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Glossary-2
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.
PA Power amplifier.
paging One-way communication that alerts the receiver to retrieve a message.
PTT See Push-to-Talk.
Publication Manual 
Revision
A publication that provides supplemental information for its parent
publication before it is revised and reissued.
Push-to-Talk The switch or button that causes the radio to transmit when pressed. 
When the PTT switch or button is released, the unit returns to standby 
or receive operation.
radio frequency The portion of the electromagnetic spectrum between audio sound and 
infrared light (approximately 10 kHz to 10 GHz).
RAM See random access memory.
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.
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.
RESET Reset line: an input to the microcontroller that restarts execution.
RF See radio frequency.
RX Receive.
signal An electrically transmitted electromagnetic wave.
software Computer programs, procedures, rules, documentation, and data 
pertaining to the operation of a system.
time-out timer A timer that limits the length of a transmission.
TOT See time-out timer.
transceiver Transmitter-receiver. A device that both transmits and receives analog 
or digital signals. Also abbreviated as XCVR.
transmitter Electronic equipment that generates and amplifies an RF carrier signal, 
modulates the signal, and then radiates it into space.
Term Definition