Frequency (bands) — frequency waves are divided into bands with conventional names. Common frequency bands in SLS are; very high frequency (VHF, 30 – 300 MHz) and ultra-high frequency (UHF, 300 – 3000 MHz). SLS uses different frequency bands depending on coverage requirements. Each SLS state radio network may use a single or combination of frequency bands.
The use of some frequency bands is for commercial use only and requires a licence from the Australian Communications and Media Authority (ACMA). Using unlicensed or incorrect frequencies may result in penalties.
Analogue radio — analogue radio transmits radio waves in amplitude modulation (‘AM’) or frequency modulation (‘FM’) by a signal. Older SLS radio networks and VHF marine radio use analogue radio technology.
Digital radio — digital radio provides greater voice clarity and eliminates unwanted background noise. Most SLS and government radio networks use digital radio technologies. Digital radio networks also support other functionality like GPS tracking.
Channel — a channel is a frequency (either simplex or duplex) programmed into a radio that is used by SLS or other agencies to communicate with each other. Each SLS branch or state centre may have different channel configurations.
Simplex channel — a simplex channel sends information in one direction at a time, and may be reversible. The transmitter and receiver are operating on a single (or the same) frequency. You cannot transmit and receive radio transmissions simultaneously on a simplex channel. Simplex channels are limited to line-of-sight communications.
Simplex communicationDuplex channel — a duplex channel uses a pair of frequencies consisting of one to receive and another to transmit. Duplex channels are used mainly as repeater channels and cannot be used for simplex or direct communications.
Repeaters — repeaters receive transmissions on one frequency and transmit on another (or second frequency). They are fixed transceivers that receive line-of-sight signals and transmit them to broaden the radio coverage. Generally speaking, the higher up a repeater is located (e.g., on a hill), the further a message can be re-transmitted.
Duplex communicationNetwork — a radio network is a number of fixed and mobile repeaters linked together to cover a larger area. A network may service a SLS branch, geographic region or even an entire state.
Station — a station relates to the call sign of a particular radio user, group of users or SLS entity.
Check your SLS state centre SOPs regarding the specific radios, radio network and channels used at your surf lifesaving club or service.