Glossary of Radio Terms

2X Signal Booster

Option that offers up to double the efficiency/range of a portable Travelers Information Station’s antenna, allowing the signal to have additional the intensity at a given distance. Functions with upper-band (typically 1610-1700) antennas only. Recommended for any operator in a challenging environment that requires maximum signal intensity to cut through woods, buildings and obstructions. (Note: local government licensees must seek a waiver of FCC Part 90 TIS rules to allow signal intensity above the standard 2.0 mV/m limitation.)

AAIRO

See American Association of Information Radio Operators.

Absorbant Glass Mat (AGM)

Sealed lead-acid battery designed to reduce weight and improve reliability. The sulfuric acid is absorbed by a very fine fiberglass mat, making the battery spill-proof, which enables shipment without hazardous material restrictions. When compared to conventional flooded-lead-acid batteries, AGM has these advantages: it is high-current capable, maintenance-free, with a long life, low temperature operation, light weight, longer storage time between charges, the ability to deep-cycle, vibration resistan5. AGM disadvantages include: it is sensitive to heat and to overcharging.

AC

See Alternating Current.

AEL

See Authorized Equipment List.

AGM

See Absorbant Glass Mat.

Ah

See Amp Hour.

ALERT AM Emergency Advisory Radio System

Fixed Emergency Advisory Radio and Highway Advisory Radio systems from Information Station Specialists used primarily for notifying motorists of emergencies and instructing them how to proceed. The system is outfitted with NOAA's Emergency Alert System 'all hazard' warning interruptions targeted to specific counties; multiple power and programming options, such as GPS synchronization for multi-station groupings, battery backup to continue operation during power outages and a large cabinet for flexibility. FCC-licensed. Range 25-75 square miles. Used in combination with Flashing ALERT Signs. See the ALERT AM webpage.

All-Hazard Warning System

See Emergency Alert System.

Alternating Current (AC)

A flow of electric charge that periodically reverses direction, often distinguished from Direct Current (DC). The usual waveform of an AC power circuit is a sine wave, such as audio and radio signals carried on electrical wires. An important goal is often recovery of encoded (or modulated) information onto the AC signal.

AM

See Amplitude Modulation.

American Association of Information Radio Operators (AAIRO)

A nonprofit association, founded in 2008, of operators, licensees and interested others from public agencies nationwide who manage Travelers Information Stations (TIS and HAR) to broadcast to motorists public safety/service messages. See the group's mission and more at AAIRO's website.

Amp

Unit of electric current.

Amp Hour (Ah)

Unit of electric charge equal to the charge transferred by a steady current of one ampere flowing for one hour, frequently used in measuring batteries. It is not a unit of energy. In a battery system, for example, accurate calculation of the energy delivered requires integration of the power delivered (product of instantaneous voltage and instantaneous current) over the discharge interval. Generally, the battery voltage varies during discharge; an average value or nominal value may be used to approximate the integration of power.

Amplitude Modulation (AM)

A method of radio modulation that varies carrier wave amplitude. Used by Travelers Information Stations (TIS and HAR) and AM broadcast stations in the United States. It works by varying the strength (amplitude) of the carrier in proportion to the waveform being sent, which contrasts with Frequency Modulation (FM), where the frequency of the carrier signal is varied. AM frequency range is 530 to 1710 kHz.

AM Radio Antennas

See ANXX and AN2X AM Radio Antennas (immediately below). See also HPR.0990 AM Radio High Performance Antenna.

AMReady Broadcast Components

Licensed AM broadcasters can obtain specialized components to keep their stations on the air. Use of these products by licensed broadcasters may be covered by adherence to FCC Part 73/1560 Rules. Included are transmitters, antennas, antenna support and accessories and groundplanes and rods. See AMReady Broadcast Components.

AN2X AM Radio Antenna

With a much longer basepipe and more efficiency than ANXX (below), AN2X produces a signal intensity of 2.0 mV/m at 1.5 km, the FCC maximum field level. That signal is typically strong enough to erect signs for alerting listeners at 3 to 5 miles. The antenna may be mounted atop a square or round pole of wood, metal or fiberglass. This antenna system is packaged with a factory-wired groundplane, pole mounts and insulators, a cabinet-protected lightning arrestor system and ground bus for lightning dissipation and groundplane connection. See the webpage. See also an antenna comparison chart.

ANXX AM Radio Antenna

Produces a signal intensity of 2.0 mV/m at 1.5 km, the FCC maximum field level. That signal is typically strong enough to erect signs for alerting listeners at 3 to 5 miles. The antenna may be mounted atop a square or round pole of wood, metal or fiberglass. This antenna system is packaged with a factory-wired groundplane, pole mounts and insulators, a cabinet-protected lightning arrestor system and ground bus for lightning dissipation and groundplane connection. See the webpage. See also an antenna comparison chart.

AP.55 Digital Message Player

In production at Information Station Specialists from 1990-2007. See current Digital Audio Management Systems.

AP.6000 Digital Message Player

In production at Information Station Specialists from c. 1997 to c 2015. See current Digital Audio Management Systems.

Audio Control Systems

See webpage.

Audio Filter HQ 5.0

Passive design requiring no power, commonly added to portable radio stations such as RadioSTAT and VoiceStar and those with cabinets in which equipment is mounted to a back panel, such as legacy Information Stations. Can be added to any Information Station Specialists' radio station, however. Requires that the transmitter's internal 3000 Hz filter be disabled in conjunction with the addition of the filter. Exclusively permitted by the FCC for operation as part of Information Station Specialists' TR.6000 Transmitter System.

