User's Manual

6 Site Planning
88
6.2.2 PTP 600 Series Bridge PIDU Plus
Site Selection
When selecting a site for the PIDU Plus the following should be taken into consideration:
• Availability of a mains electricity supply
• Accessibility for viewing status indicators and pressing Recovery switch.
6.2.3 Path Loss Considerations
The path l
oss is the amount of attenuation the radio signal undergoes between the two ends
of the link. The path loss is the sum of the attenuation of the path if there were no obstacles in
the way (Free Space Path Loss), the attenuation caused by obstacles (Excess Path Loss)
and a margin to allow for possible fading of the radio signal (Fade Margin).
Equation 2 - Path Loss
capabilityseasonalfadeexcessspacefree
LLLLL
<
+
+
+
_
Where
spacefree
L
_
Free Space Path Loss (dB)
excess
L
Excess Path Loss (dB)
fade
L
Fade Margin Required (dB)
seasonal
L
Seasonal Fading (dB)
capability
L
Equipment Capability (dB)
6.2.4 Definitions
The equipment capability i
s given in Table 20 to Table 33. Each table gives Link Loss, Output
Powe
r and System Thresholds for PTP 600 Series Bridge in all modulation modes for all
available channel bandwidths. Adaptive Modulation will ensure that the highest throughput
that can be achieved instantaneously will be obtained taking account of propagation and
interference. The calculation of Equation 1 needs to be performed to judge whether a
parti
cular link can be installed. When the link has been installed, web pages provide
information about the link loss currently measured by the equipment both instantaneously and
averaged. The averaged value will require maximum seasonal fading to be added, and then
the radio reliability of the link can be computed.