure of the reader / writer includes a step of stopping the operation of the tone oscillating unit when receiving a response to the polling command from the contactless card.

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