Audio Processor HQ 5.2

Active device requiring power that increases broadcast quality, i.e., adds compression and limiting, thereby boosting loudness and functional range of broadcasts. Commonly used with ALERT AM and new Information Stations. Requires that the transmitter's internal 3000 Hz filter be disabled in conjunction with the addition of the processor. Exclusively permitted by the FCC for operation as part of Information Station Specialists' TR.6000 Transmitter System.

Authorized Equipment List (AEL)

A list of approved equipment types allowed under FEMA’s preparedness grant programs. The intended audience of this tool is emergency managers, first responders, and other homeland security professionals. The list consists of 21 equipment categories divided into categories, sub-categories and then individual equipment items. There are no commercially available products listed; it only consists of equipment types. See also Standardized Equipment List.

Broadcast Station

A conventional radio station authorized by the FCC under Part 73 Rules to broadcast music, news and other programming on AM or FM to the community to which it is licensed. Broadcast stations in the United Stations operate at powers of up to 50,000 watts on AM on frequencies 540-1700 and up to 330,000 watts on FM frequencies 88.1 to 107.9. See Travelers Information Station differences.

Call Sign

Federal Communications Commission Rules (Part 90) govern the licensing of Travelers Information Stations (TIS and HAR) issued to local government entities such as states, cities and counties. The Commission assigns 7-character call signs to all − 4 alpha letters, followed by 3 numbers.

Modern station call signs that are issued by the FCC begin with a “W” (though many years ago some were issued that started with a “K”). The next 3 letters and 3 numbers are sequential, based on when the Commission grants each license.

Although the Commission does not permit applicants to request specific call signs, in a few instances (when licensees indicated certain call signs were objectionable), the FCC granted changes.

The FCC requires that the full 7-character call sign be broadcast every 30 minutes (or more) in English. Sometimes station operators inadvertently drop off the three numbers of the call sign, probably because standard broadcast stations (licensed under FCC Part 73 Rules) don't have numbers in their call signs and have only three or four characters (WGN, WABC, etc.).

Travelers Information Stations operated by federal government agencies are licensed through the NTIA (National Telecommunication Information Agency) rather than the FCC and do not necessarily follow the same format. In some instances, these call signs might begin with a "K," have only three letters or no numbers.

Information Stations authorized by branches of the military are not issued call signs

CAP

See Common Alerting Protocol.

CCI

See Co-Channel Interference.

Co-Channel Interference (CCI)

Crosstalk from 2 different radio transmitters using the same frequency. There can be several causes, for example, cellular mobile networks, adverse weather conditions, poor frequency planning, overly crowded radio spectrum, daytime versus nighttime, signal cancellation.

Common Alerting Protocol (CAP)

An XML-based data format for exchanging public warnings and emergencies among alerting technologies. CAP allows a warning message to be consistently disseminated simultaneously over many warning systems to many applications. CAP increases warning effectiveness and simplifies the task of activating a warning for responsible officials. See also Emergency Alert System.

Components

See AMReady Broadcast Components.

Contruction Notification

After an information radio station is on-air, the FCC requires most licensees to construct their authorized system or meet specific coverage requirements within a given time period and to notify the FCC that the requirement was met. This construction/coverage time period varies depending on the radio service in which the license is held. If a licensee fails to construct a frequency, fails to construct a location, fails to construct an entire license, fails to meet a coverage requirement or fails to file a Request for Extension, the frequency, location, or license terminates automatically as of a given deadline. See also Special Temporary Authority.

Continuous Tone Coded Squelch System (CTCSS)

A circuit used to reduce the annoyance of listening to other users on a shared communication channel.

CTCSS

See Continuous Tone Coded Squelch System.

DC

See Direct Current.

Digital Audio Management Systems

See Audio Control Methods for Information Radio Systems.

Digital Message Players

See Audio Control Methods for Information Radio Systems.

Direct Current (DC)

The unidirectional flow of electric charge produced by sources such as batteries and solar cells. The electric current flows in a constant direction, distinguishing it from Alternating Current.

DN.1201 Program Mixer for Live and Multi-Source Live-Feed Itegration and Level Management

Introduced in 2020. Used in the ALERT AM System.

DTMF

See Dual-Tone Multi-Frequency Signaling.

Dual-Tone Multi-Frequency Signaling (DTMF)

Used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communication devices and the switching center. The version of DTMF developed by Western Electric that is used in push-button telephones for tone dialing is known as "Touch Tone," a registered trademark of Bell Telephone.

EAS

See Emergency Alert System.

Electromagnetic Interference (EMI)

Also called Radio Frequency Interference (RFI) when associated with radio systems, EMI is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct or otherwise degrade or limit the effective performance of the circuit. The source may be any object, artificial or natural that carries rapidly changing electrical currents, such as an electrical circuit, the sun or Northern Lights. EMI can intentionally be used for radio jamming or can occur as a result of spurious emissions through intermodulation products.

Emergency Advisory Radio Station

Specially outfitted Travelers Information Station used primarily to broadcast emergency instructions to motorists before, during and after crises. The ALERT AM fixed system, RadioSTAT hand-portable station and VoiceStar trailer-mounted stations are three primary examples from Information Station Specialists.

