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Phillip J. Boucher 


GMRS Glossary


Alarm Mode

Enables the radio to power on or beep a signal at a particular pre-programmed time. This is a good feature for pre-arranged check-ins.

Alpha Numeric Display

The use of both letters and numbers on a radio’s display. For example, a radio’s display that shows “CH 1” for Channel One, is referred to as an alphanumeric display.


This small rubber-coated or metal tube rises from the radio. Its purpose is to send and receive radio waves. In Canada, the antenna must be permanently attached to the GMRS radio. Some GMRS radio antennas are collapsible or foldable allowing the unit to fit into a pocket or purse with ease when not in use. The antenna is a highly crucial part of the radio and it is extremely vital that it not be damaged or destroyed in any way. Without an antenna, the radio is useless. Also see Rubber Duck.

Auto-Power Off

Allows the radio to be pre-programmed to turn itself off after a specific period of inactivity to conserve battery power. It is also handy when the user falls asleep with the radio on.

Baby Mode, Baby Monitor, Babysitter Feature

Very similar to wireless baby monitors. The radios are set to “baby” mode and one radio is placed in the room to be monitored. While there, it is constantly listening for noise. When it hears something, it automatically keys up and transmits a signal, which is picked up by a radio in another part of the house or building. Many VOX (Voice Operated Transmit) XE "VOX" -equipped radios can be used in the same manner.

Back Light/Illuminated Display

Turns on the display’s back light for as long as the button is held down, or for a short duration of time after the button is released.

Battery Meter Indicator

A light, symbol on the display, or audible signal that indicates the relative amount of battery power left on the radio. Although mostly calibrated for alkaline batteries or the supplied battery packs, this meter is relatively effective in showing the level of power of NiCad and nickel metal hydride batteries as well. This very handy option enables a user to change out the batteries so the radio does not cut out during transmission.

Battery Saver Circuit

Cuts the power at regular intervals to all radio circuitry except for the receiver. When a signal is heard, it turns on the speaker. Power saver intervals can be applied to the receiver every half second, ten times a second, or could be user selectable. This saves battery power by limiting the radio’s load on the batteries while still allowing incoming calls to be heard.

Batteries/Battery Packs

Provide power to the radio. Most radios use from one to four AAA or AA size batteries, while others use dedicated battery packs. AAA and AA batteries are designed for either one-time use (primary) until they are depleted, or are rechargeable (secondary) for multiple-depletion use. There are four basic types of AAA and AA batteries that can be used with GMRS radios: nickel cadmium (secondary), nickel metal hydride (secondary), lithium ion (primary and secondary), and alkaline (both primary and secondary). In an emergency, cheaper regular and dollar store brand batteries can be used, but they will not last very long. Regular or rechargeable alkaline batteries are good for all around use. Lithium ion batteries last longer but are more expensive. Nickel cadmium batteries (hard to find) or nickel metal hydride batteries (most common and preferable) are the best to use for GMRS radios.

Business Exclusive Radios/Frequencies

Radios similar to GMRS but operate on specific licensed “business” frequencies. These radios are simply the old business band radios repackaged to compete against GMRS radios. Business Exclusive radios come in VHF and UHF versions, with two watt and five watt power outputs, but the two watt UHF radios dominate the industry. There are no advantages to the two watt UHF business radios over GMRS radios. Business exclusive radios are exceedingly more expensive to purchase, and some may only be available for lease or rent. Each radio and each operating frequency requires the user to obtain a license from Industry Canada. The only “advantage” widely touted is that business exclusive frequencies are licensed; therefore there will be fewer users to interfere with communications, unlike GMRS where even children can found on the air. However, in an urban area with a limited amount of business frequencies available, there may be overwhelming interference from other licensed business radio users. Potential users must decide if the purchase and operating costs of business radios justify the “exclusive” factor. In most cases they do not, and GMRS is simply more cost effective.

Call Tone

Distinguishes between different incoming calling stations. Depending how each manufacturer configures this feature, Call Tone settings are set for each radio. When a transmission is received, the radio will beep or ring with a distinct tone that identifies which user or radio is transmitting.


