Raymarine Ray48 - Manual (Page 5)

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GLOSSARY OF TERMS
VHF ............................................................. Very High Frequency 30MHz to 300MHz
FM ............................................................... Frequency Modulation
Carrier Wave ................................................ A Radio Frequency on which intelligence is superimposed.
Dual Watch .................................................. Monitor channel 16 while working on another channel.
Tri Watch ..................................................... Monitor channel 16 and weather channel while working on another
channel.
All Scan ....................................................... Scans all channels
Memory Scan .............................................. Scans only user selected memory channels
US Channels ................................................ Channel designations as defined by the FCC
International Channel .................................. Channel designator as defined by International Telecommunication
Union
Weather Channels ........................................ Channels for routine and emergency weather information
broadcast by NOAA
NOAA ......................................................... National Oceanographic and Atmospheric Administration
RTCM .......................................................... Radio Technical Commission for Maritime Services
Simplex ........................................................ Transmit and receive on the same frequency
Duplex ......................................................... Transmit and receive on different frequencies
Squelch ........................................................ A circuit that sets the threshold for cutting off the receiver when
the signal is too weak for reception of anything but noise.
LCD ............................................................. Liquid Crystal Display
TX ................................................................ Transmit
RX ............................................................... Receiver
RF ................................................................ Radio Frequency
CPU ............................................................. Central Processing Unit
PLL .............................................................. Phase Locked Loop (A type of frequency Synthesizer)
VCO ............................................................. Voltage Controlled Oscillator
PTT switch ................................................... Microphone Push-To-Talk switch