5.8 GHz One Antenna Reflective Tag

CHR2244

Ref. : DSCHR2244QDG5053 - 22 Feb 05

11/16

Specifications subject to change without notice

Route Départementale 128 , B.P.46 - 91401 ORSAY Cedex - FRANCE

Tel.: +33 (0)1 69 33 03 08 - Fax : +33 (0)1 69 33 03 09

Application Information

General Transmission system

The transmission system is described as follows, the tag doesn’t generate any frequency :

Fo

F-AM

TRANSMIT

MODE

RECEIVE

MODE

RECEIVE

MODE

TRANSMIT

MODE

Fo

Fm

Fo

BEACON

TAG

DOWNLINK

figure 1a

UPLINK

figure 1b

BEACON

TAG

Figure 1 : Transmission system operating principle

Two modes of communication are implemented :

From beacon to tag (figure 1a) : the beacon is in transmit mode while the tag is in the receive

mode. The beacon sends an Amplitude Modulated (AM) RF signal to the tag. In figure 1a, F-AM is the

amplitude modulation frequency and F0 is the carrier.

From tag to beacon (figure 1b) : the beacon is in receive mode while the tag is in transmit mode.

The beacon sends a continuous wave (CW) RF signal to the tag, this signal is then mixed ( at tag level )

with the MOD input signal (Fm) thanks to a reflective mixer. The reflected signal is sent back to the beacon

and is demodulated thanks to an homodyne receiver.