The designated number of a certain frequency or set of frequencies. On CB, channel 10 is 27.075 MHz. Marine channel 10 is 156.500 MHz. In commercial and Amateur Radio, a channel may have different transmit and receive frequencies to access repeater operations. Sometimes “Channel” and “Frequency” are used interchangeably. In GMRS, different brands or models may have different channel/frequency assignments, but most GMRS radios have all twenty-two “channels” available.

Channel Lockout

Enables the user to lockout a channel or frequency during scan or selection modes.


The device that recharges batteries, cells, or packs. Most GMRS radios that come with battery packs also come with desktop or wall charges. Rechargeable AA and AAA batteries are placed into their own type of charger.

Courtesy Beep/Confirmation Beep

Transmits a tone or ring when the radio is unkeyed (the push-to-talk button is released) indicating that the transmitting party has stopped talking and other station may go ahead.


Continuous Tone-Coded Squelch System. When activated on a GMRS radio, CTCSS provides a way of keeping the audio quiet until a signal with the same sub-audible CTCSS tone is received. It then opens the audio for the user to hear. Below is a chart of the CTCSS frequencies in Hz (cycles per second.) 

























































CTCSS is an effective way of hearing only other users in a specific group. However, there are two problems with CTCSS. It is not a privacy feature. Any GMRS radio that is monitoring the frequency with the same code enabled, or without any codes enabled, can hear all transmissions on that frequency whether the transmitting radios are using CTCSS or not. Since only one transmission can be made at a time, two or more signals on the same channel with different CTCSS tones may still interfere with each other.


Stands for Digital Coded Squelch. Where CTCSS uses a sub audible tone along with the transmitted audio, DCS uses a digital code instead. When both transmit and receive radios are set to the same DCS code, the squelch opens the audio circuitry. There are currently 83 DCS codes available. Some radios are able to use both CTCSS and DCS together for better interference blocking. Like CTCSS, DCS is not a privacy feature, and any radio monitoring the frequency with the same DCS code, or without any codes enabled, can hear all transmissions.

Dead Carrier

The unmodulated signal from a transmitter, i.e. transmitting but not saying anything into the microphone so the only thing heard is “dead air.” A dead carrier could also indicate a problem with the transmit audio section of the radio or with the microphone itself.

Display/LCD Display

Shows the operating parameters of the radio such as the channel, CTCSS tone, battery level, transmit power, receive strength, and other similar information. Most GMRS displays are backlit by a light for use in low lighting conditions.

Dual Watch

Lets you monitor two separate channels or frequencies at the same time. This can be quite convenient in search and rescue or event coordination in which users need to operate continuously on a designated channel/frequency but also need to hear emergency or priority communications on another channel/frequency.

Duty Cycle

Length of time that a battery will last under normal use, which is generally considered to be approximately 5% transmitting, 5% receiving, and 90% in standby or monitoring mode. Under normal use in a typical GMRS radio, alkaline batteries will last about 30 hours and NiMH (nickel metal hydride) rechargeable batteries will provide about 11 hours of operation. With more transmitting time used, alkaline battery capacity will diminish faster than NiMH, thereby giving the NiMH batteries a better duty cycle. Duty cycle is a subjective standard measurement and can vary greatly due to differences in brands and models of radios and batteries.

ERP, Effective Radiated Power

The effective, or actual, power of the transmitted signal measured as it comes out of the antenna. GMRS radios are limited to two watts maximum ERP, even if the power from the final amplifier is more than the maximum.

FM (Frequency Modulation)

A method of modulating a radio wave in which the frequency of the signal changes in proportion to the characteristics of the sound waves (such as a voice). The frequency of the radio wave varies while the amplitude remains constant. This is the method used for GMRS communications.


