Standardisation - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 264

Table 9.18 Provisional technical parameters of a GTAG reader

Parameter Value

Transmission frequency and power of the
reader

862-928MHz, 2-4W (depending upon
regulations)

Downlink 40% ASK Pulse Time Modulation, '1 of $'

coding

Anticollision procedure Dynamic slotted ALOHA procedure

Maximum number of transponders in the field 250

Table 9.19 Provisional technical parameters of a GTAG transponder

Parameter Value

Minimum frequency range of transponder 862-928MHz

Uplink Backscatter (Delta RCS), bi-phase code

Bit rate Slow: 10Kbit/s, fast: 40Kbit/s

Delta RCS > 0.005m 2

the case of backscatter transponders whether the reader uses a fixed transmission fre-
quency (Europe) or changes the transmission frequency at periodic intervals ( frequency
hopping spread spectrum , USA and Canada).

9.6.2.2 GTAGcommunicationandapplication layer

The GTAG communication and application layers are described in the MP&PR speci-
fication (minimum protocol and performance requirement). The MP&PR (GTAG-RP)
defines the coding of data on the contactless transmission path, the construction of a
communication relationship between reader and transponder (anticollision and polling),
the memory organisation of a transponder, and numerous commands for the effective
reading and writing of the transponder.
The memory of a GTAG transponder is organised into blocks each of 128 bits
(16 bytes). The GTAG specification initially permits only the addressing of a maximum
of 32 pages, so that a maximum of 512 bytes can be addressed. However, it should be
assumed that for most applications it is sufficient for a data set identical to the barcode
in accordance with EAN/UCC-128 to be stored in a page of the transponder.