Emergency Alert System (EAS)

Jointly coordinated by the Federal Emergency Management Agency, the Federal Communications Commission (FCC), and the National Weather Service, EAS is a national warning system, begun in 1997. The EAS system was preceded by the Emergency Broadcast System begun after World War II to enable the US President to speak to the entire country in fewer than 10 minutes during national emergencies. The federal aspect of the EAS system has been tested but has never activated. The National Weather Service’s part of the system is designed to alert the public during local weather emergencies, such as tornadoes and flash floods. It is in operation on a daily basis throughout the United States.

EAS regulations and standards are governed by the Public Safety and Homeland Security Bureau of the FCC. Each state and several territories have their own EAS plan; and EAS has become part of IPAWS – the Integrated Public Alert and Warning System, a program of FEMA. Digital EAS codes make it possible to target warnings for automatic broadcast to citizens through NOAA weather radio receivers programmed through Specific Area Message Encoding (SAME) that comes standard on Information Station Specialists' ALERT AM system and as an option on the portable VoiceStar radio system.

Emergency Notification Systems (ENS)

The one-way dissemination or broadcast of messages to one or many groups of people, alerting them about pending or existing emergencies. Many local governments and organizations that hold large, public events adopt emergency notification systems to be able to notify large groups of people in the event of an emergency. Most major telecommunications providers offer Public Safety Answering Points (PSAPs) access to their subscriber data (in the areas serviced by the PSAP) in order to facilitate the effective use of one-way emergency notifications.

Emergency Override Message

A recorded message, message format or live feed designed to take precedence in an emergency and lock out secondary messages from broadcasting. Example: when the National Weather Service issues a tornado warning, day-to-day messages on the radio station are interrupted and locked out while being superseded by the NWS warning during the time that it is pertinent. See also Emergency Advisory Radio Station.

EMI

See Electromagnetic Interference.

ENcast Emergency Notification Broadcast System

Information Station Specialists option, introduced in 2014 and discontinued in 2021, to broadcast text-based emergency notifications over a Travelers Information Station automatically.

ENS

See Emergency Notification Systems.

EventCAST Radio Stations and LED Signs

Portable radio station and sign purchase/rental service from Information Station Specialists, introduced in 2017 as a replacement service formerly called RadioExpress. Designed for event broadcasting, signal testing and other temporary applications, EventCAST offers complete, portable AM band Travelers Information Stations with a 3-5 mile radius range from the antenna center point (25-75 square miles). Each station's weatherproof design with quick-erect antenna system allow setup in almost any environment. Portable LED changeable message signs with various mounting styles are part of the service. See the EventCAST webpage.

Extended Range Outdoor Antenna and Tuner RE 2.5

Increases the effective signal range of an existing InfOspot / Talking House (i A.M. Radio) Transmitter from hundreds to potentially thousands of feet by providing a simple, professional means of installing the transmitting antenna outdoors – typically on a roof or atop a support pole/tower. The Talking House (i A.M. Radio) line of products is unique as the only such license-free system certified under FCC Part 15.219 with coaxial cable in its approved design. See specifications.

Exterior Dimensions

Length, width and height measured on the outside surfaces of a container, such as a box, enclosure, trailer, etc., used to determine the dimensions and volume of same. See also Interior Dimensions.

FAS.6000 Flashing Beacons and Controller

Allows an operator to turn on or off a pair of highway sign of flashing amber beacons, through wireless means, without the need to compromise the AM broadcast signal the sign might announce. The FAS.6000 controller includes a solar-powered collection-and-storage system, receiver, two amber 8" or 12" LED flashing beacons, weatherproof enclosure, mounts, wiring and instructions. Wireless control methods vary. Typically used on roads of 55 miles per hour and higher. See the FAS.6000 webpage.

FASTrack Quick-Erect Portable Sign

FHWA/NFPA-approved for use at emergency scenes, one-piece FASTrack signs are portable and quick to assemble during emergencies. They are available with custom sign text and optional text overlays. See the FASTrack webpage.

FCC

See Federal Communications Commission.

FCC TIS Rules

See Part 90 TIS Rules.

Filter, HQ 5.0 Audio

See HQ 5.0 Audio Filter.

Federal Communications Commission (FCC)

An independent US federal agency, created by Congressional statute to regulate interstate and international communications by radio, television, wire, satellite, and cable in all 50 states, the District of Columbia and US territories. The FCC works toward goals in the areas of broadband, competition, the spectrum, the media, public safety and homeland security. See also FCC rules for Travelers' Information Stations.

Flashing ALERT Sign

Wireless-controlled, solar-powered beacon signs from Information Station Specialists that may be triggered remotely to advise motorists to tune to a special radio signal for information or to take a specific action in any public safety situation. See the Flashing ALERT Sign webpage.

Flashing Beacons and Controller

See FAS.6000 Flashing Beacons and Controller and Flashing ALERT Sign.

FlexPlane Factory-Assembled Groundplane

Previously patented as PowerPlanes, Information Station Specialists' groundplanes are composed of multiple copper wire ground radials bonded with a heavy gauge copper lead wire. The radial wires vary in length, gauge and flexibility, depending upon each application. See a TechTalk article, entitled "Why Antenna Grounding Is Important."

FM

See Frequency Modulation.

Forward Power (FP)

A standing wave on a transmission line can be composed of 2 traveling waves, 1 moving toward the load (the forward wave) and 1 moving in the opposite direction (reflected wave).

