Not exactly sure what a feature means? This page provides a plain-English explanation of common two way radio features and terminology.
900 Mhz Frequencies
Radios operating within the 900 Mhz frequency range communicate well both indoors and and outdoors. This is the same frequency range used by many cordless phones. The biggest positive about two way radios using 900 Mhz frequencies is that they can be used by both individuals and businesses without a license from the FCC.
Adjustable Gain
Two way radios with the adjustable gain feature allow you to adjust the sensitivity of your microphone. This is useful along with hands-free operation because it helps minimize the possibility of unintended noises triggering a transmission, or enhances the ability to pick up quiet voices.
Adjustable RF Gain
This feature allows you to fine-tune the receiver sensitivity to pick up a signal with enough strength, but not too much background noise.
Adjustable Squelch
Changes the sensitivity of your radio to adjust for whatever signal strength you may be receiving. Lower squelch levels will allow you to receive transmissions from a greater distance, but these transmissions will contain more background noise. Higher squelch levels reduce the background noise, but will eliminate some weaker transmissions.
Alarm
Radios equipped with an alarm will allow the operator to transmit and/or receive an alarm tone for a specific event.
Altimeter
An altimeter measures altitude of an object, usually to determine how high it is above sea level.
AM Output Power
AM Output Power is the measurement of the range your transmit power will have on AM frequencies.
Antenna Warning Indicator
Radios with this feature display an alert when the antenna needs to be checked..
Audible Button Beeps
Radios with this feature play a tone whenever a button is pressed. This helps you to confirm that the button was actually pressed.
Audio Accessory Connector
Radios with the audio accessory connector feature have a port that will allow you to connect external audio devices to your two way radio. The actual devices supported vary by model. Some of the most popular external accessories are earpieces, speaker microphones, and hands-free kits.
Auto Channel Change
The auto channel change feature will change all radios within your group to a new channel. This helps avoid interference. In order to use the auto channel change feature, all members of your group must have radios supporting this feature.
Auto Power Off
The radio will automatically power off after a set period of inactivity.
Backlit Display
Most two way radios have a digital LCD screen that displays useful information, such as your current channel and customized features. Radios with a display are often lit from behind and may allow you to turn the backlight on, off or even adjust the brightness level to make information easier to read in darker environments.
Battery Charger
A battery charger will re-charge two way radios that operate with rechargeable batteries. If you plan to use your two way radio frequently, rechargeable batteries are a good idea and will pay for themselves in the long run!
Battery Meter
A battery meter will indicate the amount of charge remaining on the battery.
Battery Saver
Two way radios with this feature generally have a "low power" mode that they will switch to automatically after being left unused for a certain amount of time. While in the "low power" mode, the drain on the battery is less than during normal operations.
Battery Type
Two way radios are mobile devices and were intended to move around with you. Because of this, all radios operate on battery power. These batteries fall into one of two categories, either rechargeable or non-rechargeable. The most common type of rechargeable battery in use today is the Lithium-Ion (Li-Ion). Other types of rechargeable batteries include Nickel Cadmium (NiCd) and Nickel Metal Hydride (NiMH).
NiMH rechargable batteries are usually considered superior to NiCd. NiMH batteries usually last longer and have no "memory effect". NiCd batteries do suffer from the "memory effect" and because of this it is recommended that you completely drain your NiCd batteries before you recharge them.
Many consumer radios use standard non-rechargeable alkaline AA or AAA batteries. Some business and amateur radios may also use alkaline batteries if equipped with an optional alkaline battery case.
Bluetooth Capable
A radio that is Bluetooth Capable supports a wireless Bluetooth® device, such as an audio headset.
BRS Channels
BRS is an acronym for "Business Radio Service". Two way radios that are Part 90 type accepted for the BRS operate on VHF or UHF frequencies allocated to businesses and organizations that are licensed by the FCC to use them. BRS channels are the channels that are programmed to those business frequencies.
Busy Channel Lockout
Busy Channel Lockout prevents you from breaking in on a channel already in use. When BCL is activated, the radio will not transmit and an alert tone may sound when the PTT switch is pressed.
Call Tones
Call tones allow you to transmit a tone to other radios in your group to alert them that you want to talk. This is similar to a telephone's ringing to indicate that someone wants to talk to you.
Many radios allow you to choose from several different call tones.
