Terminology 700 MHz: A radio, system or channel that operates within the range of the 794-815 MHz. These systems may be conventional or trunked. 800 MHz: A radio, system or channel that operates within the range of the 839-860 MHz. These systems may be conventional or trunked. A Amplification: The process of increasing the strength of a radio signal. APCO: Association of Public Safety Communications Officials, www.apco911.org B Backward compatibility: Ability of new units to operate within an "old" system infrastructure or to directly intercommunicate with an "old" unit. Band Plan: A plan to allocate different frequencies within a range for specific purposes and users. C Cache radios: A spare set of radios maintained as a shared regional resource; the radios are fully charged, include extra batteries and chargers, and are labeled with the owner agency name, frequencies, band and system. These radios are typically programmed with a set of interoperability channels or talkgroups. Call Sign: A group of letters and numbers used to identify a station and the country authorizing its operation. The Federal Communications Commission (FCC) assigns Call Signs to each station. Calling Frequency: An agreed-upon frequency where stations attempt to contact each other; once contact is made, stations move to a working frequency. Also known as a "hailing frequency". Car to car: To communicate with another station without using a repeater. To transmit and receive on the same frequency. Also referred to as direct or simplex. Carrier: The un modulated output of a radio transmitter.
CB: Citizens Band radio Channel Integrator: A sophisticated, process/device or system which takes several inbound radio signals from a variety of bands and electronically interconnects them on the outbound side to one or more other otherwise incompatible radio channels. Examples: JPS ACU-1000 switch and Ma/Com s Network First switch Channel: The frequency on which a radio transmission takes place, or the input and output frequency pair used by a repeater station. May also refer to the assigned number on the radio selector knob of the mobile or portable radio. Co-channel Interference: Interference from stations on frequencies adjacent to the desired signal. Console Patch: Buttons or icons in the dispatcher s radio console that (when properly selected) permit the ability to patch or connect two dissimilar regular radio channels or trunked radio talkgroup together for a specific conversation. (Example: Patching the VHF Fire Channel to the UHF Street Department Channel) Control Point: The physical location from which a radio station s functions (setting frequency, turning the station off and on, etc.) are controlled. COTS: Software and hardware products that are ready-made and available for sale to the general public. COTS products are typically installed in existing systems and do not require customization. Cross Band Repeater: A single device which receives inbound radio traffic on one channel in one band (say MINSEF on VHF @ 155.475 MHz) and rebroadcasts it out on another channel in another band (say NPSPAC InterOp Channel 1 at 866.0125 MHz) and vice-versa D Dead Zone: A region where a radio signal cannot be received due to propagation difficulties. Digital & Analog: The methods of modulating a radio signal as it travels through the air. Example: Digital signals are the speaker s words turned into a series of 1 s and 0 s, which are then transmitted through the air, received at the other end and then reconstituted back into the audio sounds of the speaker s words. The translation process is done by a device called a "vocoder". Analog signals are the speaker s words translated into wave forms and the wave forms are then sent through the air and can be heard through a loudspeaker at the receiving end.
Generally, analog wave forms require a wider radio channel bandwidth than a digital transmission carrying the same sound, but digitally. Direct: To communicate with another station without using a repeater. To transmit and receive on the same frequency. Also referred to as simplex; or car to car. DTRS: Digital Trunked Radio System. Colorado operates a statewide DTRS radio network providing service to federal, state, and local agencies. The system operates in the 700/800 MHz band. Duplex: To transmit on one frequency while listening for replies on another. E EDACS: Enhanced Digital Access Communications System. The 10 county metropolitan area around the City and County of Denver operate using several interconnected EDACS radio networks. This system operates in the 800 MHz band. Encryption: In digital radio systems, all radio transmissions are digitized (broken down into a formatted series of 1 os and 0 s according to some logic mutually known to all radios on that system) at a minimal, standards based level. In an encrypted system, these digital bits are re-coded one again based on a secret code known only to the radios within the system that have been programmed with that same secret code. In older analog radio systems, if encryption was employed, analog voice sounds were digitized, and then sent over the analog channel as an analog wave form to the distant radio, which had to have the similar decryption program in it to unscramble what the transmitting radio sent. This technique dramatically reduced the effective range of the otherwise analog signal, whereas with modern encryption employed over already digital systems, there is no degradation in signal quality or range. F FCC: Federal Communications Commission Fixed gateways: A device which is used to connect channels and/or talkgroups from disparate radio systems together. A fixed gateway is one permanently installed within the radio system infrastructure. The NetworkFirst Gateway serving the Denver metro area is an example of a Fixed Gateway.
