Description varix 200/varix 14 (DECT)
2 - 9
2 Planning a cordless communications network
Are there any other DECT systems installed on the site or in the
immediate vicinity?
DECT systems are designed in a way which generally allows
other systems to operate nearby, although the ability to sustain
maximum telephone traffic levels will decrease in the case of
both systems. In order for radio cells to not adversely affect
each other, a minimum safety distance of the six-fold radius
2)
should be adhered to. Only at this distance will the field
strength have decreased to a level allowing identical frequen-
cies and time slots to be used.
As the other system will not operate synchronously to the varix,
every time slot used by the other system within the area com-
monly accessed by both systems can have the effect of prevent-
ing two slots being used in the new system. The affected areas
should be indicated in the footprint plans, as the level of tele-
phone traffic here cannot be assessed.
How large is the cell radius measured in the middle of the
area?
If the area under inspection is relatively homogeneous, then
one measurement will suffice. Transmission quality will deterio-
rate for attenuation up to -58 dBm (corresponds to display val-
ues between 7 and 8), connections will be cut off as if the
attenuation is -68 dBm (corresponds to display values between
0 and 6).
Transmission quality should be monitored continuously as meas-
uring takes place. Effects resulting from bit-error rates can be
monitored by checking the test sound.
1) This figure is presumed, as to date no previous values are known. Once such values have been established, then
the figure should be adjusted accordingly.
2) This value really only applies in the open. Walls and other objects attenuate the field strength of other DECT systems
on the site so that the region within which the two systems affect each other’s operation may be smaller.
