Here are definitions for some common GMRS and Radio terms:

10 Codes - Or Ten-codes, officially known as ten signals, are brevity codes used to represent common phrases in voice communication, particularly by law enforcement and in Citizens Band (CB) radio transmissions. Avoid. Not universal.

73 - Meaning "Best Regards," a popular abbreviation commonly used in Amateur Radio, and most frequently in Morse code, to signal "Goodbye."

AC - Short for Alternating Current, where the current (or electrical flow) constantly reverses direction. Your house electrical power is an example of AC. 

Band - A group or range of radio frequencies, such as "Citizen's Band," "FM Band," or GMRS Band.

Bandwidth - A measure of the width of a range of frequencies, measured in hertz (cycles per second)

Base Station – A non-handheld radio setup for use at home or office with a 12-volt DC power supply that plugs into a 120-volt AC power outlet.

CB - Short for "Citizens Band." A type of low-power "Personal Radio Service," as designated by the Federal Communications Commission.

Channel - a narrow span of frequencies assigned for the operation of television, radio, or other broadcast stations

Coax, or Coaxial Cable - A type of transmission line, used to carry high-frequency electrical signals with low losses. It has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield. Many coaxial cables also have an insulating outer sheath or jacket.

CTCSS Tone - FRS and GMRS radios frequently have provisions for using sub-audible tone squelch (CTCSS and DCS) codes, filtering out unwanted chatter from other users on the same channel. Also, see PL Tone.

dB - Short for "decibel," is a unit of power measurement often used with antennas and cables to express the amount of power gain or loss. Every 3 dB of antenna gain would increase the power fed into it by 100%. An antenna with 6 dB of gain would increase the power fed into it by 400%. Conversely, a cable with 3 dB of loss would lose 50% of the power fed into it. A cable with 6 dB of loss would lose 75% of the power fed into it.

DC - Short for "Direct Current," where the current (or electrical flow) constantly flows in just one direction. All computers and radios use DC power, although some may be equipped with an AC to DC power converter. 

Directional Antenna - An antenna that sends and receives most of its signal in one direction. A TV antenna on a rooftop is an example of a directional antenna.

Duplex – Refers to a radio that transmits on one frequency and receives on another frequency, with a small offset between them to prevent the two signals from interfering with each other. Duplex is most often used for radio-to-Repeater communications. 

Dual band – A type of radio capable of using both VHF and UHF frequency bands. Many Handie Talkie radios, and especially those favored by the Ham Radio community, are dual-band radios.

FM - Short for "Frequency Modulation," a type of low-noise, high-fidelity radio transmission. For this reason, most music is broadcast over FM radio

FRS - Family Radio Service. A type of low-power "Personal Radio Service," as designated by the Federal Communications Commission. These are the common, retail "blister-pack" walkie Talkie radios sold at Wal-Mart, Best Buy, Home Depot, and others. FRS radios are low-powered, Handie Talkies only, have non-detachable antennas, and cannot transmit to Repeaters. FRS service does not require a license to operate.

Frequency - The number of occurrences of a repeating event per unit of time.

Gain - The amount by which an antenna might increase the signal fed to it. Also, see "dB."

GMRS - General Mobile Radio Service. Operating within the UHF frequency band between 462 to 467 MHz, GMRS is a popular type of "Personal Radio Service," established by the Federal Communications Commission. Mainly because of its higher power limits and thus greater potential to cause interference at a distance, this service requires a license to operate.

Ham – Amateur radio Operator. The term’s origins are debated, but some believe it was originally a derogatory term used by experienced telegraph operators to diss “ham-fisted” or less-experienced operators.

Handie Talkie - Also known as a Walkie Talkie, or portable radio, a Handie Talkie is a type of self-contained, battery-operated, two-way radio that can be easily carried and used.

HF - Short for "High Frequency," A range of radiofrequency waves between 3 and 30 megahertz (MHz). HF bands have the potential for the longest range up to 1,000s of miles and are popular with "Short-wave listeners" and Amateur Radio operators for this reason. 

HT –  A Handheld radio, aka handheld transceiver or Handie-Talkie.

kHz - A frequency abbreviation for "kilohertz," or 1,000 Hertz (1 Hz = 1 cycle per second)

Mag Mount - A type of mount used with mobile antennas that holds the antenna to the top of a car using a magnet.

MHz - A frequency abbreviation for "megahertz," or 1,000,000 Hertz

Mobile – A (usually) non-handheld "mobile" radio for use in a vehicle on 12V DC battery power. These radios are normally connected to a vehicle's 12-volt battery electrical system and a vertical "whip" antenna mounted outside the vehicle. Mobile radios can also be used at home or office with an external 12-volt power supply and an outdoor antenna.

MURS - Multi-use Radio Service. Operating at 151 to 154 MHz, a type of low-power "Personal Radio Service," similar to Citizens Band, established by the Federal Communications Commission in 2000.

NMO - Short for "New Motorola," a type of popular, threaded mobile antenna connector that attaches the antenna to the base.

