Glossary
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PTT Push-To-Talk; the switch located on the left side of the radio which, when pressed,
causes the radio to transmit.
Registers Short-term data-storage circuits within the microcontrol unit or programmable logic IC.
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
RPT/TA RePeaTer/Talk-Around
RX DATA Recovered digital data line.
Signal Qualifier Mode An operating mode whereby the radio is muted but still continues to analyze receive data
to determine RX signal type.
SCI IN Serial Communication Interface INput line
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.
Standby Mode An operating mode whereby the radio is muted but still continues to monitor data.
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.
Vocoder VOice enCODER; the DSP-based system for digitally processing the analog signals,
includes the capabilities of performing voice compression algorithms or voice encoding.
VSWR Voltage Standing Wave Ratio