A type of contest that is very popular with Amateur Radio clubs. One or more transmitters are hidden in a remote area and participants use a receiver to “hunt,” “home in” or “zero in on” the signal, either by themselves or while working in groups. The same type of contest can be done with GMRS radios. One person hides in a very secretive area and transmits a signal, such as a short message, like, “This is the Fox. Where am I?”, or they may simply send a call tone, doing so every five to fifteen minutes. Users listen to the signal on their radios and try to find the “fox.” The first person or group that locates the fox gets a prize. Many people use a simple method of covering the entire antenna of the radio with their hand, or may hold the radio close to their body when the signal comes through. This essentially blocks the signal so it is too weak to activate the receiver when the transmitter is too far away. The closer a user is to the Fox (the transmitter) the stronger the signal will be and the more likely the signal will come through. By holding the radio antenna close to the chest and turning around in a circle, the signal will fade in and out. When the signal is strongest, the user is facing the transmitter. When it drops out, is the transmitter is behind the user. Clubs or groups can make up their own rules about the message and transmit intervals, and can even create new ways to play the game or find the Fox.


Family Radio Service. This service, authorized in Canada on April 1, 2000, was in response to demand from the Canadian public and the successful implementation of the same service down in the States. FRS, officially known as the service of Family Radio Devices, uses fourteen frequencies in the 462/467 MHz range with a maximum power output of one half of a watt. It is hard to find FRS only radios today since most radios now combine the FRS frequencies with the GMRS frequencies into one unit.


The number of cycles per second of a transmitted or received signal. For example, the FM radio station 107.1 broadcasts on a frequency of 107.1000 MHz, or 107.1 million cycles per second. Frequencies for GMRS are in the 462 MHz and 467 MHz ranges. Also called Radio Frequency (RF) or Operational Frequency, it is the actual frequency on which radio communications occur.


General Mobile Radio Service. Authorized on September 7, 2004, this service allows the use of radios with greater transmit power up to two watts and more frequency assignments. This puts GMRS radios on an equal footing with the so-called and more expensive Business Exclusive Radios.


Global Positioning System. A GPS receiver, or a GPS equipped GMRS radio, accesses the signals of several orbiting satellites, and using the information from those signals, calculates the exact position on Earth that the receiver is located. GPS is used by governments, shipping, aircraft, hikers, drivers, and many other users who need to know where they are located, or directions to get to a certain location.

Group Calling

A calling method that sends a signal or tone that activates a tone or signal on all receiving radios that are set to that particular calling code.

Handheld, Handie Talkie, HT

A portable transceiver that contains both an antenna and batteries allowing the unit to be taken anywhere by the user. Almost all GMRS radios are handheld units.


Using the radio without manually pressing the push-to-talk button so a user's hands are free to do other tasks. See VOX .


A radio accessory that enables the user to wear either speakers, or a combination of speakers and a microphone, on their head for either hands free communications, or to conduct communications in a noisy environment.


The number of times a second a radio signal oscillates. Megahertz, or MHz, means a million cycles per second. GMRS operates at 462 MHz and 467 MHz (462 and 467 million cycles per second.)

Key, Key Up

Slang term for pressing the PTT (push-to-talk) button to activate the radio’s transmitter. When a user transmits, they “key” or “key up” the radio. This term may come from the fact that in sending Morse Code, a radio user must press a metal lever mounted on a spring to make contact with another piece of metal. This lever and spring are called a “key.” When a user releases the PTT button, they are “unkeying” the radio.


Two or more buttons arranged on the radio that let a user access various options such as channel or mode selection.

Keypad Tones

Tones that sound whenever a user presses a button to give an audible indication that the button has been pressed properly.

Keypad Lock or KeyLock

This feature enables the keypad or buttons to be disabled to prevent them from being accidentally pressed during rough or intense activities. This prevents the unwanted changing of channels or the keying up of the radio.

Line of Site Propagation

The characteristic of VHF and UHF radio signals in that they travel in a straight line and will continue to do so as long they can still “see” the receiving radio. Any obstacles in the way will absorb or deflect the signal, degrading its quality and strength, and possibly making it too weak or just non-existent for the receiving radio to capture. Unobscured radio signals over open water travel further, and are of a much better quality than radio signals in a more urban environment or within a building.

