Frequency Hopping; Listen Before Talk - Siemens SIMATIC RF600 System Manual

4.3.7.4

Frequency hopping

This technique should prevent mutual interference between readers. The reader changes its
transmission channel in a random or programmed sequence (FHSS).
Procedure for FCC
The 50 available channels mean that the probability is low that two readers will be operating
on the same frequency (see Section Regulations for UHF frequency bands in the USA
(Page 66)). In China, one reader operates on at least 2 channels, e.g. 16 channels of 2 W
(see Section Regulations for UHF frequency bands in China (Page 68)).
Procedure for ETSI
Frequency hopping is optional here. According to ETSI EN 203 208 V1.2.1, frequency
hopping is however recommended to ensure that the reader does not have to pause for 100
ms after 4 seconds.
4.3.7.5

Listen before talk

With this technique which is only applicable to ETSI, the reader checks whether the relevant
channel is assigned before transmission to prevent collisions. The reader will only transmit
when this channel is free. The reader can transmit for up to 4 seconds on this channel and
must then either pause for at least 100 milliseconds or jump immediately to an unassigned
channel where it can transmit for another 4 seconds.
With the new ETSI EN 302 208 standard V1.2.1 this technique must be not be used (see
Chapter Regulations for UHF frequency bands in Europe (ETSI EN 302 208 V1.1.2)
(Page 60) and Chapter Regulations for UHF frequency bands in Europe (ETSI EN 302 208
V1.2.1) (Page 62) ).
SIMATIC RF600
System Manual, 10/2009, J31069-D0171-U001-A8-7618
RF600 system planning
4.3 Antenna configurations
55