Frequency: A defined unit of electromagnetic spectrum expressed as the exact location of the assigned channel in the spectrum. For example, the Fire Emergency Radio Network (FERN) operates on Frequency 154.2800 MHz. FRS: Family Radio Service; radio frequencies that do not need an individual license. FRS radios have shared frequencies and short range. G Gateways: : A device which is used to connect channels and/or talkgroups from disparate radio systems together. Gateways may either be "fixed" (permanently installed within the radio system infrastructure) or "mobile" (which can be brought to an incident scene). Dispatch Center radio consoles can also "patch" channels and talkgroups together and are sometimes also referred to as console gateways. Gain: The apparent increase in the strength of a signal radiated or received by an antenna caused by the antenna having better performance in some directions than others. Gigahertz: Unit equal to 1000 megahertz or 1,000,000 kilohertz GPS: Global Positioning System Ground: A connection to a point of zero voltage, like the Earth. H Hard Patch: A system whereby a dedicated radio is installed to take what it hears and always patch it over to another radio system channel or talk group, and (sometimes) vice-versa. (Example: The Street Department s UHF radio channel is hard patched to a talk group in the police department s trunked radio system which could be called streets ). Hertz: One complete cycle of a radio wave per second. High VHF: 150-174 MHz I IP: Internet Protocol Input Frequency: The frequency on which a repeater station listens for signals to retransmit.
Intermod: Short for "intermodulation," this means false or spurious signals produced by two or more signals mixing in a receiver or repeater station. ISSI: Inter-RF Subsystem Interface K Kilohertz: Unit equal to 1000 hertz. Kilowatt: Unit equal to 1000 watts of transmitter power. L LMR: Land Mobile Radio Low Band: A system or channel that operates in the 39-45 MHz band. Low UHF: 450-470 MHz Low VHF: 30-50 MHz M Megahertz: Unit equal to 1,000,000 hertz or 1000 kilohertz. Microwave: A point to point radio system that transmits signals (often data) from one fixed point (microwave dish) direct, in a line of sight mode, to another fixed point. Often microwave is implemented to bypass expensive, monthly recurring costs for data lines leased from the phone company. Mobile Gateways: portable interconnect switches that connect two or more disparate radio systems. Mobile Station: A two-way radio unit installed in a car, boat, plane, etc., and used while in motion or at various stops. Multiband Antenna: An antenna suitable for operation on several different bands of frequencies N Narrowbanding: Starting in 2013, all radio systems operating below 512 MHz must be narrow band compliant. Splits a 25 KHz wide channel into two separate 12.5 khz wide channels. When technology permits, another migration will occur
down to 6.25 Khz channels. Most agencies in Colorado have already completed the first migration to 12.5 Khz. NPSPAC: A radio, system or channel that operates in the 800-815 & 845-860 MHz bands. NPSPAC stands for "National Public Safety Planning Advisory Committee". NPSPAC channels operate under more stringent FCC rules regarding power output by base stations, so as to permit more channel re-use across a geographic area such as a state. NPSTC: National Public Safety Telecommunication Council O OEC: Office of Emergency Communications, a division of the Department of Homeland Security. Omnidirectional Antenna: An antenna that transmits and receives equally well in all directions. Output Frequency: The frequency on which the base station radio or repeater transmits the voice or data signal to another radio user or device. P P25: APCO Project-25 Digital Standard, also referred to as Common Air Interface (CAI). APCO Project 25, or "P-25" for short, is the public safety industry standard developed by the APCO International (Association of Public Safety Communications Officials) to provide a radio solution that would allow different agencies using different radio systems to interoperate according to a public safety industry standard and not by system manufacturer. Patch: The ability of a dispatch console to connect or merge two or more channels or talkgroups together to allow inter-communication between units on those different channels and talkgroups. This is sometimes referred to as a console gateway. Priority Channel: The channel or talkgroup selected in a mobile or portable radio which will cause the radio to revert to that channel or talkgroup when a transmission is received, even when the radio is scanning and has stopped on another voice channel or talkgroup. Propagation: The process of how a radio signal travels. Radio waves may bounce or be deflected by bodies of water, buildings, glass windows and terrain. PTT: Abbreviation for "Push-to-Talk," the switch on a subscriber unit which, when pressed, causes the subscriber unit to transmit.
