Motorola PROFILE 300 Service Manual download pdf (Page 65)

G-ii Glossary

OSW Outbound Signalling Word: data transmitted on the control channel from the

central controller to the subscriber unit.

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 refer-

ence, usually after passing through a frequency divider.

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

Standby Mode An operating mode whereby the radio is muted but still continues to receive

data

System Central Con-

troller

Main control unit of the trunked dispatch system; handles ISW and OSW mes-

sages 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.

TPL Tone Private-Line

µC Microcontroller

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Motorola PROFILE 300 Service Manual Page 65