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The specifications of all payment systems concerning contactless cards are based on the ISO / IEC 14443 standard “Identification Cards - Contactless integrated circuit (s) cards - Proximity cards”. The standard consists of four parts, which appeared at different times between April 2000 and July 2001:
The second part of the standard (ISO 14443 - Part 2. Radio frequency characteristics and signal interface) defines the radio frequency characteristics of signals and signal interfaces (modulation and bit coding methods), including:
The 13.56 MHz carrier belongs to the frequency range known as the “ISM frequency” (Industrial, scientific and medical equipment). It does not interfere with industrial emissions, provides a high data transfer rate (in the order of 10 Mbit / s), as well as the ability to implement an LC circuit on the card with a frequency within 12-18 MHz.
To transmit digital information from the reader to the card, the method of amplitude modulation (ASK modulation) is used. There are two most common varieties of ISO 14443: Type A and Type B. ISO 14443 Type A uses 100% ASK modulation and a modified Miller code, in which the transmitted signal level most of the time takes the highest value and drops to zero at very short time (2-3 µs) in the first half of the bit time when transmitting bit “0” or in the second half of transmitting a bit when transmitting bit “1”. In addition, when sequential bits' G and '0' are transmitted one after another, the pause when encoding the '0' bit is not used to reduce the signal spectrum width. This also increases the accumulation of energy by the card from the reader signal (on the capacitor,
ISO 14443 Type B uses the 10% ASK modulation method and NRZ code, in which the carrier amplitude reaches its maximum value for the transmission of a binary '1', and the amplitude of the radio signal is reduced to about 81.8% of the signal level during the transmission of '0' used when transmitting bit '1'. Thus, using the ISO 14443 Touré B standard, the card is constantly “charged” with energy.
To transfer data from the card to the reader, a load modulation method is used. Its essence lies in the use of the so-called load resistance, which can be included in the circuit of the resonant circuit of the microcircuit and excluded from it. Turning on / off the load resistance to / from the circuit leads to a change in the characteristics of the resonant circuit of the microcircuit, and hence the value of the amplitude of the field generated by it. Since the resonant circuits of the reader and the microcircuit form a transformer connection, this field change is reflected in the performance of the reader and can be measured on the reader side by, for example, measuring the current in the reader's antenna.
Turning on / off the load resistance, obviously, can be "tied" to the signal transmission from the card to the reader. The return channel signal (from the card to the reader), generated using the load modulation method, can be modulated on a subcarrier with a frequency of 847.5 kHz. In this case, if A is the current level of the transmitted signal, ω and O are the cyclic frequencies of the carrier and subcarrier, respectively, then the signal level Z (t) at time t is represented by the expression:
Z (t) = A (1 + m • cos O • t) • coscot =
- A cos cot + - ^ - cos (co + Q) t 4- ^^ - cos (co - Q) t.
In the return channel of the ISO 14443 Type A standard, the Manchester code is used to encode the signal, in which the information bit is encoded with a discrete signal, which is a step function. To represent the 'G bit, the first half of the rung takes the minimum constant value, and the second - the maximum value. Conversely, bit '0' is represented by a rung, the first half of which is at the maximum constant value and the second half is at the minimum value.
To transmit the Manchester encoded signal in the return channel, the load modulation with the subcarrier used in the On-Off Keying mode is used. The latter means that the load modulation is "turned on" to transmit the low level of the Manchester code step (Fig. 7.6). In the figure, PCD stands for Reader and PICC stands for Proximity Card.
In the ISO 14443 Type B return channel, the bits are encoded using the already mentioned NRZ code. Load modulation is used to generate the transmitted signal. To transmit the signal, phase modulation of the signal from the subcarrier is used (see Fig. 7.6).
Let us now dwell on one common myth, which is that ISO 14443 Type B cards, due to the 10% amplitude modulation method used in them, are energetically much more efficient (they get more energy from the reader's radiation) in comparison with ISO 14443 Type B cards. A. Indeed, the ISO 14443 Type A map uses a modified Miller code in the forward link. The bit time for a transmission rate of 106 kbps is approximately 9.4395 µs. During the transmission of a bit when using the Mil-
Rice. 7.6. ISO 14443 forward and reverse waveform
The pause, during which the reader does not transmit a signal to the card, takes about 2-3 microseconds. For calculations, we will assume that the pause is 30% of the transmission time of a bit of information. Since when the sequence of bits '1', '0' appears, the pause is not used at all, but in all other cases it is used, it is easy to obtain that the average signal power received by the card during the data transmission by the reader is 3 1
067A • + A • -4- = 0.775 • A, where A is the power of the signal received
card during carrier transmission.
