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EtherWave - WMR
7.0 Installation
Transmit Power
Having read thus far through the factors to be considered, it should
be clear that they are all interrelated. Transmit power should be set
for the minimum required to establish a reliable communications path
with adequate fade margin. Required transmit power is dictated pri-
marily by distance, antenna type (specifically the ‘gain’ of the anten-
nas being used), and the receive sensitivity of the distant Ether-
Wave-WMR. Cable and connector losses (the physical path from the
modem’s ‘antenna connector’ to the antenna’s connector) must also
be taken into account.
Receive Sensitivity
The EtherWave-WMR has exceptional receive sensitivity, which can
produce a number of benefits, such as: added fade margin for a
given link, being able to use less expensive coaxial cable or antenna
types, being able to operate at greater distances for a given distant
transmitter power (perhaps negating the requirement for a Repeater
site!). Distance, antenna gain, transmit power, and receive sensitiv-
ity are critical ‘numbers’ for radio path calculations. Fortunately, the
EtherWave-WMR features the maximum available transmit power
combined with exceptional receive sensitivity - two ‘numbers’ which
will produce the most favorable path calculation results.
Fade Margin
When all radio path numbers are being considered and hardware
assumptions are being made, another factor to consider is the ‘fade
margin’ of the overall system. the fade margin is the difference be-
tween the anticipated receive signal level and the minimum accept-
able receive level (receive sensitivity). Being that the EtherWave-
WMR performs to exacting specifications, the overall deployment
should be such that the modems may be utilized to their full potential
to provide a reliable and robust communications link. A typical de-
sired fade margin is in the order of 20dB, however oftentimes a 10dB
fade margin is acceptable.