Call Waiting
Call waiting works similar to what you are used to with regular telephones. You will receive a notification that someone is trying to reach you if you are already on a call. Some radios with this feature will provide the option of allowing you to immediately accept the new incoming call, or reject it and call back later.
Caller ID
This feature allows the radio to transmit and/or receive a radio ID, often using dual-tone multi-frequency (DTMF) encoding. Caller ID lets you know who is transmitting to you.
Camera
The unit features a built-in camera.
CB Radio Channels
CB channels are channels that are assigned by the FCC for use by the Citizens Band Service (CB). There are 40 CB channels available. The FCC has limited the amount of power that a device can use to transmit on a CB channel to 4 watts. Radios that are type accepted for CB are licensed by rule or license-free, which means an FCC license is not required to transmit on the CB channels.
Channel Announcement
Channel Announcement audibly voices the channel number/description. This allows the user to change channels without looking at the channel knob.
Channel Mode
In Channel Mode, frequencies that have been saved to the radio can be selected from the channel list.This is the default mode on most programmable radios and the only mode for non-programmable models.
Channel Scan
The channel scan feature enables a two way radio to continuously scan each channel for activity. When activity is detected on a channel, the scan process will stop and you will hear the transmission.
Channels
A channel is defined as a common pathway for radio communications using a specific frequency or set of frequencies assigned to it. As applied to modern two way radios, a channel is a memory location that contains a frequency, filters such as PL (CTCSS) tones, DPL (DCS) codes and possibly other customized settings that are either hard coded into it from the manufacturer or programmed into it by the user. A typical two way radio may have as few as one channel or as many as a thousand or more from which to choose.
To communicate with others using a two way radio, all radios in the group must be set to the same channel containing the same frequency and PL/DPL filter, as applicable.
Clock
Two way radios with a clock will display the current time. Some radios with this feature also have an alarm feature.
Cloning Capable
Two way radios that are cloning capable can have their configuration easily loaded from a different radio. This makes setup a breeze when your business or organization has quite a few radios. Cloning helps when you have purchased lots of radios, when you are adding new radios, or when you make changes to your configuration and need to replicate them quickly across your entire radio fleet.
Many radios that support this feature require that you also have a separate accessory to connect the radios together. This cloning support is often built-in to multi unit charging stations.
Companding
Companding is a sophisticated digital voice compression technology that reduces the static hiss between words. This technology extends the effective range of the radio and delivers noticeably clearer transmission quality.
Contacts List
Provides you with a "phone book" of contacts. You can use this contact list to easily select a channel for a group or individual (for radios supporting direct call).
CTCSS Find
Also known as Tone Scan. Radios equipped with this feature can scan for the CTCSS tone used by other radios on a channel or frequency.
Delta-Tune
Delta-Tune allows you to fine tune incoming signals for greater clarity to reduce interference between adjacent channels.
Digital/Analog Mixed Mode
The radio can operate in both analog and digital modes.
Digital Compass
A digital compass will tell you which direction you are headed. Two way radios with this feature will usually show you abbreviations for your direction while the compass is active. Common abbreviations are: N, E, S, W, NE, NW, SE, SW.
Digital Vocoder
A vocoder is a voice encoder and decoder. It converts analog speech into a digital signal and converts it back to analog.
Dimmer Control
This feature allows you to change the brightness of any illuminated features on the radio.
Direct Call
The direct call feature allows you to make a private call to a single radio within a group. Other radios within the group will not hear the conversation. In order to use the direct call feature, all members of your group must have radios supporting this feature.
Some radios supporting this feature, such as the higher end Midland radios, only support sending a call tone directly to a different radio within the group, and not a voice call.
DMR
Acronym for Digital Mobile Radio. It is an open digital standard used by many digital radio manufacturers.
Drop-In Charge Capable
Two way radios that are drop-in charge capable are compatible with desktop type cradle chargers. In these chargers, you drop the entire radio in a cradle while it recharges.
DTMF Encode and Decode
Dual Tone Multi-Frequency or DTMF is a technology that uses a combination of tones to perform a number of useful signaling operations. Two way radios that support DTMF can send and/or receive radio IDs, call IDs, alerts and other signaling functions.
Dual Band
Radios with Dual Band capability can transmit and receive on both UHF and VHF radio bands.
Dual Channel Watch
Dual channel watch allows you to monitor two channel/privacy code combinations at once.
