Document Version 1.2
Last revised on
2017-09-26
Page 14 of 92
Reference Manual for uTrust 4701F and uTrust 4711F Readers
3.6.
Contactless communication principles and uTrust 47xx F usage
recommendations
uTrust 47xx F is a dual interface reader capable of reading both contact smart cards and contactless
user tokens. The following paragraph focuses on a few specifics of contactless communication to
outline usage recommendations in order to ensure best user experience.
uTrust 47xx F is a contactless reader
1
designed to communicate with user
credentials.
User credentials
2
are made of a contactless
integrated circuit chip connected to an
antenna
User credentials can take several form
factors:
●
Credit card sized smart card
●
Key fob
●
USB token
●
NFC mobile phone etc…
Communication between uTrust 47xx F and user credentials uses magnetic field inductive coupling.
The magnetic field generated by uTrust 47xx F has a carrier frequency of 13.56MHz.
3.6.1.
Power supply
When the user credential is put in the magnetic field of the reader, its antenna couples with the reader
and an induction current appears in the antenna thus providing power to the integrated circuit. The
generated current is proportional to the magnetic flux going through the antenna of the user
credential.
3.6.2.
Data exchange
The carrier frequency of the magnetic field is used as a fundamental clock signal for the
communication between the reader and the credential. It is also used as a fundamental clock input
for the integrated circuit microprocessor to function.
To send data to the user credential the reader modulates the amplitude of the field. There are several
amplitude modulation and data encoding rules defined in ISO/IEC 14443. The reader should refer to
the standard for further details.
To answer the reader, the integrated circuit card of the user credential modulates its way of loading
(impedance) the field generated by the reader. Here also further details can be found in ISO/IEC 14443.
1
In the ISO/IEC 14443 standard, the reader is called the proximity coupling device (PCD)
2
In the ISO/IEC 14443 standard, the user credential is called proximity integrated chip card (PICC)
User tokens
uTrust 47x1 F