Memory Backup

A circuit in the radio that holds information regarding programmed channels, tones, codes, etc. Memory Backup circuits can be “volatile” in which a battery is needed to power the circuit (and subsequently the information is lost when the battery dies), or “non-volatile,” in which the information is kept even when there is no power to the circuit.

Memory Channel

This feature is used to program a small amount of working channels/frequencies for manual selection or automatic scanning. None of the other channels are available. . For example, a family or company may program channels one, two, and three of a twenty-two channel radio for their use. Channels four to twenty-two are unprogrammed and unused. They won’t show up when channels are scanned or stepped through. This allows users to select the channels/frequencies they require to operate on and aids in quick selection between those channels while ignoring the rest of the channels on the radio.

Mic, Mike, Microphone

A device that converts sound waves such a voice into a form that is transmitted over the radio wave. Microphones come in a variety of styles and designs including those built into the radio, external mics that can clip to a collar, and ones incorporated into headsets.

Monitor/ Monitor Button

Used to check activity on a current channel before transmitting. When pressed, the squelch circuit will be disabled and any low power or distant stations will then be heard.


A pager is a radio receiver that emits a tone and/or vibrates when it receives a special signal from a transmitter. The paging feature on some GMRS radios allow the calling party to page or alert the called party that they would like to talk to them.

Power Output

The amount of transmit power the radio has. For some shared FRS frequencies, the power output is limited to one half of a watt (0.5 watts). For the other shared FRS frequencies, and all the GMRS frequencies, power output is limited to two watts (2 watts). Most radios allow the user to switch output power on the applicable channels. Switchable power enables a user to select between high power for maximum range and low power for battery conservation

Priority Channel/Priority Scan

A channel that is designated as the primary operating channel above all others. Some radios scan the priority channel at regular intervals during normal use or in scan mode, and lock onto the channel when a signal is heard. Some radios also have a button that, when pressed, calls up the priority channel regardless of what else the radio is doing or receiving.

Private or Privacy Codes

See CTCSS and DCS 


A feature that allows the user to program in a certain number of channels, frequencies, or other radio parameters for scanning or operating.


Short for Push-To-Talk. Refers to the button, usually on the side of the radio, that is pressed to turn on the transmitting section of the radio. Releasing the button stops the radio from transmitting and sets it back to receiving.


A combined transmitting and receiving circuit in a small device that sends and receives radio signals. A radio can be a large unit used in a base setting such as at a desk, a small unit used in a car, or an even smaller device that you hold in your hand.


The distance a radio signal travels from the transmitter. As with all VHF/UHF handheld radios, GMRS signal range depends on a number of factors such as output power, antenna quality, terrain, and battery health. Range for two watts of output power is approximately eight to ten kilometres and for half a watt output approximately three kilometres.

Range Extension

Pressing this button temporarily turns off the squelch circuit so you can hear any weak stations that can’t break the squelch. This is the same as Monitor or the Monitor Button. This feature really does not extend the receiving range of your radio. It only allows you to hear weaker stations that are not strong enough to break through the squelch.


To hear, get, or otherwise intercept a radio signal and transform it back into audio.


Independent or integrated circuitry that is designed to pick up radio signals from the air on a specific frequency or set of frequencies. GMRS radios all combine the receiver and transmitter into one compact unit.


A device that takes an incoming radio signal and retransmits it at a higher power over a greater distance to extend radio communications range. GMRS repeaters are illegal in Canada.

Roger Beep

See Courtesy Beep

Rubber Duckie/Rubber Duck

The common name applied to the antenna that usually is on any portable or handheld radio. It generally consists of a straight or coiled steel or copper wire encased in a rubber or plastic type coating, making it flexible and useable in a variety of situations in which a solid metal antenna may be damaged.


Short form for Receive or Receiver.


Automatically searches through a number of channels, memory channels, frequencies, or tones, and then stops when it hears activity to monitor the transmission. When the signal or activity is over, the feature resumes scanning again. For example, a user may have set their radio to search through channels one through seven. The radio will scan through those channels and when a signal is heard, it will stop on that channel. When the signal is over, it will resume scanning through the channels again, waiting for the next signal, which could be on any other channel of the seven.