Net - A kind of regular, weekly radio "round table" where radio users can check-in and talk to each other

Omnidirectional Antenna - A type of antenna which radiates equal radio power in all directions perpendicular to its long axis. A whip antenna on a handie talkie is an example of an omnidirectional antenna.

One-To-Many - A term used to describe transmissions where a radio signal broadcast from one transmitter can be received by many receivers.

One-to-One - A term used to describe transmissions where a radio signal broadcast from one transmitter can be received by only one receiver. A cell phone is an example of a one-to-one device.

One-way Radio - A type of radio that can only receive and cannot transmit. Police and Fire Scanners and Weather Radios are examples of one-way radios.

Pager - A type of One-way Radio used to receive short text and voice messages and alerts. Different models of pagers use frequencies in the VHF or UHF bands, and can receive radio signals set through repeaters. 

PL Tone - A type of sub-audible tone used to prevent multiple signals using the same frequency from interfering with each other. Also, see CTCSS Tone.

Propagation - The varying ability of radio waves to travel in different directions through space or around obstacles, including curvature of the earth, the air, weather, trees, buildings, etc.

PTT Button - The "Push-To-Talk" button on a Handie Talkie or microphone that is pressed in order to transmit.

Q-Codes - A standardized collection of three-letter codes all of which start with the letter "Q". It is an operating signal initially developed for commercial radiotelegraph communication and later adopted by other radio services, especially amateur radio. Avoid. Not universal

Repeater - A type of radio "relay" that receives transmissions sent on one frequency and then rebroadcasts those transmissions on another frequency. Used to extend the range of normal radio communications.

RF – Short for "Radio Frequency."

RX – Short for Receive" or "Receiver." Many radios are "RX only" in that they can receive signals but not transmit them.

Scanner - A type of receive-only radio that can be set to "scan' across a wide range of frequencies until it detects a radio transmission and then stops. Used mainly to monitor police, fire and emergency frequencies.

Simplex - Direct, Radio-to-radio communications without the use of a repeater.

Squelch - A circuit function that acts to suppress the audio output noise of a receiver in the absence of a sufficiently strong desired signal.

Start-Up Tone - The audible tone or beep emitted by your radio when starting up to alert you that the device is functioning.

SWL - Short for Short-Wave Listening. Short Wave is another name for "High Frequency," or HF - a range of radiofrequency waves between 3 and 30 megahertz (MHz). Within these frequencies, Short-wave Listeners can receive radio transmissions from 1,000s of miles away.

Two-way Radio - A type of radio that can send and receive. All Handie Talkies are examples of two-way radios.

TX – Short for "Transmit" or "Transmitter." Many radios are "TX / RX" capable, meaning they can "transmit" and "receive."

UHF - Short for "Ultra High Frequency," A range of radiofrequency waves between 300 megahertz (MHz) and 3 gigahertz (GHz).  For amateur radio communications, this typically means 420 to 450MHz, often referred to as the “440” or “70-centimeter” band. At 462 and 467 MHz, the frequencies used by GMRS are within the UHF frequency band. 

VHF - Short for "Very High Frequency," A range of radiofrequency waves between 30 megahertz and 300 megahertz (MHz).  For amateur radio communications, this typically means 144 to 148MHz, often referred to as “144” (the frequency) or “2-meter” (the wavelength in meters).

Walkie Talkie - See Handie Talkie

Watt - a unit of power measurement - In radio, each doubling of signal watts equals a doubling of power: 10 watts equals two times the power of 5 watts, 20 watts equals four times the power of 5 watts, and forty watts equals 8 times the power of 5 watts.

Weather Radio - A type of One-way Radio used to receive severe-weather announcements and other emergency-warning alerts. Many can be programmed to receive alerts specific to your ZIP Code using Specific Area Message Encoding, or S.A.M.E. Technology.

Yagi or Yagi Antenna - A type of "Directional Antenna," which sends and receives most of its signal in one direction. Named after one of its inventors, Hidetsugu Yagi. Outdoor TV antennas are good examples of Yagi antennas. 

Zone - A grouping of related channels. A programmable radio may have one or more related channels, grouped together in a "Zone." For example, you could have a radio with a zone named "GMRS." You would then first select that zone to access those channels. Into that zone, all of your radio's GMRS channels could be grouped together to make them easier to find.

NOTE: Neighborhood Radio Watch Programs ARE NOT a replacement for Emergency Services such as Police, Fire, the Sheriff's Office or 911. These programs are intended solely as a backup communications solution When All Else Fails.

The El Dorado County Amateur Radio Club is a "not-for-profit," all-volunteer Community Service organization. Members are not reimbursed for their Membership or for services provided to the Community. All of the Community Radio equipment we furnish is provided at or below our out-of-pocket costs, and our general support services are offered free of charge. Radio acquisition, programming, and training workshops provided by our Club Members are free of charge. If people need help installing their equipment at home, unpaid Volunteer assistance may be available. Donations to the Club to sustain our efforts are gratefully accepted but are not required nor expected.

Alan Thompson, Public Information Officer
The El Dorado County Amateur Radio Club
Phone: 530-417-1451