User's Manual

FEATURES AND OPERATION
2-12
Part No. 001-4090-101/102
2.5.2.7 Forward Power
Approximate measure of transmit power. This is a 4-digit value in watts rounded to the
nearest tenth. Note that this is an approximate value that should be used for trend
monitoring only. It does not compare in accuracy with values obtained by a standard
wattmeter.
2.5.2.8 Interpreting Power Readings
The values returned are approximate and should not be regarded as an absolute indicator of
performance. For example, a unit that shows a forward power of .9 watt may actually
measure at .9 watt on a lab quality wattmeter. For this reason, these values should not be
used to indicate that a unit is out of spec or to compare one unit to another.
However, the values returned should be consistent for any given unit. If statistics are kept on
a unit per unit basis, changes in forward or reflected power can be monitored. The following
conditions are worthy of investigation.
1.Forward power output (in watts) drops or rises by more than 10% from its established value.
Reflected power remains low. This indicates that the transmitter may need alignment or that a compo-
nent may be in need of replacement.
2.Forward power output drops by more than 10% from its established value or reflected power shows
an increase. This indicates a possible antenna or feedline problem that affects SWR (Standing Wave
Ratio).
2.5.2.9 Reverse Power
Approximate measure of reverse (reflected) power. The value is returned differently for on-
line and offline diagnostics:
Online: The value returned is 0 if reverse power is within acceptable limits, 1 if reverse
power is too high. The threshold is set to approximately 1/3 of the forward power value.
Offline: Value is in watts to the nearest tenth. This value is intended as an indication of
antenna problems and will normally be used for trend monitoring. Ideally it should be close
to zero, but values up to about 15% of Forward Power may be encountered in properly
operating systems.
We recommend recording values following original installation for use as future reference.