Motorola XTL 1500, Подробное руководство по обслуживанию

Страница: 437 / 452

June 15, 2005 6815854H01-A
Glossary-6
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.
PROM See Programmable Read-Only Memory.
PTT See Push-to-Talk.
Push-to-Talk The switch or button usually located on the left side of the radio which,
when pressed, causes the radio to transmit. When the PTT is released,
the unit returns to receive operation.
radio frequency The portion of the electromagnetic spectrum between audio sound and
infrared light (approximately 10 kHz to 10 GHz).
radio frequency
power amplifier Amplifier having one or more active devices to amplify radio signals.
Radio Interface Box A service aid used to enable communications between a radio and the
programming software.
Radio Service
Software DOS-based software containing the feature set of an ASTRO radio. See
also CPS.
random access
memory A type of computer memory that can be accessed randomly; that is, any
byte of memory can be accessed without touching the preceding bytes.
RAM See random access memory.
read-only memory A type of computer memory on which data has been prerecorded. Once
data has been written onto a ROM chip, it cannot be removed and can
only be read.
real-time clock A module that keeps track of elapsed time even when a computer is
turned off.
receiver Electronic device that amplifies RF signals. A receiver separates the
audio signal from the RF carrier, amplifies it, and converts it back to the
original sound waves.
registers Short-term data-storage circuits within the microcontroller unit or
programmable logic IC.
repeater Remote transmit/receive facility that re-transmits received signals in
order to improve communications range and coverage (conventional
operation).
repeater/talkaround A conventional radio feature that permits communication through a
receive/transmit facility, which re-transmits received signals in order to
improve communication range and coverage.
Term Definition