ISO 14443 Type B charts use NRZ code and 10% amplitude modulation. Since the signal power is proportional to the square of its amplitude, the average power of the modulated signal received by the card during data transmission by the reader is in this case (0.818) 2 • A • y + A • y = 0.835 • A.
From this we can draw the following conclusion: ISO 14443 Type B cards with the same parameters of the transmitter and reader antenna allow you to receive about 7% more energy than ISO 14443 Type A cards during data transfer from the reader to the card.
However, as the measurements of Gemalto specialists show (Fig. 7.7), the transfer of data from the reader to the card accounts for less than 15% of the total time spent by the contactless card in the working area of the reader. The rest of the time, the card receives the reader's carrier signal, which is independent of the card type. It follows that the gain in the average signal power received by the ISO 14443 Type B card from the reader during the processing of the operation does not exceed 1%!
The third part of the ISO 14443 protocol (ISO 14443 - Part 3. Initialization and anti-collision procedures) defines:
• card initialization procedures: procedures for polling cards by a reader, selecting a card for operation, as well as formats used for polling and selecting commands;
Contactless Contact
Transaction Transaction
Rice. 7.7. Transaction processing time via contact and contactless card interfaces
• procedures for resolving possible conflicts between several contactless cards located in the working area of the reader, competing for the right to work with the reader. The procedures ensure that the reader operates with exactly one card at a time.
The ISO 14443 standard uses two widespread collision resolution methods - clocked ALOHA (for ISO 14443 Type B cards) and a tree-based search algorithm by chip ID (for ISO 14443 Type A cards).
Finally, the fourth part of the ISO 14443 standard (ISO 14443 - Part 4. Data transfer protocol) defines a high-level half-duplex block protocol for transferring data between the card and the reader (T = CL), similar to the T = 1 protocol. The protocol defines the encapsulation of data, the format of data blocks, procedures for dividing data into blocks, procedures for detecting errors (ISO / IEC 13239) and recovering corrupted data. The T = CL protocol provides support for ISO 7816-4 packet exchange (APDUs) and application selection procedure (ISO 7816-5), making it easy to use the same application in both contactless and contact modes.
The ISO 14443 standard defines the value of the data transfer rate between the reader and the card equal to 106 Kbps. At the same time, transmission rates of 212 Kbps, 424 Kbps and 848 Kbps are technically available today. The issue of using speeds above 848 Kbps is being actively discussed. At the same time, in practice, for reasons of energy saving of the contactless card microcircuit, the speed of 106 Kbps is most often used.
In the ISO 14443 standard, to ensure the protection of transmitted data from errors, an error-correcting coding algorithm is used, as defined in the ISO / IEC 13239 standard. The algorithm is based on the extended cyclic Hamming code, given by the generating polynomial g (x) = x 16 4- x 12 + x 5 + 1 (this means that the check sequence generated by the code is 2 bytes in size).
It is easy to prove that the code distance (the minimum Hamming distance between any two different codewords) of this cyclic code is 4 (the minimum weight (number of ones) of a nonzero codeword is 4). It follows that the code used is able to reliably detect in the received data block any single, double errors, as well as any errors of odd multiplicity.
It is not guaranteed that the code is capable of detecting other group errors as well. The ability of the code to correct any errors of odd multiplicity follows from the fact that, obviously, all codewords of the code under consideration have an even weight.
Extended Hamming is used in the ISO 14443 standard in error detection mode. If we denote by p and P R the probabilities of an error occurring during the transmission of one bit of information (Bit Error Rate, or BER) and a block of length n bits, respectively, then P R - 1 - (1 - p) p . Then the average number N of block transmissions before its successful transmission (transmission of the block without errors) and the effective data transfer rate C in the channel with the capacity C are determined by the formulas:
N = У kP R kl (lP R ) = „ 1
S (1-P R ) 2 'c = C (1 - P R ) 2 .
To ensure no more than 20% decrease in channel performance, it is necessary that the probability p satisfies the relation pn <0.1 (obviously, in this case, P R ~ pn). When p <10 3 bits, we get p <10 " 4 .
Above, in the calculations, it was assumed that any error in a block of length n bits can be detected using the extended Hamming code, which in practice corresponds to reality with probabilities p <10 4 .
