User's Guide

Web-based management Chapter 7: Operation
7-12
UNDER DEVELOPMENT
phn-2182_003v004 (Oct 2011)
Attribute Meaning
Link Loss The maximum, mean, minimum and latest measurements of Link
Loss (dB). See Diagnostics calculated over time on
page 7-23.
The link loss is the total attenuation of the wireless signal
between the two point-to-point units. The link loss calculation
presented below:
xxxx
RTRTll
ggPPP
+
+
−
=
Where:
ll
P
= Link Loss (dB)
x
T
P
= Transmit power of the remote wireless unit (dBm)
x
R
P
= Received signal power at the local unit (dBm)
xx
RT
gg ,
= Antenna gain at the remote and local units
respectively (dBi). The antenna gain of the ODU (23.5 dBi) is
used unless one or both of the units is a Connectorized
version.
For connectorized ODUs, the link loss calculation is modified to
allow for the increased antenna gains at each end of the link.
V/H Ratio The maximum, mean, minimum and latest measurements of V/H
Ratio. See Diagnostics calculated over time on
page 7-23.
This is calculated from:
Power received by the vertical antenna input (dB) ÷
Power received by the horizontal antenna input (dB)
V/H Ratio is an aid to debugging a link. If it has a large positive
or negative value, then investigate the following potential
problems:
An antenna coaxial lead may be disconnected.
When spatial diversity is employed, the antenna with the
lower value may be pointing in the wrong direction.
When a dual polar antenna is deployed, the antenna may be
directed using a side lobe rather than the main lobe.
When there is a reflection from water on the link and spatial
diversity is employed, then one expects large, slow swings in V/H
Ratio. This indicates the antenna system is doing exactly as
intended.