R Radio Extender/Vehicular Repeater: A device which allows a portable handheld radio to communicate to a vehicle based mobile radio, which will then retransmit the voice message into the main radio system. These systems are used in locations where the portable radio is not able to communicate directly to the main radio system and needs to talk through the mobile radio which can transmit a stronger signal. These systems have many names, including Pac R/T, Pack Rat or Vehicular Repeater. Re-Banding: An FCC mandated process (begun in about 2005 and lasting several years in several waves ) under which numerous public safety licensees operating radio systems in the 821 and 866 MHz band were relocated to a lower set of frequencies to avoid harmful interference caused by Nextel radio systems. Repeater: A base station transmitter/receiver which receives inbound radio traffic on one channel and simultaneously re-broadcasting it out of the base station antenna with increased power and range. Example: A VHF repeated channel may have field radios talking in on frequency 156.0150 MHZ and the base repeater re-broadcasting the signal back out on frequency 155.7900 MHz. S Satellite (or voting) Receiver System: A set of two or more receive only devices placed out in the field at various locations to pick up weaker inbound radio signals and bring them into the main base station or dispatch center via phone lines, microwave or other service. Another device instantly checks the quality of the signal coming from each of the listening posts and selects the best quality signal which is then sent to the dispatcher's console and repeated back to the field units. SDR: Software Defined Radio. A radio capable of reconfiguring itself to transmit on different radio spectrum bands and capable of interconnecting with multiple types of radio systems. Shared Channels: Common channels or trunking talkgroups that have been established and are programmed into radios to provide interoperable communications among agencies. Shared Systems: The use of a single radio system infrastructure to provide service to several Public Safety agencies within a region. Simplex: To transmit and receive on the same frequency. Also referred to as direct; or car to car.
Simulcast: The process of having a radio signal transmitted simultaneously from multiple transmitters in different locations so as to increase the area over which that radio signal can be heard, as well as the chances of that radio signal effectively penetrating dense buildings. Skip: Any type of sky wave propagation via ionospheric refraction. Squelch Tail: A brief bit of noise heard between the end of a radio transmission and the reactivation of the receiver s squelch circuit. Squelch: A circuit in a radio receiver that quiets the receiver until the strength of a received signal exceeds a specified level T Talkgroup: A virtual talk path used in a trunked radio system to denote a particular radio resource assignment. The phrase virtual channels is used in that they only really exist in the radio system when they need to be used, and the rest of the time they only exist on paper, or in a series of instructions programmed into the trunked radios and system. Telemetry: One-way radio transmissions used for tracking and measurement data. In some systems, paramedics use Telemetry systems to transmit a patients heart rhythm to the hospital emergency room. In other systems, telemetry signals will monitor the water level at a local utility plant and transmit an alarm if the level is too high. Time-Out: A programmable setting in both base station, portable and mobile radios which will stop the radio from transmitting for a long period of time. Many radios will emit a tone to alert the user that they transmitter has been turned off and they will need to "rekey" the radio to continue talking. These systems are designed to prevent continuous interference from a radio that has malfunctioned with its microphone open. Trunked Radio System: A computer managed radio system with multiple radio channels. For each transmission, the computer assigns a channel to the participants for the duration of that transaction. U UHF High: The frequency range from 760 to 860 MHz. 760-806 MHz radios are often called 700 MHz radios, 806 to 860 MHz radios are often called 800 MHz radios. Radios that cover the entire spectrum are often called dual band radios. UHF Low: The frequency range from 450 to 470 MHz.
UHF: A system or channel in the Ultra High Frequency range around 450-460 MHz V Very High Frequencies: The frequency range from 30 to 300 MHz. VHF High Band: The frequency range from 150 to 175 MHz. Most Public Safety radios operate in the 150-160 MHz range. VHF Low Band: The frequency range from 30 to 50 MHz. VHF: A radio, radio system or channel that operates in the Very High Frequency band around 150 Megahertz (MHz). If your FCC license says something like 155.250 MHz that s a VHF channel. Vocoder (Abbreviation for voice-coder): A device that usually consists of a speech analyzer, which converts analog speech waveforms into narrowband digital signals, and a speech synthesizer, which converts the digital signals into artificial speech sounds. VoIP: Voice Over Internet Protocol W WB: Wide Band Wi-Fi: Wireless Fidelity WiMAX: Worldwide Interoperability for Microwave Access WLAN: Wireless Local Area Network Y Yagi: A directional antenna consisting of a dipole connected to the receiver or transmitter and two additional elements, a slightly longer reflector and a slightly shorter director. Electromagnetic coupling between the elements focuses maximum power (or reception) in the direction of the director.
More Information: A. Association of Public Safety Communications Officials, Inc. (APCO) www.apcointl.org B. Federal Communications Commission Public Safety and Homeland Security Bureau www.fcc.gov/pshs C. Federal Communications Commission Universal Licensing System (FCC ULS) wireless.fcc.gov/uls D. Homeland Security Information Network (HSIN) government.hsin.gov E. Lessons Learned Information Sharing (LLIS) www.llis.gov F. National Emergency Number Association (NENA) www.nena9-1-1.org G. National Interagency Fire Center (NIFC) www.nifc.gov H. National Interagency Incident Communications Division (NIICD) www.nifc.gov/niicd/index.htm I. National Interoperability Information exchange (NIIX) www.niix.org J. National Public Safety Telecommunications Council (NPSTC) www.npstc.org K. National Wildfire Coordinating Group (NWCG) www.nwcg.gov L. Safecom www.safecomprogram.gov M. Radio Reference www.radioreference.com N. National Telecommunications Industry Association (NTIA) www.ntia.gov