Motorola Two Way Portable Radio Ht750 Ht1250 Mtx850 Mtx1250 Mtx8250 Mtx9250 Basic 68p80906z54 D Manual

							Glossary-1
Glossary
Te r mDefinition
ALCAutomatic Level Control: a circuit in the transmit RF path that controls RF 
power amplifier output, provides leveling over frequency and voltage, and 
protects against high VSWR (voltage standing wave ration).
ASF ICAudio Signaling Filter Integrated Circuit with voice compander.
CDCompact Disk.
CMPCompression.
CPSCustomer Programming Software.
CSQCarrier Squelch.
DTMFDual-Tone Multifrequency.
DPLDigital Private-Line.
EEPROMElectronically 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 
cannot be altered or reprogrammed.
FGUFrequency Generation Unit.
GaAsGallium Arsenide: a type of crystalline material used in some semiconductors.
ISWInbound Signalling Word: data transmitted on the control channel from a 
subscriber 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.
LDMOSLateral 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) 
peripheral.
LLELow 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.
LT RTrunked signaling protocol using low speed data. Registered trademark of E.F. 
Johnson Company.
MDCMotorola Digital Communication. 
						

							Glossary-2
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.
MSKMinimum-Shift Keying.
OMPACOver-Molded Pad-Array Carrier: a Motorola custom package, distinguished by 
the presence of solder balls on the bottom pads.
OSWOutbound 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 BoardPrinted Circuit Board.
PLPrivate-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 
reference, usually after passing through a frequency divider.
PPMParts Per Million.
PTTPush-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.
RegistersShort-term data-storage circuits within the microcontroller.
RepeaterRemote transmit/receive facility that retransmits received signals to improve 
communications coverage.
RESETReset line: an input to the microcontroller that restarts execution.
RF PARadio Frequency Power Amplifier.
RIBRadio Interface Box.
ROMRead Only Memory.
RSSIReceived Signal-Strength Indicator: a dc voltage proportional to the received 
RF signal strength.
RPT/TARepeater/Talk-Around.
SoftpotSoftware 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. 
						

							Glossary-3
Standby ModeAn operating mode whereby the radio is muted but still continues to receive 
data.
System Central 
ControllerMain control unit of the trunked dispatch system; handles ISW and OSW 
messages to and from subscriber units (see ISW and OSW). 
System SelectThe 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.
TPLTone Private-line.
µCMicrocontroller.
UHFUltra High Frequency.
µPMicroprocessor.
VCOVoltage-Controlled Oscillator: an oscillator whereby the frequency of oscillation 
can be varied by changing a control voltage.
VCOBICVoltage-Controlled Oscillator Buffer Integrated Circuit.
VHFVery High Frequency.
VSWRVoltage Standing Wave Ratio. 
						

							Glossary-4
Notes 
						

							6880906Z 54-D
* 6880906Z54*
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