6816985H01-F February 14, 2012
Glossary Glossary-3
Repeater Remote transmit/receive facility that re-transmits received signals in 
order to improve communications coverage.
RESET Reset line; an input to the microcontroller that restarts execution.
RF PA Radio Frequency Power Amplifier. Amplifier having one or more active 
devices to amplify radio signals.
RSS Radio Service Software.
RPT/TA RePeaTer/Talk-Around.
RX DATA Recovered digital data line.
Serial 
Communication 
Interface Input Line 
(SCI IN)
A full-duplex (receiver/transmitter) asynchronous serial interface.
Signal Qualifier 
Mode
An operating mode in which the radio is muted, but still continues to 
analyze receive data to determine RX signal type.
SCI IN Serial Communication Interface INput line.
Smart RIB Smart Radio Interface Box; a service aid that enables communications 
between the radio and the computer’s serial communications adapter. 
Used in conjunction with the RSS to read the DSP Code, FLASHcode, 
Host Code, and model number.
Softpot Software potentiometer; a computer-adjustable electronic attenuator.
Software Computer programs, procedures, rules, documentation, and data 
pertaining to the operation of a system.
SPI Serial Peripheral Interface; how the microcontroller communicates to 
modules and ICs through the CLOCK and DATA lines.
Squelch Muting of audio circuits when received signal levels fall below a pre-
determined value.
SRAM Static-RAM chip used for volatile, program/data memory.
SSI Synchronous Serial Interface on the DSP, consisting of six signals and 
used for an RX and TX modulated data interface to the KRSIC.
Standby Mode An operating mode whereby the radio is muted but still continues to 
monitor data.
System Central 
Controllers
Main control unit of the trunked dispatch system; handles ISW and 
OSW messages to and from subscriber units (see ISW and OSW).
System Select The act of selecting the desired operating system with the system-select 
switch (also, the name given to this switch).
Term Definition