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SCI IN Serial Communication Interface INput line
SLIC Support-Logic IC; a custom gate array used to provide I/O and memory
expansion for the microcontroller.
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 DSP56001 consisting of six signals and
used for an RX and TX modulated data interface to the ADSIC.
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).
TOT Time-Out Timer; a timer that limits the length of a transmission.
TSOP Thin Small-Outline Package
UART Universal Asynchronous Receiver Transmitter.
µC Microcontrol unit (see MCU).
VCO Voltage-Controlled Oscillator; an oscillator whereby the frequency of
oscillation can be varied by changing a control voltage.
VCOB IC Voltage-Controlled Oscillator Buffer IC
Vocoder VOice enCODER; the DSP-based system for digitally processing the analog
signals, includes the capabilities of performing voice compression algorithms
or voice encoding.
VSELP Vector Sum Excited Linear Predictive coding; a voice encoding technique used
in ASTRO digital voice.
VSWR Voltage Standing Wave Ratio