Tait TB9100, Installation And Operation Manual

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144Glossary
TB9100 Installation and Operation Manual
© Tait Electronics Limited May 2006
UTC
Coordinated Universal Time (word order from French). An
international time standard that has replaced Greenwich Mean
Time.
V
valid signal
A valid signal is a signal that the receiver responds to by
unmuting the receiver. A signal is valid, for example, when it is
stronger than a minimum level and when it has the specified
NAC.
vocoder
Voice encoder/decoder. A processing element that compresses/
decompresses the digital voice signal.
VoIP
Voice over IP. The name for the technology that puts speech
signals in packets and then routes them over an IP backbone
network.
voting
Voting is the systematic sampling of a group of channels for the
channel with the greatest signal strength. Voting provides wide-
area coverage and ensures that as the user moves throughout the
coverage area the strongest channel is always available for a call.
The TB9100 has an internal voter, which decides which base
station input is passed to the switch for distribution to the
configured and enabled outputs.
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.