138 Glossary TB7100 Installation and Operation Manual
© Tait Electronics Limited December 2005
U
unbalanced line An unbalanced line has one wire earthed. It is typically used for short 
connections, for example, between a base station and a repeater on the same 
site. The system interface identifies the wires of unbalanced lines with Rx 
audio output, Tx audio input, and Ground.
User Defined 
Settings
The User Defined Settings are settings in the programming application that 
are specific to the customers application. These are the only settings that 
need to be changed when configuring a TB7100 for operation.
user interface The user interface panel is an area at the front of the base station with 
buttons, LEDs and other controls that let you interact with the base station.
V
valid signal A valid signal is a signal that the receiver responds to by opening the receiver 
gate. A signal is valid for example when it is stronger than a minimum level 
and when it has the specified subtone.
visual indicator The term “visual indicator” refers to a visual cue the radio gives to provide 
feedback to the user. Visual indicators are used in combination with audible 
indicators. Visual indicators include LEDs and LCD display text.
VSWR Voltage Standing Wave Ratio (VSWR) is the ratio of the maximum peak 
voltage anywhere on the line to the minimum value anywhere on the line.  
A perfectly matched line has a VSWR of 1:1.  A high ratio indicates that the 
antenna subsystem is poorly matched.
W
Watchdog A watchdog circuit checks that the system is still responding.  If the system 
does not respond (because the firmware has locked up), the circuit resets the 
system.