SB nº 99 : Start and End of Sequence Clarification (Spec Change)

Specification Bulletin No. 99 First Edition March 2012 Start and End of Sequence Clarification This Specification Bulletin clarifies the definition of the Start and End of Type A and Type B Sequences.

Effective Date

This bulletin is effective from November 2012, at which time any affected or new type approval testing will also come into effect.

Applicability

This Specification Bulletin applies to:  EMV Contactless Specifications for Payment Systems, Book D – EMV Contactless Communication Protocol Specification, Version 2.1 – March 2011. Related Documents  None

Description

To guarantee correct measurement of Frame Delay Times, the Start of Sequence (SoS) and End of Sequence (EoS) have to be specified more precisely. This specification update bulletin defines the start and end of Type A and Type B Sequences more precisely, for both PICC and PCD.

Proposed Specification Changes 1. Section 1.7.3 Value of Parameters. Replace the existing text with: ‘Throughout the specification, symbols are used to identify parameters. The permitted values of the parameters are listed in Annex A and are written in Arial bold to distinguish them in the text. When used to define timings, frequencies, etc., it is the actual value that is intended. For example fc is the actual carrier frequency from the PCD.’ 2. Section 4.8.1 Frame Delay Time PCD → PICC Add the following below existing Figure 4.14: The end of the last lower level of a PCD command is the point where the rising edge of the last lower level of the signal envelope passes through the 5% threshold as shown in Figure 4.15. Figure 4.15: End of PCD Command – Type A The start of the SoF of the PICC response begins at the start of the first detectable edge of the modulation of the signal envelope. Figure 4.16 shows the starting point for positive modulation and Figure 4.17 for negative modulation.

Figure 4.16: Start of PICC Response (Positive Modulation) – Type A Figure 4.17: Start of PICC Response (Negative Modulation) – Type A For positive or negative modulation, when observed using the EMV-TEST PCD, the signal envelope may appear to be neither 100% positive nor 100% negative (mixed) in any proportion and start with either a positive or negative part cycle – see Figure 4.18. Figure 4.18: Start of PICC Response (Example of mixed modulation starting with a positive part cycle) – Type A

3. Section 4.8.1 Frame Delay Time PCD → PICC Add the following below existing Figure 4.15: Figure 4.20 indicates the end of the EoS of the PCD command. It is the point where the last modulation of the signal envelope passes through the 10% level of the Δ threshold (Δ is the difference between modulated and unmodulated signal levels). Figure 4.20: End of PCD Command – Type B The start of the SoS of the PICC response begins at the nominal position of the start of the first phase shifted subcarrier cycle.  For positive modulation and an initial phase of 0° (extended low phase change) the nominal position is defined as the point where the signal envelope of the preceding subcarrier cycle passes through the local minimum (as shown in Figure 4.21) plus the addition of 1/fs (or 16/fc).  For positive modulation and an initial phase of 180° (extended high phase change) the nominal position is defined as the point where the signal envelope of the preceding subcarrier cycle passes through the local maximum (as shown in Figure 4.22) plus the addition of 1/fs (or 16/fc).  For negative modulation and an initial phase of 0° (extended high phase change) the nominal position is defined as the point where the signal envelope of the preceding subcarrier cycle passes through the local maximum (as shown in Figure 4.22) plus the addition of 1/fs (or 16/fc).  For negative modulation and an initial phase of 180° (extended low phase change) the nominal position is defined as the point where the signal envelope of the preceding subcarrier cycle passes through the local minimum (as shown in Figure 4.21) plus the addition of 1/fs (or 16/fc).

Figure 4.21: Start of PICC Response (Extended Low Phase Change) – Type B Figure 4.22: Start of PICC Response (Extended High Phase Change) – Type B

4. Section 4.8.2 Frame Delay Time PICC → PCD Add the following below existing Figure 4.18: The end of the last subcarrier modulation transmitted by the PICC corresponds to the end of the last detectable edge of the modulation of the signal envelope. Figure 4.26 shows the end for positive modulation and Figure 4.27 for negative modulation. Figure 4.26: End of PICC Response (Positive Modulation) – Type A Figure 4.27: End of PICC Response (Negative Modulation) – Type A For positive or negative modulation, when observed using the EMV-TEST PCD, the signal envelope may appear to be neither 100% positive nor 100% negative (mixed) in any proportion and end with either a positive or negative part cycle – see Figure 4.28.

Figure 4.28: End of PICC Response (Example of mixed modulation ending with a negative part cycle) – Type A The start of the lower level of the SoF of a PCD command is the point where the falling edge of the signal envelope passes through the 90% threshold as shown in Figure 4.29. Figure 4.29: Start of PCD Command – Type A

5. Section 4.8.2 Frame Delay Time PICC → PCD Add the following below existing Figure 4.19: The start of the EoS of the PICC response begins at the nominal position of the start of the first phase shifted subcarrier cycle (of the EoS).  For extended low phase change the nominal position is defined as the point where the signal envelope of the preceding subcarrier cycle passes through the local minimum (as shown in Figure 4.31) plus the addition of 1/fs (or 16/fc).  For extended high phase change the nominal position is defined as the point where the signal envelope of the preceding subcarrier cycle passes through the local maximum (as shown in Figure 4.32) plus the addition of 1/fs (or 16/fc). Note that EoS is treated in isolation and there is no distinguishable difference between positive and negative modulation. Figure 4.31: End of PICC Response (Extended Low Phase Change) – Type B Figure 4.32: End of PICC Response (Extended High Phase Change) – Type B

The start of the SoS of a PCD command is when the first modulation of the signal envelope passes through the 90% level of the Δ threshold (Δ is the difference between modulated and unmodulated signal levels) as shown in Figure 4.33. Figure 4.33: Start of PCD Command – Type B