Rf620R/Rf630R - Siemens SIMATIC RF600 System Manual

Dense Reader Mode (DRM)
In this mode, tag readability is increased through the application of interference-reducing
measures.
DRM is only defined for Gen 2 and does not function with other tag types.
Operating principle
Dense Reader Mode allows physically adjacent readers to use the same frequency when Gen
2 tags are being used.
In accordance with EPC Global as well as ETSI EN 302 208 V1.2.1, the four transmit channels
are used for transmission with the RF670R, with the RF660R in Firmware Version V1.3 and
higher, and with the RF620R/RF630R (see Section Regulations for UHF frequency bands in
Europe (ETSI EN 302 208 V1.2.1) (Page 54)) and the tag response appears on the
associated neighboring channels. As a result of the large difference in level between the
transmitter channels and the tag response channels, this technology provides great
advantages for frequency reuse. However, a prerequisite is that a certain minimum distance,
and thus minimum decoupling, is observed between the antennas of adjacent readers.
In accordance with EPC Global as well as ETSI EN 302 208 V1.1.1, only the even channels
are used for transmitting in this mode (communications path Reader -> Tag) with the RF660R
in Firmware Version V1.2 and below; the tag response is on the odd channels as a result of
the frequency offset.
Antenna alignment and distances
The minimum distance required between antennas that use the same frequency and that are
connected to different readers depends on the maximum radiated power set (RF670R with
SIMATIC RF600
System Manual, 06/2010, J31069-D0171-U001-A10-7618
Draft Version 02.06.2010
RF600 system planning
4.3 Antenna configurations
47