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SB nº 101 : FDT tolerance (Spec Change)

v1.0 Specification Bulletins
Contactless

Specification Bulletin No. 101 First Edition February 2012 FDT tolerance This Specification Bulletin aligns ISO/IEC 14443 and EMV regarding FDT tolerance.

Effective Date

This specification bulletin is effective from November 2012 at which time any affected or new type approval testing will 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

There is currently a difference between ISO 14443 and EMV regarding the tolerance for FDT measurement. This specification bulletin aligns the EMV specification with ISO/IEC 14443. The EMV specification states: “The FDT tolerance is in the range of -0 to +t4. t4 is the time period in which the PICC must detect the end of the last lower level transmitted by the PCD (see Section 3.3.2).” Here t4 could be taken to mean the actual t4 of the PCD being used which could be anywhere from 0 to 0.44μs. In ISO/IEC 14443 it states “The measured FDT shall be between the value given in Table 2 and the value given in Table 2 + 0.4μs.”. This is always 0.4μs regardless of the PCD being used. Also in ISO/IEC 14443 there is a requirement for a PCD to accept a response -1/fc early “The PCD should accept a response with a FDT tolerance of –1/fc to (+0.4μs + 1/fc).” whereas the corresponding EMV test delays the response by the uncertainty of the test bench to correspond to the EMV specification: “FDT tolerance is in the range of -0 to +t4”.

Specification Change In section 4.8.1, change as follows: The FDT tolerance is in the range of -0 to +t4. t4 is the time period in which the PICC must detect the end of the last lower level transmitted by the PCD (see section 3.3.2). Requirements 4.19: FDTA,PICC PCD 4.8.1.1 Following the end of a PCD command, the PCD shall be able to receive the start of a PICC response at a time aligned to the grid as defined in Figure 4.14, Table 4.2, and Table 4.3 with a tolerance of -1/fC to 0.4μs+1/fC. PICC 4.8.1.2 The PICC shall align the first modulation edge within the start bit of a PICC response to the grid as defined in Figure 4.14, Table 4.2, and Table 4.3 with a tolerance of 0 to 0.44μs.