Raymarine Ray48 manual Glossary of Terms

	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

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