Free-Standing AM Radio Antenna System with Tower SS.3000

Produces a signal intensity, which, with FCC allowance, is higher than possible using the standard ANXX AM Radio Antenna. At 10 watts, the signal intensity may be 2.0 mV/m at 2.25 miles, producing a sign-able range of 8 to 12 miles. (Note: Special FCC allowance for increased signal intensity is required.) The Free-Standing Antenna System's 49-foot antenna/tower, antenna tuner and 30-foot groundplane are designed to be ground-mounted in an unobstructed area approximately 100 feet in radius for maximum propagation. A concrete pad supports the antenna, tower and tuner. See the webpage. See also an antenna comparison chart.

Frequency Modulation (FM)

A method of radio modulation in which the frequency of the carrier wave are varied. FM frequency range is 88 to 108 MHz. See also amplitude modulation.

GFCI

See Ground Fault Circuit Interrupter.

GFI

See Ground Fault Interrupt.

Global Positioning System (GPS)

A space-based satellite navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.

GPS

See Global Positioning System.

GPS Frequency Stabilization

A method of synchronizing the carrier and/or the audio of multiple (typically overlapping) Information Radio signals in order to reduce interstation interference effects.

Ground Fault Circuit Interrupter (GFCI)

Device to quickly disconnect current to prevent serious harm from an ongoing electric shock. Known variously as "Ground Fault Interrupter," "residual-current device," "residual-current circuit breaker," "appliance leakage current interrupter."

Ground Fault Interrupter (GFI)

GFIs compare currents leaving hot conductors to currents returning on neutral conductors, disconnecting circuits if that difference exceeds 4-6 milliamps. Required in the US and Canada for potentially wet locations, GFIs are cheaper than Ground Fault Circuit Interrupt (GFCI) circuit breakers and can be wired to feed additional downstream outlets so that putting one GFCI receptacle in a circuit protects all downstream plugs, lights and switches. GFIs are recommended for power tool outlets.

Groundplane

Device used to provide horizontally oriented grounding of Travelers Information Station antenna systems. The more robust the grounding, the more efficient the antenna system and the stronger the resulting signal ot a given transmitter wattage. The FlexPlane Preassembled Groundplane is one example. See why groundplanes are important, how they're made and installed on this TechTalk webpage.

Groundrod

For installations where vertical grounding is required but the antenna must be mounted on an existing pole or structure, an Information Station Specialists Unirod may be employed. The Unirod is from 10 to 40 feet in length (longer Unirods for long wavelength frequencies) and is augured into the earth beneath the antenna pole, installed with a highly conductive soil backfill. Unirods are also recommended when the most efficient possible grounding method is required. See also Groundplane and Vertical Profile Antenna Support and Grounding System and a TechTalk article, entitled "Why Antenna Grounding is Important, How It Works & Is Installed."

HAR

See Highway Advisory Radio.

HearMoreInfo StreamCAST

A simple, affordable Information Station Specialists service to deliver timely, targeted high quality audio directly to smartphones, tablets, laptops and PCs. StreamCASTs allow Internet linking of audiences to a continuous program, such as the broadcast program of a Travelers Information Station or the play-by-play of a live event. StreamCASTs may be full production, including music, and may be sponsored, making the service revenue-neutral – or even profitable for operators.

Hertz (Hz)

Unit of frequency in the International System of Units (SI) defined as 1 cycle per second, named for Heinrich Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves. See also Megahertz.

Heterodyne

Interstation interference caused when unsynchronized co-channel (same frequency) radio station signals overlap and interact.

High Performance AM Radio Antenna HPR.0990

A High Performance Antenna introduced by Information Station Specialists in 2019. It offers the ability to establish an AM broadcast signal capable of reaching greater distances than before possible with antennas of similar design. Twice as efficient as comparable antennas, this high capacity antenna is compact and light-weight, making it easy to ship and install. As a higher wattage antenna (e.g., part of the RadioSAFE System), an emergency Special Temporary Authority (STA) from the FCC is required. See the HPR.0990 webpage. See also an antenna comparison chart.

Highway Advisory Radio (HAR)

Term Departments of Transportations (DOT) commonly use for Travelers Information Stations in place along highways for traffic-control. The ALERT AM fixed and VoiceStar portable stations are prime examples of Highway Advisory Radio Systems.

HPR.0990

See High Performance Antenna.

HQ 5.0 Audio Filter

See Audio Filter . . .

HQ 5.1 Audio Processor
See Audio Processor . . .

IAB

See InterAgency Board.

IAB Interactive Standardized Equipment List

See Standardized Equipment List.

i A.M. Radio Enhanced Audio Talking House Transmittter

See InfOspot AM Radio Transmitter System.

InfoMAX License-Free Radio Station

Early trade name for InfOspot License-Free Radio Station.

InfoRadio Format

Professional broadcast recording service from Information Station Specialists. See Professional Recording Services webpage.

Information Radio Station

General term for Travelers' Information Station or Highway Advisory Radio Station.

Information Station IP or USB
Fixed Travelers Information Station used primarily for broadcasting general information to motorists. May be used in emergencies. Versions include “IP” – operable via network – and “USB” – with a port for a flash drive. FCC-licensed. Typical coverage: 25-75 square miles. Used in combination with Flashing ALERT Signs. See the Information Station webpage.

Information Station Specialists (ISS)

The USA's best known source for Travelers Information Stations (TIS and HAR), advisory signs and the specialized services required to transmit spoken messages to motorists − the only such source providing products entirely made in America. See What's Special about the Specialists webpage.

