Motorola PM1200, Basic Service Manual

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October 26, 2007 6880309U09-A
Glossary-4
liquid-crystal display An LCD uses two sheets of polarizing material with a liquid-crystal
solution between them. An electric current passed through the liquid
causes the crystals to align so that light cannot pass through them.
LO See Local oscillator.
Local Oscillator Oscillator used in a super heterodyne receiver to down-convert a
received signal to the intermediate frequency.
Master In Slave Out SPI data line from a peripheral to the MCU.
Master Out Slave In SPI data line from the MCU to a peripheral.
MCU See microcontroller unit.
MDC Motorola Digital Communications.
MHz See Megahertz.
Megahertz One million cycles per second. Used especially as a radio-frequency
unit.
microcontroller unit Also written as µC. A microprocessor that contains RAM and ROM
components, as well as communications and programming components
and peripherals.
MISO See Master In Slave Out.
MOSI See Master Out Slave In.
multiplexer An electronic device that combines several signals for transmission on
some shared medium (e.g., a telephone wire).
MUX See multiplexer.
oscillator An electronic device that produces alternating electric current and
commonly employs tuned circuits and amplifying components.
PA Power amplifier.
PC Board Printed Circuit Board. Also referred to as a PCB.
phase-locked loop A circuit in which an oscillator is kept in phase with a reference, usually
after passing through a frequency divider.
PL See private-line tone squelch.
PLL See phase-locked loop.
private-line tone
squelch A continuous sub-audible tone that is transmitted along with the carrier.
See also DPL.
Programmable
Read-Only Memory A memory chip on which data can be written only once. Once data has
been written onto a PROM, it remains there forever.
Term Definition