Readers - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 302

Control
(signal coding
protocol)

Application control commands Data

carrier

Application
(computer with
software
application)

Received
data

Transmitted
data

HF
interface

Antenna

Figure 11.2 Block diagram of a reader consisting of control system and HF interface. The
entire system is controlled by an external application via control commands

Figure 11.3 Example of a reader. The two functional blocks, HF interface and control system,
can be clearly differentiated (MIFARE reader, reproduced by permission of Philips Electron-
ics N.V.)

11.2.1 HF interface

The reader's HF interface performs the following functions:

• generation of high frequency transmission power to activate the transponder and

supply it with power;

• modulation of the transmission signal to send data to the transponder;

• reception and demodulation of HF signals transmitted by a transponder.

The HF interface contains two separate signal paths to correspond with the two
directions of data flow from and to the transponder (Figure 11.4). Data transmitted to