InfOspot AM Radio Transmitter System

Formerly known as InfoMAX, Talking House and i A.M. Radio. Range: up to 1/2-mile. Can be portable or stationary. No license required per FCC rules Part 15.221. See InfOspot webpage. See also the Range Extender option.

Integrated Public Alert Warning System (IPAWS)

An architecture that unifies the United States' Emergency Alert System, National Warning System, Wireless Emergency Alerts, and NOAA Weather Radio, under a single platform.

Intelligent Transportation Systems (ITS)

Technology along US highways that allows motorists to be better informed to make safer and smarter use of transport networks. ALERT AM fixed and VoiceStar portable radio stations offered by Information Station Specialists operate as part of Intelligent Transportation networks as do FAS.6000 flashing sign controllers and beacons.

InterAgency Board (IAB)

Under the auspices of the US Attorney General, in 1998, the InterAgency Board for Equipment Standardization and Interoperability was founded. Its work is influenced by officials from the Departments of Defense and Justice, with participation from local, state and federal government emergency management agencies. The group's mission is to strengthen the nation's ability to prepare for and respond to emergencies by developing a common language, for example, the Standardized Equipment List, and common methods of practice.

Interior Dimensions

Length, width and height measured inside a container, such as a box, enclosure, trailer. etc., used to determine interior volume and how smaller items can best be arranged within. See also Exterior Dimensions.

IP.8 Digital Message Player

Discontinued in 2020. See current Audio Management Systems.

IP.76 Digital Message Player

In production from 2003-2020. See current Audio Management Systems.

IPAWS

See Integrated Public Alert Warning System.

ISS

See Information Station Specialists.

ITS

See Intelligent Transportation System.

ITS.6000 Highway Advisory Radio Network

Fixed Highway Advisory Radio Network with related flashing beacon accessories from Information Station Specialists, used by Departments of Transportation as part of ITS projects. Rolled into the ALERT AM line in 2021.

Kilo Ampere (kAmp)

A measurement equal to 1000 amperes (100 amps) of current in an electrical circuit.

Kilohertz (kHz)

The term “hertz” is equivalent to “cycles per second.” A kilohertz is 1000 cycles per second. The frequency of a Travelers Information Station is measured in kilohertz, with 530 kHz being the lowest frequency and 1710 kHz the highest.

Kilometer (km)

Metric unit of length equivalent to 1000 meters or 0.62137 miles.

kAmp

See Kilo Ampere.

kHz

See Kilohertz.

km

See Kilometer.

LED

See Light Emitting Diode.

Light Emitting Diode (LED)

Semiconductor device that emits visible light when an electric current passes through it. The light is not particularly bright, but in most LEDs, it is monochromatic, occurring at a single wavelength.

LIGHTNING LED Message Sign

Affordable and easy to set up, this portable changeable message sign, offered by Information Station Specialists from 2016-21, programed via a wireless remote control and displayed messages indoors or out. Operates up to 30 hours on a single battery charge, indefinitely on land power. Displayed new messages instantly. Stored hundreds for future use. Came with carrying case and mounting options.

LLIS-RKB

See Responders Knowledge Base.

Low Power AM (LPAM)

Descriptor often used for a Travelers Information Station.

Low Power FM (LPFM)

Non-commercial educational broadcast service, established by the FCC in 2000. Public safety agencies, may use Low Power FM Stations with special provisions and restrictions. Licenses may be requested during specific “filing windows” announced periodically by the FCC. LPFM stations have special licensing and programming requirements that make them less efficient for public safety and transportation agency applications. See the FCC's LPFM webpage.

LPAM

See See Low Power AM.

LPFM

See Low Power FM.

Ma

See Milliamp.

MATCHBOX Impedance Matching Transformer, The

See THEMATCHBOX.

Megahertz (MHz)

One million hertz, used to measure the frequency of radio

Message

Broadcast recordings or live voice transmissions.

MGR.021 Digital Audio Management System

See webpage. See also a comparison of audio managment systems.

MHz

See Megahertz.

Milliamp (Ma)

Unit of current equal to 1/1000 (10-3) of an Amp used to express flow rate of electric charge.

Millivolts per Meter (mV/m)

Unit of electromotive force equal to 1/1000 of a volt (the standard unit of potential difference and electromotive force). See also Volts of Alternating Current and Volts of Direct Current.

Milliwatts (mW)

Unit of power equal to 1,000th of a watt, output of electrical power.

Modulation

In electronics and telecommunications, the process of varying one or more properties of a periodic waveform, called the carrier signal, with a modulating signal that typically contains information to be transmitted. The information may take the form of audio or data.

Msg

See Message.

Multi-Modal

In communication, the employment of various tools to communicate a given message to the intended audiences.

mV/m

See Millivolts per Meter.

MW

See Megawatts.

National Electrical Manufacturers Association (NEMA)

Group of approximately 450 electrical equipment and medical imaging manufacturers in the US, founded in 1926, headquartered in Virginia. See website.

National Emergency Management Association (NEMA)

Nonprofit, nonpartisan association of emergency management and homeland security professionals, established in 1974, when state directors of emergency services first united to exchange information on common emergency management issues that threatened their constituencies. See website.

National Oceanic and Atmospheric Administration (NOAA)

Scientific agency within the US Department of Commerce focused on conditions of the oceans and the atmosphere. NOAA warns of dangerous weather (National Weather Service), charts seas and skies, guides use and protection of ocean and coastal resources and conducts research to improve understanding and stewardship of the environment. Go to NOAA's website.