Eavesdrop Reducer
The eavesdrop reducer feature will allow you to set a special "eavesdrop reducer" code. Setting this code will cause your radio to garble the tranmission for anyone else who may be listening. Another radio with this feature must be set to the same "eavesdrop reducer" code before they will be able to hear your transmission correctly.
This feature does not guarantee secrecy, but it does add an extra layer of privacy.
Emergency Alert
Radios supporting Emergency Alert have a button that, when pressed, will send out a distress call. Other radios within range will alert with the distress call. After sending the distress signal, the transmitting radio will also typically transmit in hands-free mode for a number of seconds.
Escalert
If the radio receives call or text and the user does not respond, the radio emits an alert that becomes louder until the user responds.
Fixed Antenna
Fixed antennas are not able to be removed from the radio.
Flashlight
Radios with a built-in flashlight are a good choice for emergency preparedness kits, for those that would be using a radio during an emergency situation where there may be a power outage, or for those that will simply be using the radio at night.
Floats
The radio can float in water.
Frequency Display
The radio displays the current channel frequency.
Frequency Find
Scans for the frequencies being used by other radios.
Frequency Hopping Technology
Frequency-hopping technology provides enhanced privacy. Radios supporting this feature do not communicate on a single frequency, like standard UHF/VHF radios. Frequency hopping radios will constantly switch frequencies, staying in sync with other radios in your group. This makes it almost impossible for your conversations to be overheard by individuals using other types of radios or scanners.
Frequency Mode
Frequency Mode, also known as VFO Mode, allows you to tune directly to a specific frequency regardless of the frequency having been previously saved into a channel. In Frequency Mode, turning the Channel/Frequency knob or using the keys that change the channel will tune to a higher or lower frequency, depending on which key is pressed. A radio that is equipped with a keypad may even allow you to enter a frequency directly when in Frequency Mode.
Front Speaker
The radio has a built-in front or front mount speaker.
FRS Channels
FRS channels are channels that are assigned by the FCC for use by the Family Radio Service (FRS). These channels are also shared with the General Mobile Radio Service (GMRS). There are 22 FRS channels available. The FCC has limited the amount of power that a device can use to transmit on an FRS channel to 2 watts on channels 1-7 and 15-22, and one half of one watt (0.5 watts) on channels 8-14. Radios that are type accepted for FRS are licensed by rule or license-free, which means an FCC license is not required to transmit on their FRS channels.
GMRS Channels
GMRS channels are channels assigned by the FCC for use by the General Mobile Radio Service (GMRS). These channels are also shared with the Family Radio Service (FRS). There are 30 GMRS channels available. These consist of 22 GMRS simplex channels and 8 GMRS repeater channels. The range limit put in place by the FCC for GMRS is considerably higher than FRS, with a maximum of 5 watts on channels 1-7 and 50 watts on channels 15-22. However, as with FRS, the amount of power that a device can use to transmit on channels 8-14 is limited to one half of one watt (0.5 watts).
The FCC requires that all operators using the GMRS frequencies obtain a radio license before operating their equipment. To obtain this license, request form 605 from the FCC, which includes all forms and instructions.
GPS
Radios equipped with GPS capability can transmit and/or receive GPS position data to or from other radios and/or dispatch stations.
Instant Channel Access
The radio has a button or switch for the sole purpose of selecting a pre-programmed channel. On CB radios this would typically be programmed to channels 9 and 19. Marine radios also have an emergency channel. Some GMRS radios have a programmable key that can be set to a specific channel or frequency.
Interchangeable Face Plates
Two way radios supporting interchageable face plates have snap-off front covers. These "face plates" can be replaced with others to give your radio a fresh look and style!
Intrinsically Safe
Intrinsically safe (IS) is a protection technique for safe operation of electronic equipment in explosive atmospheres. The concept was developed for safe operation of process control instrumentation in hazardous areas. Intrinsically safe devices limit energy which prevent fires & explosions from occurring in areas with hazardous chemicals, gases or other ignitable atmospheres.
Key Tones
Radios with this feature play a tone whenever a button is pressed or the controls are in operation.
Keypad Lock
Radios with the keypad lock feature allow you to "Lock" the buttons so that pressing them has no effect. This is useful if you are carrying the radio on your hip, in your pocket or in a purse where buttons could accidentally get pressed.
Last Channel Memory
Radios with this feature automatically tune to the last selected channel when the radio is first turned on.
Lead Free
Products that are lead free have been certified to contain no lead. Lead free products are generally considered safer to handle and more environmentally friendly.
