HME DX100 EU, Operating Instructions Manual

Page: 29 / 34

24
APPENDIX A: EU BASE STATION ADAPTIVE FREQUENCY
HOPPING
Hereby, HM Electronics, Inc., declares that DX100 is in compliance with the essential requirements and other
relevant provisions of Radio Equipment Directive (RED). In AFH mode, DX100 complies with European
Telecommunications Standards Institute (ETSI) harmonized European standard EN 300 238. Customers,
Distributors or Installers operating in a CE regulated country that switch off or disable AFH will render the
product non-compliant with the directive and will be considered a manufacturer of the product.
CE Base Station Adaptive Frequency Hopping - Background
The DX100 wireless system utilizes a Frequency Hopping Spread Spectrum (FHSS) radio in order to provide
robust communications. This system operates in the unlicensed 2.4 GHz band. With the proliferation of other
devices over the past few years in the same 2.4 GHz band, instances where these devices and systems can
interfere with each other has greatly increased. The European Union has updated the radio standards for
equipment operating in this 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 300 328.
Adaptive Frequency Hopping
In order to reduce interference with other equipment and comply with ETSI Regulations, 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, unoccupied 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 channels.
The system 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.
Operation in Severe Environments
During normal operation, the fact that the system is constantly changing the channel list in use is transparent to
the user. It is possible, however, that in an environment with severe interference that the system may experience
a slight degradation. The Clear-Com system will use a minimum of 15 channels. If the environment is very
crowded and less than 15 channels are truly available, there could be increased radio ‘packet loss’ due to the
high interference. The following symptoms may be observed with AFH systems in a highly congested radio
environment:

This may result in system ‘busy’ indications. Channel lists are updated every few seconds, and in a
severe environment it is possible that these lists get missed by the communicator.

Slight degradation in audio fidelity between the headsets and base station. This would be due to the
same symptom as the ‘busy’ indications. The HD audio processing is tolerant to this condition, which
is why the degradation may only be slight.

Longer times to register. Registration may take longer, since the headset has to acquire the channel list
from the base station. If the base station has excluded a lot of channels, this takes longer as the
communicator does not have the exclusion list and looks for the base on channels it is not using.

Initial sync time increase. For the same reason registration may take longer, the initial headset sync on
power up may take longer.
EU Bases are shipped in the AFH (E-mode)
Do not tamper with the AFH mode if you are operating in a region that requires compliance with ETSI
EN300 328. Changes and modifications not expressly approved by Clear-Com, LLC an HM
Electronics, Inc. company could void the user’s authority to operate this equipment.