National Telecommunication Information Agency (NTIA)

Executive Branch agency that advises the US President on telecommunication and information policy issues. NTIA tries to expand broadband Internet access and adoption in America and use of spectrum by all to ensure the Internet remains an engine for continued innovation and economic growth. NTIA licenses federally operated Travelers Information Stations (TIS and HAR). Visit the NTIA website for details.

National Weather Service (NWS)

Part of the federal government's National Oceanic and Atmospheric Administration (NOAA), tasked with providing forecasts, public warnings, and other products to organizations and the public for the purposes of protection, safety, and general information. This is done through a collection of national and regional centers and 122 local weather forecast offices. Go to the NWS website.

NEMA

See National Electrical Manufacturers Association or National Emergency Management Association.

NOAA

See National Oceanic and Atmospheric Administration.

NOAA All Hazard Alerts

See Emergency Alert System.

NTIA

See National Telecommunication Information Agency.

NWS

See National Weather Service.

NX8R Digital Message Player

Replaced by other Digital Audio Management Systems in 2022, the NX8R Digital Message Player was designed for fixed and portable Information Radio Systems, allowing operators to record up to 1,000 broadcast messages and store three hours of recordings in nonvolatile flash memory. No message (battery) backup was required. Additionally, NX8R provided 8 external contacts to initiate various message playlists, live audio segments and event sequences. NIt was a direct upgrade to earlier RAM-based digital message players (AP55 and IP8) with similar protocols and command sets, so relearning protocols was kept to a minimum for existing operators.

Part 15 FCC Rules

Stations approved by the FCC to operate license free. See a PDF of the Part 15.219 Rules. See also Part 15.221 Rules.

Part 90 FCC Rules

Rules originating in 1977 and updated in 2013 that govern the licensing and operation of Travelers Information Stations (TIS and HAR) in the United States. See a PDF of the Rules as updated in 2013 and the 2014 FCC TIS Compliance Guide.

PL

See Private Line.

Playlist

List of programmable broadcast recordings for a Travelers Information Station that normally play on the air in a repeating cycle. See also Digital Message Player.

Power Loss Notification Module

Travelers Information Station option that automatically dials up to 4 telephone numbers, including cell phones and pagers should loss of power be sensed.

PowerPlane Preassembled Groundplane

See FlexPlane

PowerSTAT Portable Energy Source

Introduced in 2011. Discontinued in 2017. A pure sine-wave AC inverter plus high capacity charger with hefty battery pack, all packaged in a weather-resistant portable case. Charged at any standard 120-volt AC power outlet. Provided pure, clean, energy, quietly. Approved for indoor use. Could stand alone or be employed as a power source for the RadioSTAT Portable Emergency Advisory Radio Station.

Private Line (PL)

In wired telephony, a tie-line service that involves dedicated circuits, private switching and/or predefined transmission paths, virtual or physical, that provide communication among specific locations. Most connect only two locations though they may be switched at either end or both. Some have multiple drop points.

Processor, HQ 5.2 Audio

See HQ 5.0 Audio Processor.

Radio Frequency (RF)

A rate of oscillation that corresponds to the frequency of radio waves and the alternating currents that carry radio signals. See Wikipedia details.

Radio Frequency Interference (RFI)

Disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source, degrading performance.

Radio Receivers for Cars - why they're all so different, a history

Visit this link, contributed by Lucas (via his teacher Noelle Bennett) of Learning Haven School. It explains why car radio receivers are all so different.

RadioExpress Portable Information Radio Service

Tradename revised to EventCAST in 2017. See the EventCAST webpage.

RadioSAFE Wide Area Emergency Radio Broadcast Systems

A community’s safety net – a key resiliency asset that can be called up during a major incident to direct citizens in evacuation, preservation of life and property and disaster recovery. RadioSAFE isystems are special radio stations that typically operates at low power (10 watts) under Travelers' Information Station rules – until required to go active in an emergency to advise the public. With the substitution of its high power transmitter, the system is capable of signal coverage that blankets an entire county or major city.RadioSAFE Wide Area Emergency Radio Broadcast Systems have the capability of staging hundreds of preplanned safety messages that can be selected locally or remotely at a moment’s notice and updated minute by minute. Programming can be performed at the station or remotely via telco or UHF/VHF transceiver or by LAN/WAN if optioned. Introduced by Information Station Specialists in 2019. See the RadioSAFE webpage. See also the HPR.0990 High Performance Antenna.

RadioSTAT Portable Emergency Advisory Radio Station

Compact, hand-portable Emergency Advisory Radio Station from Information Station Specialists that can be easily taken to an incident by land, sea or air. Housed in an easy-to-transport, high-impact, weather-resistant case, the station can operate from a fixed location when not required in the field. Controlled via flash drive or network. FCC-licensed. Range 25-75 square miles. Used in combination with FASTrack Signs.

Range Extender Outdoor Antenna and Tuner (RE 2.5)

Boosts range of InfOspot AM Radio Transmitter up to 2500 feet when mounted on a building, pole or tower. Its exclusive design allows a coaxial cable link between the transmitter and the antenna location, so the transmitter can stay indoors, safe from the elements and accessible. Comes with 25 feet of RG.6 Cable. May be ordered separately. First introduced in 2007 by another manufacturer; redesigned and reintroduced by Information Station Specialists in 2019. See Range Extender specifications.

REF

See Reflected Power.

