Glossary-2
MRTI Motorola Radio-Telephone Interconnect: a system that provides a repeater
connection to the Public Switched Telephone Network (PSTN). The MRTI
allows the radio to access the telephone network when the proper access code
is received.
MSK Minimum-Shift Keying.
OMPAC Over-Molded Pad-Array Carrier: a Motorola custom package, distinguished by
the presence of solder balls on the bottom pads.
OSW Outbound Signalling Word: data transmitted on the control channel from the
central controller to the subscriber unit.
PassPort™ Enhanced trunking protocol developed by Trident Micro Systems that links
wide area dispatch networking.
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
reference, usually after passing through a frequency divider.
PPM Parts Per Million.
PTT Push-To-Talk: the switch located on the left side of the radio which, 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.
Repeater Remote transmit/receive facility that retransmits received signals to improve
communications coverage.
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 Software Potentiometer: 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.
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