Standardisation - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 257

U mess

L

C3

R1

Figure 9.38 Circuit of a reference card for testing the power supply of a contactless smart
card from the magnetic HF field of a reader

Power supply and modulation With the aid of a defined reference card it
is possible to test whether the magnetic field generated by the reader can provide
sufficient energy for the operation of a contactless smart card. The principal circuit of
such a reference card is shown in Figure 9.38. This consists primarily of a transponder
resonant circuit with adjustable resonant frequency, a bridge rectifier, and a set of load
resistors for the simulation of the data carrier.
To carry out the test, the reference card is brought within the interrogation zone of
a reader (the spatial characteristics of the reader's interrogation field are defined by
the manufacturer of this device and should be known at the start of the measurement).
The output voltage U meas of the reference card is now measured at defined resonant
frequencies ( f res = 13-19MHz) and load resistances (910 , 1800 ) of the reference
card. The test has been passed if the voltage within the interrogation zone does not
fall below a lower limit value of 3 V.
Loadmodulation A second reference card can be used to provide a test procedure
that makes it possible to test the adherence of the receiver in the reader to a minimum
necessary sensitivity. The circuit of this test card largely corresponds with the circuit
from Figure 9.38, but it has an additional load modulator.
To carry out the test, this reference card is brought into the interrogation zone of a
reader, this interrogation zone being defined by the manufacturer. The reference card
thus begins to transmit a continuous subcarrier signal (847 kHz in accordance with ISO
14443) by load modulation to the reader and this signal should be recognised by the
reader within a defined interrogation zone. The reader under test ideally possesses a
test mode for this purpose, in which the operator can be alerted to the detection of a
continuous subcarrier signal.

9.2.4.3 Part 7: Test procedure for vicinity coupling
smart cards

This part of the standard describes test procedures for the functional testing of the
physical interface between contactless smart cards and readers in accordance with ISO
15693-2. The test equipment and testing procedure for this largely correspond with the
testing equipment defined in Part 6. The only differences are the different subcarrier
frequencies in the layout of the reference card (simulation of load modulation) and the
different field strengths in operation.