Reflected Power (REF)

A standing wave on a transmission line can be composed of 2 traveling waves, 1 moving toward the load (the forward wave) and 1 moving in the opposite direction (reflected wave).

RF

See Radio Frequency.

RFI

See Radio Frequency Interference.

RKB

See Responders Knowledge Base.

RoadRunnR Portable Highway Advisory Radio System

Trailer-mounted portable Highway Advisory Radio System introduced by Information Station Specialists in 2000. See also VoiceStar.

SAME

See Specific Area Message Encoding.

SEL

See Standardized Equipment List.

Sequential, Two Tone

See Two-Tone Sequential.

Severe Storm Detector (SSD.20)

A personal storm sensing device. See the product overview.

Short Message Service

Short Messaging Service known as texting. For example, all Information Station Specialists fixed signage products may be triggered directly by any emergency notification system capable of sending messages in SMS text format. See Flashing ALERT Sign, FAS.6000 Flashing Beacons and Controller, and/or Stealth Sign.

Signal Booster

See 2X Signal Booster.

Signal Measurement Radio Receiver (SMR)

A portable radio receiver used for monitoring and measurement of AM radio signals. Displays AM signal levels so they may be documented. Used to comply with FCC Rules. See details on the SMR webpage.

Signs

See these fixed signs each: Flashing ALERT Sign, FAS.6000 Flashing Beacons and Controller, Stealth Sign fixed signs. See also these portable signs each: FASTrack Quick-Erect Sign, LIGHTNING LED Message Sign and VoiceStar.

Sines

In mathematics, the sine is a trigonometric function of an angle. A sine wave or sinusoid is a mathematical curve that describes the smooth repetitive oscillation of a radio wave.

Single Pole Double Throw (SPDT)

A switch that may be thrown in 2 directions, allowing current to pass to 2 different terminals, depending upon which way the throw is made. See also Single Pole Single Throw

Single Pole Single Throw (SPST)

A switch that makes contact between 2 discrete terminals, allowing electrical current to flow between them when the switch (throw) is closed and not when it is open. See also Single Pole Double Throw.

Skywave

A phenomenon on AM band channels caused by nighttime cooling in the ionosphere, prompting AM radio waves to reflect back to Earth at distant locations. See "What is skywave? The difference is Night and Day," TechTalk, 2013.

SMR

See Signal Measurement Radio Receiver.

SMS

See Short Message Service.

Special Temporary Authority (STA)

The authority granted to an applicant to operate a radio station or service for a limited time for a specified reason, such as an emergency, for testing or for restoration of communications or other short-term operations, whereby the applicant has shown that, due to extraordinary circumstances, s/he cannot wait for the normal licensing process to conclude. See also Construction Notification.

Specific Area Message Encoding (SAME)

Discontinued in 2022, digital codes keyed to each county, programmed into a NOAA weather radio receiver so EAS 'all hazard' alerts will broadcast over specialized weather receivers and Travelers Information Stations.

SPDT

See Single Pole Double Throw.

SPST

See Single Pole Single Throw.

SS.3000 Free-Standing AM Radio Antenna System with Tower (SS.3000)

See Free-Standing AM Rado Antenna System with Tower SS.3000.

STA

See Special Temporary Authority.

Standard Antenna

See ANXX AM Radio Antenna.

Standardized Equipment List (SEL)

Also known as InterAgency Board (IAB) Interactive Standardized Equipment List

Guideline used voluntarily, intended to promote interoperability and standardization across the emergency response community at local, state and federal levels by offering standard references and common terminology. The Interagency Board provides subject matter expertise on equipment used by first responders and other emergency management professionals and maintains the Standardized Equipment List (SEL) which has most of the equipment types listed on the Authorized Equipment List. The numbering scheme for individual items on the Authorized Equipment List provides direct cross-referencing with the Standardized Equipment List. The Standardized Equipment List has relevant standards, training requirements and operating considerations for many of the equipment items. See also Authorized Equipment List.

Standing Wave Ratio (SWR)

Standing-wave ratio (SWR) is a mathematical expression of the non-uniformity of an electromagnetic field on a transmission line, such as coaxial cable and/or a connected antenna system. Antennas are adjusted to make the SWR as low as possible (1:1) in order to make the antenna efficiency as high as possible. Typically, a SWR as high as 2:1 is suitable for Travelers Information Station operations. A 2:1 SWR correlates to a 10:1 ratio of forward to reflected transmitter power.

Stealth Sign

Fixed-message LED signs that are dark when not activated. See Stealth Sign webpage.

Storm Sensor

See SSD.20 Severe Storm Detector.

StreamCAST Internet Broadcast Service

See HearMoreInfo.

Streaming Broadcasts to the Internet

See HearMoreInfo.

SuperStation 3000 Antenna System

See Free-Standing AM Rado Antenna System with Tower SS.3000.

SWR

See Standing Wave Ratio.

SX.200 Wattmeter

See Wattmeter (SX.200).

Talking House AM Radio Transmitter (TH.5) with or without i A.M. Radio Enhanced Audio

Updated and absorbed into the newer InfOspot AM Radio Transmitter System in 2020.

thematchbox

Introduced by Information Station Specialists in 2023, a broadband multi-tap transmission-line transformer that raises the magnitude of the characteristically low impedances of electrically short end fed antennas to an impedance suitable for direct connection to 50-ohm coaxial cable without significant loss or standing wave ratio. Superior to conventional transformers which perform well only above 1 MHz, THEMATCHBOX works well at low frequencies (down to 100 kHz) due to its manganese zinc alloy composition. See a technical specs.

