The European Union has introduced new radio standards for equipment operating in the 2.4 GHz band in an attempt
to reduce interference between equipment from different manufacturers. This European Telecommunications Standards
Institute (ETSI) harmonized European standard is known as EN 300 238 v1.8.1.
Adaptive Frequency Hopping
In order to reduce interference with other equipment and comply with these new regulations, Clear-Com has implemented
an Adaptive Frequency Hopping (AFH) mode for the new DX EU base stations. The key idea behind AFH is using only
the good frequencies, or channels not occupied by other equipment. The system scans for other signals and avoids these
signals during operation. Since the radio environment is constantly changing, there is a continuous process of scanning
for used frequencies and updating the list of good / open channels.
The DX410 EU base station utilizes 46 discrete frequencies, or channels, within the 2.4 GHz spectrum in order to
communicate voice and data. The process of deciding which channels should be used is a 3-stage process. The process
includes scanning for occupied channels, the broadcast of a channel exclusion list and the use of the exclusion list. The
process is completed in three steps coexisting in time.
Below is the process is shown in Time. First, the system performs a channel scan to determine occupied channels. This
list is then broadcast to the communicator. The communicators and base station will use this list during period three.
The process is continuous, and as is illustrated below, the list could be constantly changing. Depending on the radio
environment, a maximum of 46 channels, and a minimum of 15 channels may be used by the system at any time.