ALC- Automatic 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
ASF IC- Audio Signalling Filter Integrated Circuit
Closed architecture- A controller configuration that utilizes a microcomputer with internal ROM, RAM, and EEPROM
DTMF- Dual Tone Multi-frequency
DPL- Digital Private-Line™
Firmware- Software 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
FLASHport
™
- Is a Motorola term that describes the ability of a radio to change memory. Every FLASHport radio contains a
FLASHport EEPROM memory chip that can be software written and rewritten to, again and again.
ISW- Inbound Signalling Word; data transmitted on the control channel from a subscriber unit to the central control unit
LSH- Low Speed Handshake; 150 baud digital data sent to the radio during trunked operation while receiving audio
MDC- Motorola Digital Communications
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
Open architecture- A controller configuration that utilizes a microprocessor with extended ROM, RAM, and EEPROM
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 reference, 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
Registers- Short-term data-storage circuits within the microcontroller
Repeater- Remote transmit/receive facility that re-transmits received signals in order to improve communications coverage
RESET- Reset line; an input to the microcontroller that restarts execution
RF PA- Radio Frequency Power Amplifier
RSSI- Received Signal Strength Indicator; a dc voltage proportional to the received RF signal strength
RPT/TA- Repeater/Talk-Around
RX DATA- Recovered digital data line
SCI IN- Serial Communication Interface Input line
SLIC- Support-Logic IC; a custom gate array used to provide I/O and memory expansion for the microprocessor
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
SRAM- Static-RAM chip used for scratch-pad memory
Standby mode- An operating mode whereby the radio is muted but still continues to receive data
System central controller- Main control unit of the trunked dispatch system; handles ISW and OSW messages 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
TSOP- Thin Small-Outline Package
µC- Microcomputer
µP- Microprocessor
VCO- Voltage-Controlled Oscillator; an oscillator whereby the frequency of oscillation can be varied by changing a control
voltage
VCOB IC- Voltage-Controlled Oscillator Buffer Integrated Circuit
VSWR- Voltage Standing Wave Ratio
iv
GLOSSARY OF TERMS
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