Tip and Ring (T/R)

Names of the 2 conductors or the side of a telephone line.

TIS

See Travelers' Information Stations.

TIS Rules

See Part 90 FCC Rules.

TMS.020 Digital Audio Management System

IP-based digitial audio management system. See webpage. See also an audio control methods comparision chart.

tornadoAlert

See SSD.20 Severe Storm Detector.

Touchtone

See Dual-Tone Multi-Frequency Signaling (DTMF).

TR.6000 AM Radio Transmitter Model 15.73 (FCC Parts 15 & 73/1560)

A 10-watt AM transmitter supplied only by Information Station Specialists for unlicensed broadcast operations (Part 15) and emergency / reduced power broadcast service (Part 73/1560). See details on this webpage.

TR.6000 AM Radio Transmitter Model HQ 5.0 (FCC Part 90)

A 10-watt AM transmitter supplied only by Information Station Specialists for all licensed Travelers Information Stations the company provides. The TR.6000 HQ 5.0 is type accepted according FCC standards for the TIS service. See details on this webpage. See also HQ 5.0 Audio Filter and HQ 5.2 Audio Processor.

Travelers' Information Station (TIS)

Also referred to generally as Information Radio Stations, and in specific applications and station setups, as Emergency Advisory Radio, Highway Advisory Radio or Low Power Radio.

Legal term used by the Federal Communications Commission to define a 10-watt radio station that operates on AM-band frequencies 530-1700 kHz; signal coverage is 2.0 mV/m at 1.5 km, which typically yields a signal radius of 3-5 miles. The Federal Communications Commission licenses the stations to state and local government agencies, such as regional emergency managers, under Part 90.242 Rules, issued in 1977 and updated and clarified in the 2014 FCC TIS Compliance Guide. Federal agencies, such as National Parks and the Department of Homeland Security, obtain authorization for their TIS stations to operate separately through the National Telecommunication and Information Administration. TIS broadcasts are intended for motorists and must be commercial-free, voice-only public-safety/service-oriented. Emergency managers may broadcast any information to preserve life and property when danger is imminent. Motorists are notified to tune to the stations via road signs, which typically incorporate flashing beacons.

ISS trade names include ALERT AM, RadioSTAT, VoiceStar and the Information Station (click each preceding trade name for individual descriptions).

Two-Tone Sequential

Also known as 1+1

"Two-tone sequential" is a dual-tone selective calling method used in one-way paging transmissions.

UHF

See Ultra High Frequency.

Ultra High Frequency (UHF)

The designation for radio frequencies in the range of 300 MHz and 3Ghz. UHF radio waves propagate mainly by line of sight.

Unirod

See Groundrod.

VAC

See Volts of Alternating Current.

VDC

See Volts of Direct Current.

Vertical Profile Antenna Support and Grounding System

See VP.9000 Vertical Profile Antenna Support and Grounding System.

Very High Frequency (VHF)

The International Telecommunication Union (ITU)-designated range of radio frequency electromagnetic waves from 30 MHz to 300 MHz, with corresponding wavelengths of 1 to 10n meters. (ITU coordinates the shared global use of the radio spectrum.) Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).

VHF

See Very High Frequency.

VoiceStar Portable Information Radio Station and Changeable Message Sign on Towable Trailer

Solar-powered, wireless controlled, trailer-mounted, portable Travelers Information Station (TIS and HAR) with optional changeable message sign. Throws a full 25-to-75 square-mile signal (3 to 5 mile radius) to motorists. Often used in association with highway construction for incidents and emergencies. See VoiceStar webpage. Information Station Specialists offers VoiceStar in partnership with the American Signal Corporation.

Volts of Alternating Current (VAC)

The measured electrical potential (voltage) of an Alternating Current circuit.

Volts of Direct Current (VDC)

The measured electrical potential (voltage) of a Direct Current.

Volume Units (VU)

Base units of length and volume linked in the metric system. By definition, a liter is equal to the volume of a cube exactly 10 cm tall, 10 cm long, and 10 cm wide. Because the volume of this cube is 1000 cubic centimeters and a liter contains 1000 milliliters, 1 milliliter is equivalent to 1 cubic centimeter.

VP.9000 Vertical Profile Antenna Support and Grounding System

A previously patented aluminum antenna support pole and antenna grounding system, in one. The antenna lightning arrestor and cables are housed inside the pole, accessible through a service hatch to discourage vandalism. VP.9000 requires less ground disturbance and installation space and is an unobtrusive antenna-grounding solution for Travelers Information Stations (TIS and HAR). See also a TechTalk article entitled, Why Antenna Grounding Is Important, How It Works and Is Installed.

VU

See Volume Units.

W or w

See Watt.

WAL

See Wireless Audio Link System.

Watt (W or w)

Standard unit of measure of power equipvalent to one joule per second and equal to the power in a circuit in which a current of one ampere flows across a potential difference of one volt.

Wattmeter (SX.200)

A valuable tool for installing and maintaining Travelers Information Stations. The wattmeter is used to tune the station's antenna and to determine if the antenna and transmitter are working efficienty (by allowing the measurement of the antenna system's forward and reflected power). Trade name: SX.200. See TechTalk article: Troubleshooting with a Wattmeter.

Wireless Audio LinkSystem (WAL)

A method of linking a continuous audio program from a central source to multiple Travelers Information Stations by RF means.


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