Obviously, the error probability p is determined by the signal-to-noise ratio (the ratio of the signal power to the noise power at the signal receiving point). Below is a typical graph of the dependence of the error probability per sign of the transmitted information on the signal-to-noise ratio for the case of amplitude modulation with several signal levels (Fig. 7.8).
In the graph, the signal-to-noise ratio (SNR) is expressed in decibels and is determined by the formula SNR = 201og JO of the signal power and noise at the point of signal reception. In the case of the ISO 14443 standard, two-level amplitude modulation is used, which means that the signal-to-noise ratio must be at least 8 decibels.
where S and N are respectively
Obviously, in order for the reader and the card to be functionally and physically compatible, satisfying the ISO 14443 standard, it is necessary to define a certain minimum set of tests for compliance with this
Rice. 7.8. Graph of the dependence of the error probability per sign of the transmitted information on the signal-to-noise ratio for the case of amplitude modulation with several signal levels
standard. This set of ISO 14443 compliance tests for card and reader is defined in ISO 10373-6.
However, the ISO 14443 specification in its original form cannot be used for organizing cashless payments using contactless cards. This is due to a number of reasons listed below. As a result, the MasterCard payment system proposed the MasterCard PayPass ISO 14443 Implementation Specification, which was supported by the VISA and JCB payment systems. As a result, in August 2007, the EMV Contactless Communication Protocol specification appeared on its basis, the rights to which were received by EMVCo. EMVCo also ensures the development of this standard. Today, the EMV Contactless Communication Protocol version 2.0 specification is used. EMVCo has developed Type Approval Level 1 testing procedures for EMV Contactless Communication Protocol version 2.0.
The EMV Contactless Communication Protocol specification clarifies the ISO 14443 standard.
First, it is unacceptable for payment applications when there are several contactless cards in the working area of the reader. Indeed, in this case, in accordance with ISO 14443, the choice of the card for working with the terminal is determined by anti-collision procedures, and not by the card holder. The card selected by the terminal and the application on it are determined only at the beginning of the operation. Even if all cards in the working area of the reader belong to one holder, the latter has the right and must know which of his cards will be used for payment. Therefore, in accordance with the EMV Contactless Communication Protocol specification, if several cards are present in the reader's field, the transaction will not be performed. A warning about the presence of several cards in the working area of the terminal will appear on the terminal screen, and the cashier will ask the holder to separate the card from the rest, which he is going to use. As a result, in this case there is no need for the terminal to implement the conflict resolution procedures provided for in the ISO 14443 standard.
The ISO 14443 standard formulates its requirements for both the card and the reader. This allows for ambiguous interpretation of a number of its provisions, which inevitably leads to incompatibility between readers and cards supplied by different manufacturers. To remedy the situation, the EMV Contactless Communication Protocol specification formulates its provisions separately for the card and the terminal.
The EMV Contactless Communication Protocol specification also clarifies the requirements (formulated additional requirements) for the characteristics of the stability of the radio signal (frequency range, signal synchronization, duty cycle, rise & fall times), as well as for all parameters used in the standard, the permissible deviations are determined, which is extremely important to ensure compatibility products from various manufacturers.
The EMV Contactless Communication Protocol specification requires the terminal to support both types of cards (ISO 14443 Type A and ISO 14443 Type B), as well as modernize the polling procedure defined in ISO 14443 in order to take into account the possible presence of both types of cards in the reader's area ...
The EMV Contactless Communication Protocol specification formulates a requirement that defines the conditions that make it impossible to perform the next transaction on the card until the card is removed from the reader's working area.
The EMV Contactless Communication Protocol specification also defines the procedures for the correct termination of the dialogue between the card and the reader in the case when this dialogue was interrupted for some reason and the card was removed from the working area before the dialogue was completed. This procedure (exception handling) is very important for the correct completion of the financial transaction.
Finally, the EMV Contactless Communication Protocol specification defines:
- Part 1. Physical Characteristics.
- Part 2. Radio Frequency Power and signal interface.
- Part 3. Initialization and anti-collision.
- Part 4. Transmission protocols.
- card dimensions and physical characteristics of plastic, which must comply with ISO 7810 standards for ID-1 cards and ISO7816-1 for contact cards;
- bending and torsion tests that the card must pass successfully when tested;
- resistance to ultraviolet and x-ray radiation;
- the quality of the card surface required for printing on it;
- sensitivity to static and alternating electric and magnetic fields;
- temperature regime: from 0 to +50 ° C.