LED Status Light
The radio has an LED indicator that lights and/or changes color to indicate the receive, transmit, standby or other status of the radio.
Lighted Keys
The keys on the radio light up for use at night or in low light conditions.
Lone Worker Mode
Radios equipped with Lone Worker Mode will emit an audible alarm for a number of seconds at preset intervals when the Lone Worker Time has expired. If the user does not reset the timer by pressing a specified button or switch, the radio switches to Emergency Mode.
Low Battery Alert
Two way radios with the low battery alert feature will alert you in some way when the battery charge is getting low. Some models will provide an audible tone to indicate the battery is low. Other models show a special icon in the display when the battery charge is getting low.
Manager Lockout
Radios supporting the manager lockout feature can have certain features locked, preventing access by the normal user of the radio. This can be used to keep everyone on the same channel and privacy code.
Manufacturer Warranty
This is the warranty provided by the manufacturer for your radio. The length and terms of a warranty vary by manufacturer, and may even vary by the model. Refer to the owners manual of your make and model for specific details.
MDC 1200 Compatible
MDC (Motorola Data Communications) signaling offers selective calling and ANI features.
Memory Card
Device accepts a memory card.
Memory Channels
Two way radios with memory locations allow you to store your frequently used channel/privacy code combinations for easy access later.
Military Specifications
The radio meets one or more military specifications, which should be listed among its features. These specifications may include, but may not be limited to, standards for temperature, vibration, acceleration, shock, and water resistancy. The different military specifications have different standards associated with them, and they should be listed for the radio.
Missed Call Alert
If you have missed a transmission, radios supporting this feature will alert you to let you know you've missed a call.
Mobile Radio
A Mobile radio is a transmitter-receiver (transceiver) used for radio communications from a vehicle. Mobile radios are usually mounted inside a motor vehicle, with a hand microphone and control panel in reach of the driver. In the US, such a device is typically powered by the host vehicle's 12 volt electrical system. Mobile radios are popular with freight haulers, off-roaders and some personal commuters. Mobile radios can be found in police, fire and highway patrol vehicles and on construction sites.
Monitor Channel
This feature allows you to check if a channel is clear before you transmit.
MURS Channels
MURS channels are channels that are assigned by the FCC for use by the Multi Use Radio Service (MURS). There are 5 MURS channels available. The FCC has limited the amount of power that a device can use to transmit on a MURS channel to 2 watts. Radios that are type accepted for MURS are licensed by rule or license-free, which means an FCC license is not required to transmit on the MURS channels.
NOAA Weather Alerts
Radios that support NOAA weather alerts will pro-actively alert you when a weather alert, such as a severe weather warning, is issued in your area. This means that if you are concerned about possible severe weather, you don't have to continually monitor a weather channel. Instead you can rest assured that your radio will alert you when an alert is issued. NOTE: Weather alerts are not yet supported by all NOAA stations.
Noise Blanker
Radios with this feature have the ability to block certain frequencies to better identify and filter out interference.
Noise Canceling Microphone
Some radios are equipped with a noise canceling microphone to provide clear communication when used in a noisy environment.
Noise Filtering
The noise filtering feature reduces unwanted noise. Many models accomplish this by shutting off weak transmissions, thus eliminating unwanted noise due to terrain and conditions. For some other manufacturers, turning this feature on means that the radio only receives transmissions from other radios by the same manufacturer with this feature enabled.
NXDN™ Digital
NXDN™ is a Common Air Interface (CAI) based protocol used by digital mobile radios.
Optional Board
Radios that support an Optional Board include an expansion slot inside the radio for a plug-in module or circuit board with additional features and functionality, such as GPS capability, an upgrade to digital communications or voice scrambling.
Out-of-Range Alert
The Out-of Range alert feature lets you know when two radios of a group equipped with this feature are within range. When the Out-of-Range feature is active, your radio will automatically transmit a code at specific intervals in an attempt to handshake with the other radio. If the code is received, the other radio will send a confirmation code.
P25
Project 25 (P25) is a standard for the manufacture of digital 2-way wireless communications devices that are interoperable. P25 was created by and for professionals in public safety and is managed by the Telecommunications Industry Association (TIA Mobile and Personal Private Radio Standards Committee TR-8). To comply with P25 standards, radio equipment must meet a minimum set of requirements to be interoperable with other P25 devices. This allows users of different systems to contact one another directly via radio for public safety communications.
