ATA559001-6DSY Atmel, ATA559001-6DSY Datasheet - Page 64

• Manufacturer Part Number: ATA559001-6DSY
• Description: RF Wireless Misc UHF (1k bit r/w anti-collision)
• Manufacturer: Atmel

Specifications of ATA559001-6DSY

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9. Return Link
9.1
64
Return Link Header
ATA5590
The return link is based on a synchronous communication style in combination with 2PSK-type
modulation to get maximum SNR and minimum BER values.
In synchronous mode, the tag backscatters the information regarding the bit information
between two notch signals. The coding style of the return link was determined (mod flags) during
the forward link. Therefore, the spectrum to be used can be adjusted by the return header.
As the backscattered signal is always very weak, the reader can tune the quality of the link by
observing and analyzing the reference signals backscattered in the return link header section.
The return link header is used for return link initialization, and for initialization of the full duplex
communication during anticollision and group selection (deterministic-arbitration part).
The return link is controlled by this return header. The return header is used to set the following
parameters for the communication style:
During anticollision and group-selection procedures, the header is additionally used for defining
timing references of priority symbols.
If a static modulation scheme (notch-locked NRZI) is used during the return link, the modulation
inside the return header can be used as a reference symbol for the modulation. Therefore, the
first symbol is modulated, and the second symbol is not modulated. During the 3rd and 4th sym-
bols, the tag backscatters the modulation scheme as received with the modulation control bits.
Different coding styles inside the header section:
The return header contains 4 symbols. The EOF definition which is based on timing information
in the return header is mandatory for each tag. The third symbol shall have the same timing as
the fourth symbol. The tag stores all length information of the return header so that it can decode
EOF.
• The timing information of the EOF symbol of the return link, plus
• Timing information used as reference timing during the return link modulation
4817C–RFID–03/07