The second part of the standard (ISO 14443 - Part 2. Radio frequency characteristics and signal interface) defines the radio frequency characteristics of signals and signal interfaces (modulation and bit coding methods), including:
- frequency of the radio signal carrier - 13.56 MHz ± 7 KHz (22.1 m);
- the default modulation rate is 106 Kbaud, that is, during the transmission of a bit (Elementary Time Unit = 9.4395 μs), the carrier performs 128 full oscillations;
- two types of signal interfaces in forward (reader - * card) and reverse (card - * reader) channels - Type A and Type B;
- using a subcarrier with a frequency of 847.5 kHz (1/16 of the carrier frequency) for modulating the signal in the return channel. As a result, during the transmission of a bit, the subcarrier makes 8 complete oscillations.
- water, human body, grease and other dirt are transparent to high frequency waves;
- metal is an obstacle to the propagation of waves in the HF range.
The 13.56 MHz carrier belongs to the frequency range known as the “ISM frequency” (Industrial, scientific and medical equipment). It does not interfere with industrial emissions, provides a high data transfer rate (in the order of 10 Mbit / s), as well as the ability to implement an LC circuit on the card with a frequency within 12-18 MHz.
To transmit digital information from the reader to the card, the method of amplitude modulation (ASK modulation) is used. There are two most common varieties of ISO 14443: Type A and Type B. ISO 14443 Type A uses 100% ASK modulation and a modified Miller code, in which the transmitted signal level most of the time takes the highest value and drops to zero at very short time (2-3 µs) in the first half of the bit time when transmitting bit “0” or in the second half of transmitting a bit when transmitting bit “1”. In addition, when sequential bits' G and '0' are transmitted one after another, the pause when encoding the '0' bit is not used to reduce the signal spectrum width. This also increases the accumulation of energy by the card from the reader signal (on the capacitor,
ISO 14443 Type B uses the 10% ASK modulation method and NRZ code, in which the carrier amplitude reaches its maximum value for the transmission of a binary '1', and the amplitude of the radio signal is reduced to about 81.8% of the signal level during the transmission of '0' used when transmitting bit '1'. Thus, using the ISO 14443 Touré B standard, the card is constantly “charged” with energy.
To transfer data from the card to the reader, a load modulation method is used. Its essence lies in the use of the so-called load resistance, which can be included in the circuit of the resonant circuit of the microcircuit and excluded from it. Turning on / off the load resistance to / from the circuit leads to a change in the characteristics of the resonant circuit of the microcircuit, and hence the value of the amplitude of the field generated by it. Since the resonant circuits of the reader and the microcircuit form a transformer connection, this field change is reflected in the performance of the reader and can be measured on the reader side by, for example, measuring the current in the reader's antenna.
Turning on / off the load resistance, obviously, can be "tied" to the signal transmission from the card to the reader. The return channel signal (from the card to the reader), generated using the load modulation method, can be modulated on a subcarrier with a frequency of 847.5 kHz. In this case, if A is the current level of the transmitted signal, ω and O are the cyclic frequencies of the carrier and subcarrier, respectively, then the signal level Z (t) at time t is represented by the expression:
Z (t) = A (1 + m • cos O • t) • coscot =
- A cos cot + - ^ - cos (co + Q) t 4- ^^ - cos (co - Q) t.
In the return channel of the ISO 14443 Type A standard, the Manchester code is used to encode the signal, in which the information bit is encoded with a discrete signal, which is a step function. To represent the 'G bit, the first half of the rung takes the minimum constant value, and the second - the maximum value. Conversely, bit '0' is represented by a rung, the first half of which is at the maximum constant value and the second half is at the minimum value.
To transmit the Manchester encoded signal in the return channel, the load modulation with the subcarrier used in the On-Off Keying mode is used. The latter means that the load modulation is "turned on" to transmit the low level of the Manchester code step (Fig. 7.6). In the figure, PCD stands for Reader and PICC stands for Proximity Card.
In the ISO 14443 Type B return channel, the bits are encoded using the already mentioned NRZ code. Load modulation is used to generate the transmitted signal. To transmit the signal, phase modulation of the signal from the subcarrier is used (see Fig. 7.6).
