Avaya CS 1000, Fundamentals

Page: 35 / 270

Figure 10: Coverage and speech quality in an open environment.
Be aware that DECT is a digital communication system. It incorporates a “transmission errors
hiding” system. This means that it tries to hide the transmission errors. The results of this
mechanism are as follows:
• A small incidental transmission error is not noticeable in speech.
• A minor transmission error causes audible clicks during speech.
• A major transmission error causes the loss of speech.
The following factors effects the voice quality as well:
• Moving speed
The DECT techniques allow a maximum moving speed of 5 kilometers per hour (km/h).
Bear this in mind if your DECT system must cover an elevator.
• Metal Construction
In metal structures, reflection can negatively impact voice quality (clicks and interruptions
can occur) even if you are close to the DAP. This effect is made worse when the handset
is in motion.
For more information see Coverage calculation on page 36.
The required quality depends on the customer requirements and the environment. The
following are the various quality levels:
• Excellent and good
In business, office, and first aid environments, the excellent and good voice quality is
required to avoid dropped calls, inherent sounds, or pauses in important conversations.
Site planning
SIP DECT Fundamentals October 2012 35