Motorola Cm Radio Basic Manual

							GlossaryI
GLOSSARY
Glossary of Terms
Te r mDefinition
ALC Automatic Level Control: a circuit in the transmit RF path that controls RF 
power amplifier output, provides leveling over frequency and voltage, and pro-
tects against high VSWR (voltage standing wave ration).
ASF ICAudio Signalling Filter Integrated Circuit with voice compander.
CD Compact Disk.
CMPCompression.
CPS Customer Programming Software.
CSQCarrier Squelch.
DTMF Dual-Tone Multifrequency.
DPLDigital Private-Line™.
EEPROM Electronically Erasable/Programmable Read-Only Memory: used by the radio 
to store its personality.
FirmwareSoftware, or a software/hardware combination of computer programs and data, 
with a fixed logic configuration stored in a read-only memory. Information can-
not be altered or reprogrammed.
FGU Frequency Generation Unit.
GaAsGallium Arsenide: a type of crystalline material used in some semiconductors.
ISW Inbound Signalling Word: data transmitted on the control channel from a sub-
scriber unit to the central control unit.
LCDLiquid Crystal Display: a module used to display the radio’s current operating 
channel or system and scan status.
LDMOS Lateral Diffusion MOS.
LH DATALonghorn Data: a bidirectional 0-5V, RS-232 line that uses the microcontroller’s 
integrated RS-232 asynchronous serial communications interface (SCI) periph-
eral.
LLE Low Level Expander: slight amount of volume expansion; used to improve the 
signal to noise ratio.
LSHLow-Speed Handshake: 150 baud digital data sent to the radio during trunked 
operation while receiving audio.
MDC Motorola Data Communication.
MRTIMotorola 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. 
						

							IIGlossary
OSW Outbound Signalling Word: data transmitted on the control channel from the 
central controller to the subscriber unit.
PC BoardPrinted Circuit Board
PL Private-Line® tone squelch: a continuous sub-audible tone that is transmitted 
along with the carrier.
PLLPhase-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.
RAMRandom Access Memory: the radio’s RAM is loaded with a copy of the 
EEPROM data.
Registers Short-term data-storage circuits within the microcontroller.
RepeaterRemote transmit/receive facility that retransmits received signals to improve 
communications coverage.
RESET Reset line: an input to the microcontroller that restarts execution.
RF PARadio Frequency Power Amplifier
RIB Radio Interface Box
ROMRead Only Memory
RSSI Received Signal-Strength Indicator: a dc voltage proportional to the received 
RF signal strength.
RPT/TARepeater/Talk-Around
Softpot Software Potentiometer: a computer-adjustable electronic attenuator
SoftwareComputer 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.
SquelchMuting 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-
trollerMain 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).
TOTTime-Out Timer: a timer that limits the length of a transmission.
TPL Tone Private-Line
µCMicrocontroller 
						

							GlossaryIII
UHF Ultra High Frequency
µPMicroprocessor
VCO Voltage-Controlled Oscillator: an oscillator whereby the frequency of oscillation 
can be varied by changing a control voltage.
VCOBICVoltage-Controlled Oscillator Buffer Integrated Circuit
VHF Very High Frequency
VSWRVoltage Standing Wave Ratio 
						

							IVGlossary