December, 2009 68009328001-A
G-2
PLL Phase-Locked Loop: a circuit in which an oscillator is kept in phase with a
reference, usually after passing through a frequency divider.
PTT Push-To-Talk: the switch located on the left side of the radio; when pressed,
causes the radio to transmit.
RAM Random Access Memory: the radio’s RAM is loaded with a copy of the
EEPROM data.
Registers Short-term data-storage circuits within the microcontroller.
RESET Reset line: an input to the microcontroller that restarts execution.
RF PA Radio Frequency Power Amplifier
RIB Radio Interface Box
ROM Read Only Memory
RSSI Received Signal-Strength Indicator: a dc voltage proportional to the received RF
signal strength.
RPT/TA Repeater/Talk-Around
Softpot A computer-adjustable electronic attenuator
Software Computer programs, procedures, rules, documentation, and data pertaining to
the operation of a system.
SPI (clock and data
lines)
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.
Standby Mode An operating mode whereby the radio is muted but still continues to receive data
TOT Time-Out Timer: a timer that limits the length of a transmission.
TPL Tone Private-line
µC Microcontroller
UHF Ultra High Frequency
µP Microprocessor
VCO Voltage-Controlled Oscillator: an oscillator whereby the frequency of oscillation
can be varied by changing a control voltage.
VCOBIC Voltage-Controlled Oscillator Buffer Integrated Circuit
VHF Very High Frequency
VSWR Voltage Standing Wave Ratio
Term Definition
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