PC Configurable
PC configurable radios, more commonly referred to as PC Programmable, can be connected to a computer and configured or programmed with a software application provided by the manufacturer. Many business radios are authorized by the manufacturer to be programmed only by the radio dealer, however a few brands and models are allowed to be programmed by the end user as well. Most amateur radios can be programmed by the end user, and an increasing number of newer GMRS radios are also user programmable. Programming software usually provides a user friendly way to adjust radio settings or change user selectable frequencies.
Plug-In Charge Capable
Two way radios that are plug-in charge capable have a port where you can plug in a charger. This is similar to how most wireless phones are charged.
Power Selectable
The power selectable feature allows you to switch between high and low power modes on the radio. Low power mode would reduce the range of your two way radio, however there are situations in which switching to a lower power could be advantageous. For instance, if everyone in your group is operating within close range, you may prefer to operate in low power mode and reduce your range outside the radius of your group to minimize eavesdropping from others who may be listening in or monitoring your channel or frequency.
Power-On Password
The radio requires a password when powered on to prevent unauthorized users from access.
Priority Scan
The radio allows you to set a preferred frequency when scanning.
Privacy Codes
Also known as Interference Eliminator codes, Private Line (PL) or Digital Private Line (DPL) codes, QT codes, channel guard, or subchannels, Privacy Codes help reduce interference by filering out transmissions from other parties using the same channel or frequency.
Privacy Codes are divided into two distinct types, Continuous Tone Coded Squelch System (CTCSS) tones and Digital Coded Squelch (DCS) codes. CTCSS is an analog tone system and DCS is a digital code system.
While they are commonly called "privacy codes" they do not make conversations more private. They serve more as filters to eliminate interference from unwanted transmissions and aid in finding a clear channel.
This is an extremely useful feature. In places where many people are using two way radios, such as sporting events or theme parks, it would be very difficult to find a channel that wasn't always being used or monitored if only a few channels were available. Privacy codes make it possible for you to take your two way radio to high traffic areas and still be able to communicate with your group with minimal interference from others.
Programmable Buttons
A programmable button is a button on the radio that you can program or assign to perform a user specific function.
Programmable LED Alert
This feature allows the user to configure or program the LED indicator to light up or flash for specific alerts.
Public Address Capability (PA Capability)
This feature allows you to use the radio as a public address system through an aftermarket external speaker.
Quick Disconnect
This feature allows quick disconnection of the cable. Usually found on audio accessory components.
Radio Check Diagnostic
Radios with this feature have a diagnostic mode to test functions such as antenna condition, battery voltage and RF power.
Range
Range is defined as the farthest distance a radio can transmit and/or receive a radio signal. It is important to be aware that the range advertised by two way radio manufacturers for a specific make or model is always the maximum range that the radio will get under ideal or perfect conditions.
Radios operate by line-of-sight, and anything that can potentially interfere with or block it will affect their range. Factors that can affect the range include, but are not limited to, the type of radio signal, obstructions, terrain, the distance to the horizon, the type and height of the antenna, power (wattage), and atmospheric conditions.
Range Extender
This is the opposite of the Noise Filter feature. When the range extender feature is turned on, your radio will receive even very weak transmissions. This may result in unwanted noise, but will extend the range of your two way radio.
Rechargeable Battery Included
Some two way radios include rechargeable batteries. If you plan to use your radio frequently, upgrading to a model that includes rechargeable batteries will pay for itself in no time!
Repeater Capable
A repeater capable radio has the ability to have the transmit (TX) and receive (RX) frequencies for a single channel set to different values. This allows the radio to communicate through a repeater - a device that amplifies a radio signal, greatly increasing range.
Reverse Frequency
Radios with a Reverse Frequency feature allow the operator to swap the transmit and receive frequencies on an active channel. The transmit and receive frequencies are exchanged or reversed, allowing the radio to transmit on the receive frequency and receive on the transmit frequency, This feature is useful for checking if you are within simplex range of other radios communicating through a repeater before activating the Talk Around feature.
Reset
This feature allows you to reset the radio to its original factory settings.
Rewind-Say-Again™ Digital Voice
This is a feature that is almost exclusive to some higher end Cobra consumer radios. It allows you to playback the last 20 seconds of an incoming transmission, transmit saved messages, and record messages to yourself.
RF Meter
An RF meter monitors your RF setting and displays it visually, either in the form of an analog meter, LED bar or digital graphic.
