WTS User Guide V05 Page - 5 -
5. RF Communication.
5.1 Overview.
5.1.1 RF Frequency
The system is configurable for being used in 868MHz, 902MHz or 920MHz frequency bands. As a
general guideline, 868MHz is dedicated to Europe when 902 and 920MHz are dedicated to
Americas and Asia-Pacific. Both master box and slave sensor uses RF transceivers that are suited
for systems targeting compliance with EN 300 220 (Europe) and FCC CFR Part 15 (US).
Nevertheless, approval for the finished product is not yet performed. Therefore, prior to use the
system in any country, we do recommend checking for local regulation.
RF Frequency can be set by end user on master side (please refer to master specification sheet).
Whatever the RF frequency is, any slave will be able to synchronize by scanning automatically all
bands without any configuration change.
5.1.2 RF pairing
When delivering a system, we provide a master box paired with up to 22 slave sensors. The
pairing mechanism is based on 3 parameters:
•Customer ID: this ID is factory set and cannot be changed by the end user. This prevents
from any interference between end users.
•System ID: this is the ID of a whole system including one master and up to 22 slaves. The
system ID must be the same for the master and all its slaves. So special care must be
taken regarding this parameter. In fact, using a same system ID for 2 different systems
will result in interferences between the 2 systems. The end user can use simultaneously
up to 16 different systems.
•Slave ID: This ID is dedicated to discriminate and identify the slaves. The end user can
use simultaneously up to 22 slaves. Depending on CAN data frequency used, this number
can be reduced (please refer to configuration section).
5.1.3 RF anti-collision mechanism
In order to deal with several systems in the same area, the system uses a channel jump
mechanism. There are 5 channels shared with 3 different channel jump sequences.
The channel jump sequence can be configured by the end user (please refer to configuration
section). In order for a team to get several cars communicating easily in the same box, we
recommend:
- to have a different channel jump sequence for each car.
- to have the same channel jump sequence for a whole system (a master and its paired
slaves would have the same channel jump sequence).
Note: About channel jump sequence, we can advise customer regarding the best option to choose
when ordering the system, depending on its application.
