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SB nº SB-86 : Load Modulation Sense (Spec Change)

v1.0 Specification Bulletins

Specification Bulletin No. 86 First Edition September 2011 Load Modulation Sense This specification bulletin clarifies the PCD requirements related to the PICC load modulation sense.

Effective Date

This specification bulletin is effective from November 2011, at which time any affected or new type approval testing will also come into effect.

Applicability

This specification bulletin applies to: Book D – EMV Contactless Communication Protocol, Version 2.1 – March 2011. (EMV Contactless Specifications for Payment Systems, EMV Contactless Communication Protocol Specification, Version 2.0.1 – July 2009.)

Related Documents

None

Description

This specification bulletin clarifies the definition of the PICC load modulation sense. Currently the specification describes the loaded state as a higher current flowing through the antenna of the PICC. Therefore, the voltage measured on the sense resistor of the EMV – TEST PCD would increase when the PICC is in the loaded state and therefore have a “positive” sense as illustrated below This specification update clarifies the specification in such a way that the PCD must support a “positive” and “negative” load modulation sense.

http://www.emvco.com/specifications.aspx.

Specification Change Notice

  • Change section 3.4.1 as follows:

3.4.1 Introduction [...] Switching a load on and off at this frequency creates the subcarrier. When the PICC is in the loaded state, a higher current will flow through the antenna of the PICC than in the case where the load is not switched on. This difference in current in the PICC antenna is sensed by the PCD. Switching a load on and off at this frequency creates the subcarrier causing a different current to flow through the antenna of the PICC when in the loaded state than when in the unloaded state (the unloaded state of the subcarrier is the stable state when the PICC is not sending bits). This difference in current in the PICC antenna is sensed by the PCD.

  • Correct Table 3.15 as follows: Table 3.15—Measurement of Modulation PICC to PCD (PCD Reception) Step # Step 1 Action Set up the EMV – TEST PCD for nominal power as specified in Annex B.2. Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Place the EMV – TEST PICC in position (r=0, ϕ=0, z=0, θ=0) of the Operating Volume of the EMV – TEST PCD. Configure the EMV – TEST PICC with non linear load. Connect a square wave generator to J2 of the EMV – TEST PICC with a frequency of 847 kHz (fc/16). Regulate in such a way that the square wave modulates the carrier with amplitude VS1,pp (peak to peak) with positive sense (where the loaded state causes an increase in the observed voltage) measured at J2 of the EMV – TEST PCD with the EMV – TEST CMR. Refer to Annex A.3 for the value of VS1,pp. Place the EMV – TEST PICC in the Operating Volume of the PCD in a position with 0 ≤ z ≤ 2 cm. Request the PCD to send a valid command to the EMV – TEST PICC by means of the PCD Test Environment as described in Annex B.4. Return a correct response by means of the EMV – TEST PICC and verify if the PCD functions properly. Perform the measurement for Type A and Type B. Place the EMV – TEST PICC in position (r=0, ϕ=0, z=2, θ=0) of the Operating Volume of the EMV – TEST PCD. Configure the EMV – TEST PICC with non linear load. Connect a square wave generator to J2 of the EMV – TEST PICC with a frequency of 847 kHz (fc/16). Regulate in such a way that the square wave modulates the carrier with amplitude VS2,pp (peak to peak) with positive sense measured at J2 of the EMV – TEST PCD with the EMV – TEST CMR. Refer to Annex A.3 for the value of VS2,pp. Place the EMV – TEST PICC in the Operating Volume of the PCD in a position with 2 &lt; z ≤ 4 cm. http://www.emvco.com/specifications.aspx. Step # Step 9 Step 10 Action Request the PCD to send a valid command to the EMV – TEST PICC by means of the PCD Test Environment as described in Annex B.4. Return a correct response by means of the EMV – TEST PICC and verify if the PCD functions properly. Perform the measurement for Type A and Type B. Repeat Steps 2 to 9 but in Steps 3 and 7 regulate the square wave generator connected to J2 of the EMV – TEST PICC in such a way that the square wave modulates the carrier with negative sense (where the loaded state causes a decrease in the observed voltage). &lt;&lt;< END of Bulletin >>> http://www.emvco.com/specifications.aspx.