Glossary

Following are some common terms used in two-way radio and trunking.

Antenna- The device (normally similar to a wire) used to convert the electromagnetic energy in the air to an electrical signal that a receiver can process. The dimensions of an antenna are mathematically related to the frequency it will work best for. Normally, higher frequencies will use smaller antennas.

Base Station- A fixed, or stationary, transmitter-receiver.

Channel- the frequency or talkgroup a radio is operating on.

Comparator- An electronic device to automatically the best of two or more signals. Also called a voter.

Control Channel- One frequency in a trunking system that is used to convey system information such as frequency assigned for a talkgroup call and what talkgroup a radio has selected.

Controller- A computer that is used to control a simulcast or trunking system, or a remote simulcast site.

Dispatch- The act of sending instructions to field personnel in day to day operations. Also an abbreviation for Dispatch Center, the place where Dispatchers work.

Duplex- A method of transmitting and receiving via two different “channels” or paths. Full duplex means transmit and receive can occur simultaneously and half duplex means one function needs to wait for the other to be completed.

Failsoft- A trunking system failure mode. Under certain conditions, the trunking system may not be able to continue trunking. Each frequency then operates as a repeater with two or more talkgroups sharing the frequency.

FCC- Federal Communications Commission

Field Unit- A mobile or portable radio. Also called subscriber unit.

Key- To cause a radio to transmit

Mobile- A two-way radio that is designed for installation in a vehicle.

Modulation- The method of putting intelligence on a radio signal.

OmniLink- A wide area trunked radio system consisting of two or more Smart Zone systems.

Portable- A two-way radio that is designed to be carried by a person.

Prime Site- The grouping of electronics that controls a simulcast system. The Zone Controller and it’s associated equipment can also be called a Prime Site.

PTT- Press To Talk button on a portable or microphone used to cause the transmitter to transmit.

Remote Site- One of two or more simulcast transmitter sites.

Repeater- A radio receiver/transmitter that receives on one frequency and rebroadcasts the signal on a different frequency. Repeaters normally operate in full duplex mode.

RF- Radio Frequency- The 800 MHz signal

Satellite Receiver- One of two or more receivers connected to a voting comparator.

Signal- The radio frequency information received by a receiver that carries voice information.

Simplex- Transmitting and receiving on the same frequency.

Simulcast- Transmitting the same signal from two or more sites simultaneously.

Site- Normally refers to the location of transmitting and receiving equipment. For a Smart Zone system, site also refers to an entire simulcast subsystem.

Site Trunking- This is when a Smart Zone site is “disconnected” from the Zone Controller. The site will continue to process traffic and trunk, but it is acting in a stand-alone manner and cannot share traffic with other Smart Zone sites.

Smartnet- The “brand name” given to a Motorola trunking system. A Smartnet system can be either single-site or simulcast.

Smart Zone- The Motorola “brand name” for a wide-area trunking system made by tying two or more Smartnet systems together. The individual Smartnet systems can be any mix of single-site and simulcast.

Subscriber (Unit)- A mobile or portable radio used by personnel not at fixed locations.

Talkgroup- A specific set of radio users with a common ID that are allowed to talk to each other and are assigned a particular frequency.

Trunk (ed) (ing)- A method of grouping of frequencies so several users can use the grouped resources, thus increasing capacity to carry conversations.

Voter- Another name for “comparator” or “voting comparator.” A device that selects the best receive signal from two or more receivers.

Zone Controller- The central computer used to control a Smart Zone trunking system.