2 Glossary
OMPAC Over-Molded Pad-Array Carrier: a Motorola custom package, distinguished by
the presence of solder balls on the bottom pads.
PC Board Printed Circuit Board
PL Private-Line® tone squelch: a continuous sub-audible tone that is transmitted
along with the carrier.
PLL Phase-Locked Loop: a circuit in which an oscillator is kept in phase with a ref-
erence, 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 EE-
PROM 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-deter-
mined 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
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