Let us now dwell on one common myth, which is that ISO 14443 Type B cards, due to the 10% amplitude modulation method used in them, are energetically much more efficient (they get more energy from the reader's radiation) in comparison with ISO 14443 Type B cards. A. Indeed, the ISO 14443 Type A map uses a modified Miller code in the forward link. The bit time for a transmission rate of 106 kbps is approximately 9.4395 µs. During the transmission of a bit when using the Mil-
Rice. 7.6. ISO 14443 forward and reverse waveform
The pause, during which the reader does not transmit a signal to the card, takes about 2-3 microseconds. For calculations, we will assume that the pause is 30% of the transmission time of a bit of information. Since when the sequence of bits '1', '0' appears, the pause is not used at all, but in all other cases it is used, it is easy to obtain that the average signal power received by the card during the data transmission by the reader is 3 1
067A • + A • -4- = 0.775 • A, where A is the power of the signal received
card during carrier transmission.
ISO 14443 Type B charts use NRZ code and 10% amplitude modulation. Since the signal power is proportional to the square of its amplitude, the average power of the modulated signal received by the card during data transmission by the reader is in this case (0.818) 2 • A • y + A • y = 0.835 • A.
From this we can draw the following conclusion: ISO 14443 Type B cards with the same parameters of the transmitter and reader antenna allow you to receive about 7% more energy than ISO 14443 Type A cards during data transfer from the reader to the card.
However, as the measurements of Gemalto specialists show (Fig. 7.7), the transfer of data from the reader to the card accounts for less than 15% of the total time spent by the contactless card in the working area of the reader. The rest of the time, the card receives the reader's carrier signal, which is independent of the card type. It follows that the gain in the average signal power received by the ISO 14443 Type B card from the reader during the processing of the operation does not exceed 1%!
The third part of the ISO 14443 protocol (ISO 14443 - Part 3. Initialization and anti-collision procedures) defines:
• card initialization procedures: procedures for polling cards by a reader, selecting a card for operation, as well as formats used for polling and selecting commands;
Contactless Contact
Transaction Transaction
Rice. 7.7. Transaction processing time via contact and contactless card interfaces
• procedures for resolving possible conflicts between several contactless cards located in the working area of the reader, competing for the right to work with the reader. The procedures ensure that the reader operates with exactly one card at a time.
The ISO 14443 standard uses two widespread collision resolution methods - clocked ALOHA (for ISO 14443 Type B cards) and a tree-based search algorithm by chip ID (for ISO 14443 Type A cards).
Finally, the fourth part of the ISO 14443 standard (ISO 14443 - Part 4. Data transfer protocol) defines a high-level half-duplex block protocol for transferring data between the card and the reader (T = CL), similar to the T = 1 protocol. The protocol defines the encapsulation of data, the format of data blocks, procedures for dividing data into blocks, procedures for detecting errors (ISO / IEC 13239) and recovering corrupted data. The T = CL protocol provides support for ISO 7816-4 packet exchange (APDUs) and application selection procedure (ISO 7816-5), making it easy to use the same application in both contactless and contact modes.
The ISO 14443 standard defines the value of the data transfer rate between the reader and the card equal to 106 Kbps. At the same time, transmission rates of 212 Kbps, 424 Kbps and 848 Kbps are technically available today. The issue of using speeds above 848 Kbps is being actively discussed. At the same time, in practice, for reasons of energy saving of the contactless card microcircuit, the speed of 106 Kbps is most often used.
In the ISO 14443 standard, to ensure the protection of transmitted data from errors, an error-correcting coding algorithm is used, as defined in the ISO / IEC 13239 standard. The algorithm is based on the extended cyclic Hamming code, given by the generating polynomial g (x) = x 16 4- x 12 + x 5 + 1 (this means that the check sequence generated by the code is 2 bytes in size).
It is easy to prove that the code distance (the minimum Hamming distance between any two different codewords) of this cyclic code is 4 (the minimum weight (number of ones) of a nonzero codeword is 4). It follows that the code used is able to reliably detect in the received data block any single, double errors, as well as any errors of odd multiplicity.
It is not guaranteed that the code is capable of detecting other group errors as well. The ability of the code to correct any errors of odd multiplicity follows from the fact that, obviously, all codewords of the code under consideration have an even weight.
Extended Hamming is used in the ISO 14443 standard in error detection mode. If we denote by p and P R the probabilities of an error occurring during the transmission of one bit of information (Bit Error Rate, or BER) and a block of length n bits, respectively, then P R - 1 - (1 - p) p . Then the average number N of block transmissions before its successful transmission (transmission of the block without errors) and the effective data transfer rate C in the channel with the capacity C are determined by the formulas:
N = У kP R kl (lP R ) = „ 1
S (1-P R ) 2 'c = C (1 - P R ) 2 .
