User Guide

Link planning Planning considerations
2-16
pmp-0047 (December 2012)
Product Parameter
Range Details
2x 4x 6x
Max. NLOS2
Link Budget
(additional 25
dB link loss)
km
with LENS that adds 5.5 dB
to SM Range 1 mi / 1.6 km 0.4 mi / 0.6 km 0.1 mi / 0.2 km
with Reflector Dish that
adds 14 dB to SM Range 2.7 mi / 4.3 km 1 mi / 1.7 km 0.4 mi / 0.6 km
Path loss considerations
Path loss is the amount of attenuation the radio signal undergoes between the two ends of the link.
Calculating path loss
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). The following calculation needs to be performed to judge whether a particular link can be installed:
capabilityseasonal
fadeexcessspacefree
LLLLL <+++
_
Where: Is:
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)
Calculating maximum power level for connectorized AP units
If a connectorized PMP 450 AP is to be installed in a country that imposes an EIRP limit in the selected band,
calculate the highest setting of Maximum Power Level that will be permitted using this formula:
Maximum Power Level (dBm) = Allowed EIRP (dBm) – Antenna Gain (dBi) + Cable Loss (dB)
Where: Is:
Maximum Power
Level (dBm)
the highest permissible setting of the transmitter
output power,