Ring Tones
A ring tone is a tone or series of tones played to signal an incoming call.
S.A.M.E. Technology
S.A.M.E. technology allows for specific alerts to be sent as coded messages as part of a NOAA broadcast. A weather radio that is capable of decoding SAME messages can proactively alert to specific severe weather or civil emergency situations. A location is also coded into the message, allowing SAME capable weather radios to filter out warnings that do not apply to the owner's general area.
The following are just a few of the 60+ possible emergency announcements: tornado alert, child abduction, immediate evacuation, hazardous material warning, local area emergency, biological hazard warning, civil emergency, contagious disease warning, food contamination warning, power plant warning, industrial fire warning.
Scan Channel Delete
Radios with this feature allow you to remove a specific channel from a scan. This can be very useful if you need to perform a scan, but there are channels with activity that you know you are not interested in.
Shared Channels
These are channels that are shared between more than one radio service. For instance, the Family Radio Service (FRS) and The General Mobile Radio Service (GMRS) share the same 22 channels and frequencies assigned to them by the FCC.
Signal Strength Indicator
A signal strength indicator will measure your incoming and outgoing transmissions and display them visually, either in the form of an analog meter, LED bar or digital graphic.
Silent Mode
In silent mode, the radio will indicate an incoming transmission without making an audible alert of any kind. Typically, the display will flash several times to indicate the incoming transmission. This is a great feature for hunters, where a noise may be disruptive.
SOS
Radios with this feature can transmit an SOS alarm to other stations on the same channel.
Sound Tracker Systerm
This is a noise reduction feature built into some Cobra branded rados that helps to maintain a strong, clear signal.
Special Edition
Radios designated as Special Edition or Limited Edition versions have styling or features not included in the standard model of the same series.
SSB Channels
SSB or Single Side Band channels are the upper and lower halves of the normal 40 CB channels. This allows you to mix two different frequencies together to get a custom frequency, like mixing colors together.
SSB Output Power
SSB or Single Side Band Output Power is the amount of wattage that the CB radio can transmit on while set to a Single Side Band channel.
Stopwatch
Some two way radios have a stopwatch feature. A stopwatch displays the amount of time between when it was started and when it was stopped.
Stun/Kill/Revive
Stun and Kill disables a radio over the air and Revive restores the disabled radio.
Submersible
Radios that are capable of full immersion in water for a specified depth and period of time are considered submersible. If the radio is rated either JIS7 or IP67, it means it has been tested to be waterproof and submersible in up to to 3.3 ft (1 m) of water for up to 30 minutes.
SWR Calibration
SWR or Standing Wave Ratio Calibration lets you calibrate the antenna of your radio for the best reception. The lower the ratio, the better performance you will get. A 1.1:1 ratio is the best, but 1.5:1 is easier to achieve. Many CB radios are equipped with an SWR Calibration Meter to monitor the effects of the SWR calibration.
SWR Calibration Meter
Radios equipped with an SWR Calibration Meter allow you to see the effects of the SWR or Standing Wave Ratio calibration to better enhance your ability to fine tune it.
Tactile Controls
Radios with tactile controls have buttons, knobs and/or switches that are designed or shaped in such a way that you can tell how they are adjusted without looking at them, typically with the use of fins and flats.
Talk Around
The talk around function sets the transmit and receive frequencies to the same frequency for communicating transceiver-to-transceiver. This allows the radio to bypass or "talk around" a repeater using its output frequency to communicate radio-to-radio via simplex.
Talk Back
The Talk Back feature allows you to monitor your own voice transmission by hearing it back through the radio speaker.
Talk Confirmation Tone
The Talk Confirmation Tone is often called a Roger Beep. When this feature is activated, a tone is transmitted to the listener after a transmission. This alerts the listener that you are finished, and that it is their turn to talk.
TDMA
TDMA (Time Division Multiple Access) protocol divides a digital signal to allow multiple users to share the same frequency. TDMA offers power and spectrum efficiency at low cost.
Text Messaging
This feature allows you to send SMS text messages to other people in the group.
Text-To-Speech Conversion
Radios with this feature can convert incoming text messages to speech. This feature may require a third party app.
Timeout Timer
The Timeout Timer feature limits the amount of time the radio can transmit. If the PTT or "TALK" button is held for a longer period of time than the period for which the timer was set, the radio will automatically stop transmitting. It is intended to prevent overtaxing the radio and to save battery life.
