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xvi
List of terms
411-2021-111 Standard 01.01 June 1996
ST
Signaling Tone. In AMPS cellular, a 10 kHz tone transmitted on the Reverse
Voice Channel (RVC) as a precursor to messaging activity, and for certain call-
processing functions (acknowledgments, call termination). Presence of the tone
mutes normal conversational audio.
STSR
Sectored-Transmit/Sectored-Receive. A cell configuration in which a different
control and voice frequency assignment is designated for each sector. A
directional antenna system is required for each sector.
TDMA
Time Division Multiple Access. A modulation and transmission format that
allows a number of digital conversations (three in TDMA-3) to occur within the
same Radio Frequency (RF) channel. Mobile units take turns transmitting/
receiving data on specific time slots of a TDMA frame.
TRU
Transmit Receive Unit. The TRU is a Digital Signal Processing (DSP) based
transceiver capable of two modes of operation, analog (AMPS) and digital
(TDMA).
VCH
Voice Channel. A Radio Frequency (RF) channel used to transmit cellular voice
conversations. The VCH is also an integral part of call setup, handoff, and
disconnect.
VSWR
Voltage Standing Wave Ratio. A measure of the mismatch between the
transmitter source impedance and the load impedance to which it is connected. It
is defined by the following relationship:
Reflected Power
Forward Power
1 +
Reflected Power
Forward Power
1 -
VSWR =