A radio emission that travels through the air in all directions to be received by other radios. When you key up (press the PTT or Push-to-Talk button) the radio, you are sending out your signal.

Silent Alert, Silent Calling

See Vibration Alert


The system that GMRS radios use to communicate. Simplex means that all the radios on a frequency transmit and receive on that frequency only without the signal being received and retransmitted by another device, such as a repeater.


Like the speaker on a radio to TV, allows you to hear the audio of stations on the channel you are one, and tones and beeps the radio produces.


A speaker and microphone together in one unit connected to the radio by a cord. This allows the radio to be worn on a belt or in a pocket and the speakermic to be placed on a user's lapel or other area near their ear so they can hear the calls and conveniently access the microphone.


This is a system that keeps the audio on a radio quiet until a signal is received. On many GMRS radios the squelch is permanently set at a pre-determined level and can’t be changed (called Auto-squelch).

Squelch Tail

The noise sometimes heard on radios or repeaters when the transmitter is unkeyed. The signal falls off and it takes a short moment for the squelch system to initiate.


An industry marketing term for a feature that really does not exist. “Sub-channels” are made up of one of the twenty-two GMRS frequencies combined with one of the CTCSS or DCS sub-audible tones to create the impression of thousands of “sub-channels” available to the user. Regardless of the combination of channels and codes/tones used, there are only twenty-two channels/frequencies available for the service.


See Transmit and Transmitter

Time-Out Circuit

Helps to extend battery life and/or prevent a radio transmission that is too long by either emitting a warning signal and/or disabling the transmitter circuitry after a preset time such as fifteen seconds, two minutes, etc.


A radio communications unit that contains both a transmitter and a receiver. Most base, mobile, and handheld radios are typical transceivers. GMRS radios all combine the receiver and transmitter into one compact unit.


The act of keying up a radio (pressing the PTT button) and sending a radio wave through the air to be intercepted by a receiver or receivers.


The part of a radio that sends voice, data, and tone information over the airwaves. When a user presses the PTT button, the radio sends out a signal and places their voice on that signal which is received by other radios. GMRS radios all combine the receiver and transmitter into one compact unit.


Though transponder systems can differ in various makes and models of two-way radios, the principle of operation is the same. The radios send a signal to and receive a signal from each other at regular intervals. Depending on the operational parameters of the system, they may alert the user when the radios become separated by too far a distance, or come into operational range of each other.


Ultra High Frequencies usually referred to from 300 MHz to 1000 MHz. Trunking Radio, Link Systems, Commercial and Public Service, and Amateur Radio XE "Amateur Radio"  are just some the services that operate on UHF frequencies. UHF signals travel a shorter distance than VHF signals but are less susceptible to interference from environmental obstructions.


To release the PTT (Push-to-Talk) button, ending the transmission.

Vibration Alert

This feature vibrates the radio when a signal is received as a physical alert to the user. When the audible alert is turned off, Vibration Alert is sometimes called a Silent Alert or Silent Calling. Most radios allow this feature to be used alone or in conjunction with the audible alert.

Volume Control

A knob or button that controls the level of volume coming out of the speaker. It sometimes doubles as the ON/OFF knob or button.


Voice Operated Transmit. This circuit turns on and off the transmitter whenever it hears a noise, usually a user's voice. This leaves the hands free for other important tasks. Many GMRS radios can use VOX with and without a headset.

Water Resistant

Some radios are designed to be resistant to water entering the unit. This allows them to be used in wetter environments, such as on a boat or in the rain.

Weather Radio, Weather Service, Weather Mode, Weather Channels

Many GMRS radios have the option of being able to receive continuous weather broadcasts from Environment Canada on assigned VHF frequencies across the country, using a separate VHF receiving circuit. Those frequencies are 162.400, 162.425, 162.450, 162.475, 162.500, 162.525, and 162.550 MHz. The signals from each broadcast location cover about sixty kilometres.

Entire contents © 1998 - 2018  Phillip J. Boucher

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