Transmit Inhibit
Transmit Inhibit disables the radio from transmitting, essentially putting it in "receive only" mode. This can be useful if the radio is in a situation such as a potentially hazardous environment where an erroneous or accidental rf transmission could increase the risk of danger or harm.
Transmit Power
The transmit power of a two way radio is measured in watts and is a contributing factor in determining the range of a radio. Generally the more watts of transmit power, the greater the range of the radio. The FCC limits the transmit power of a radio according the rules of each radio service.
Transmit/Receive Indicator
The transmit and receive indicator provides visual notification when the radio actively sends or receives a transmission. This usually takes the form of a two-color LED that glows one color (usually red) for transmit and another color (usually green) for receive.
Tri Band
Radios with Tri Band capability can transmit and receive on three radio bands. An example of this is a radio that can operate on 70 cm UHF, 1.5 meter VHF and 2 meter VHF radio bands.
Trunking
Trunking is system that uses a pool of frequencies to share a minimum number of channels between a large number of users. Trunking is commonly used for two-way radio communications by government agencies, municipalities and emergency response services who share the same frequency spectrum. Users are assigned to "talkgroups" instead of individual frequencies. Trunking allows the available channels and bandwidth to be managed more effectively.
Two Tone and Five Tone Codes
Radios that support Two-Tone and Five-Tone codes are capable of MDC1200 signaling using ANI codes with either two or five tones. These tones can be used to send alarms or activate alerts on other radios that support them.
UHF Frequencies
Business, commercial and consumer two way radios that support UHF frequencies will operate on frequencies in the 400 MHz - 512 MHz range. UHF radios are more popular than VHF because they offer better range inside steel or concrete structures.
USB Port
Radios with a USB port can be charged using a standard USB cable. These cables are extremely common. Chances are you already have one for your cell phone, tablet, or other small electronic device. USB cables are widely available to connect to a PC, or to plug into an AC adapter or DC vehicle port.
User Selectable Frequencies
Two way radios with user selectable frequencies separate the concept of channels from frequencies and allow the user to assign a channel number to a frequency from a built-in list. For example, a two channel business radio may support 56 frequencies. The user could go into a simple "programming mode" and assign channel 1 to any of the supported frequencies. This differs from a "dealer programmable" radio, which typically could be set to a relatively limitless number of frequencies but would be unchangeable by the end user.
VHF Frequencies
Business, commercial and consumer two way radios that support VHF frequencies will typically operate on frequencies in the 136 MHz - 174 MHz range. VHF radios work best when used outdoors or in and around wood structures.
Vibrate Alert
Two way radios with the vibrate alert feature have the ability to vibrate to alert you that you are receiving a message. This is very useful in noisy environments where it would be difficult to hear a call tone or a message.
Voice Lock
The Voice Lock feature allows you to fine tune sideband transmissions to clarify distorted voice communications.
Voice Prompts
The radio actually talks to you in a human-like voice. You will hear the prompt spoken in plain English.
Voice Recorder
The radio is capable of recording an incoming message for a specified period of time when activated.
Voice Scramble
Radios equipped with a voice scramble feature can garble your transmissions, allowing you to have conversations that are more private and secure. In order to use the voice scramble feature, all members of your group must have radios that support it. Voice scramble does not guarantee secrecy, as someone with a similar radio could hear your conversations, but it does add an extra layer of privacy.
Voting Mode Scanning
The voting mode scanning feature detects the signal strength level of repeater stations and automatically selects the strongest station. This is useful for roaming between 2 or more repeater sites. Once you program the voting mode to a memory zone, you can easily start voting mode operation by changing the zone setting.
VOX
Radios that support the Voice Activated Transmit (VOX) feature allow you to use your two way radio "hands-free". The radio will automatically begin transmitting when you speak.
Water Resistant
Water resistant two way radios are better suited for use in environments where they may get wet.
Weather Channels
Radios that support this feature can tune into broadcasts by the NOAA Weather Radio and Environment Canada Weather Radio. Most radios that will allow you to listen to weather channels also have the ability to alert you automatically to emergency weather broadcasts.
This feature requires that NOAA or Environment Canada service be available in your area. Check with your local weather office to verify that this service is available.
Weather Scan
The weather scan feature automatically scans all NOAA channels on a weather radio and stops on an active channel. When the channel is inactive for ten seconds, the radio will continue to scan.
