Listen Before Talk; Environmental Conditions For Transponders/Tags; Basic Rules; The Response Of Electromagnetic Waves In The Uhf Band - Siemens SIMATIC RF600 System Manual

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 57) and Chapter Regulations for UHF frequency bands in Europe (ETSI EN 302 208
V1.2.1) (Page 54) ).
4.4

Environmental conditions for transponders/tags

4.4.1

Basic rules

The transponder/tag must not be placed directly on metal surfaces or on containers of liquid.
For physical reasons, a minimum distance must be maintained between the tag antenna and
conductive material. A minimum distance of 5 cm is recommended. The tag operates better
when the distance is greater (between 5 and 20 cm).
● Tag assembly on non-conductive material (plastic, wood) has a tendency to be less critical
than assembly even on poorly conductive material.
● The best results are achieved on the materials specified by the tag manufacturer.
● You can obtain more detailed information from the tag manufacturer.
4.5

The response of electromagnetic waves in the UHF band

4.5.1

The effect of reflections and interference

Reflections and interference
Electromagnetic waves in the UHF band behave and propagate in a similar manner to light
waves, that is they are reflected from large objects such as ceilings, floors, walls and windows
and interfere with each other. Due to the nature of electromagnetic waves, interference can
lead to wave amplification which can produce an increased reading range. In the worst case,
SIMATIC RF600
System Manual, 06/2010, J31069-D0171-U001-A10-7618
4.5 The response of electromagnetic waves in the UHF band
Draft Version 02.06.2010
RF600 system planning
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