To ensure no more than 20% decrease in channel performance, it is necessary that the probability p satisfies the relation pn <0.1 (obviously, in this case, P R ~ pn). When p <10 3 bits, we get p <10 " 4 .
Above, in the calculations, it was assumed that any error in a block of length n bits can be detected using the extended Hamming code, which in practice corresponds to reality with probabilities p <10 4 .
Obviously, the error probability p is determined by the signal-to-noise ratio (the ratio of the signal power to the noise power at the signal receiving point). Below is a typical graph of the dependence of the error probability per sign of the transmitted information on the signal-to-noise ratio for the case of amplitude modulation with several signal levels (Fig. 7.8).
In the graph, the signal-to-noise ratio (SNR) is expressed in decibels and is determined by the formula SNR = 201og JO of the signal power and noise at the point of signal reception. In the case of the ISO 14443 standard, two-level amplitude modulation is used, which means that the signal-to-noise ratio must be at least 8 decibels.
where S and N are respectively
Obviously, in order for the reader and the card to be functionally and physically compatible, satisfying the ISO 14443 standard, it is necessary to define a certain minimum set of tests for compliance with this
Rice. 7.8. Graph of the dependence of the error probability per sign of the transmitted information on the signal-to-noise ratio for the case of amplitude modulation with several signal levels
standard. This set of ISO 14443 compliance tests for card and reader is defined in ISO 10373-6.
However, the ISO 14443 specification in its original form cannot be used for organizing cashless payments using contactless cards. This is due to a number of reasons listed below. As a result, the MasterCard payment system proposed the MasterCard PayPass ISO 14443 Implementation Specification, which was supported by the VISA and JCB payment systems. As a result, in August 2007, the EMV Contactless Communication Protocol specification appeared on its basis, the rights to which were received by EMVCo. EMVCo also ensures the development of this standard. Today, the EMV Contactless Communication Protocol version 2.0 specification is used. EMVCo has developed Type Approval Level 1 testing procedures for EMV Contactless Communication Protocol version 2.0.
The EMV Contactless Communication Protocol specification clarifies the ISO 14443 standard.
First, it is unacceptable for payment applications when there are several contactless cards in the working area of the reader. Indeed, in this case, in accordance with ISO 14443, the choice of the card for working with the terminal is determined by anti-collision procedures, and not by the card holder. The card selected by the terminal and the application on it are determined only at the beginning of the operation. Even if all cards in the working area of the reader belong to one holder, the latter has the right and must know which of his cards will be used for payment. Therefore, in accordance with the EMV Contactless Communication Protocol specification, if several cards are present in the reader's field, the transaction will not be performed. A warning about the presence of several cards in the working area of the terminal will appear on the terminal screen, and the cashier will ask the holder to separate the card from the rest, which he is going to use. As a result, in this case there is no need for the terminal to implement the conflict resolution procedures provided for in the ISO 14443 standard.
The ISO 14443 standard formulates its requirements for both the card and the reader. This allows for ambiguous interpretation of a number of its provisions, which inevitably leads to incompatibility between readers and cards supplied by different manufacturers. To remedy the situation, the EMV Contactless Communication Protocol specification formulates its provisions separately for the card and the terminal.
The EMV Contactless Communication Protocol specification also clarifies the requirements (formulated additional requirements) for the characteristics of the stability of the radio signal (frequency range, signal synchronization, duty cycle, rise & fall times), as well as for all parameters used in the standard, the permissible deviations are determined, which is extremely important to ensure compatibility products from various manufacturers.
The EMV Contactless Communication Protocol specification requires the terminal to support both types of cards (ISO 14443 Type A and ISO 14443 Type B), as well as modernize the polling procedure defined in ISO 14443 in order to take into account the possible presence of both types of cards in the reader's area ...
The EMV Contactless Communication Protocol specification formulates a requirement that defines the conditions that make it impossible to perform the next transaction on the card until the card is removed from the reader's working area.
The EMV Contactless Communication Protocol specification also defines the procedures for the correct termination of the dialogue between the card and the reader in the case when this dialogue was interrupted for some reason and the card was removed from the working area before the dialogue was completed. This procedure (exception handling) is very important for the correct completion of the financial transaction.
Finally, the EMV Contactless Communication Protocol specification defines:
- the minimum working area of the reader (operating volume) and its position in relation to the terminal (landing plane);
- data exchange rates: the card and the terminal must support the speed of 106 Kbps; the card does not need to support other baud rates, but the terminal can support 212 Kbps and 424 Kbps.
