SA police get in-vehicle repeaters

The South Australian Government Radio Network (SAGRN) is one of the largest wide area radio networks in the world, covering several thousand square kilometres from the WA border to the Victorian border in the east. Established in 2000, the network is being upgraded from analog technology to a state-of-the-art P25-based system.

Following a competitive tender process, Tetracom has been contracted by SA police to improve the functionality of many of their vehicle-mounted radios in their fleet by adding in-vehicle repeater (IVR) modules manufactured by LMR Systems. The advantage of the IVR is that it will provide extended coverage from portable radios in remote areas as well as improved in-building coverage in built-up areas. The equipment is fully compatible with the current system and will easily upgrade to the new P25 system as the transition occurs.

The IVRs work by leveraging the higher performance of the in-vehicle radios with their more efficient antenna systems and higher output power, which in turn interfaces via the IVRs to a second, local antenna system. When the officers leave the vehicles the IVRs are activated, which then enables their portable radios to connect to the main wide area network. This often occurs in areas where the portable radios may not have reliable coverage on their own.

The IVR enhances the communication capability of the portable radios, allowing for greater flexibility and convenience to the officers while providing more control and feedback in any incident - thereby enhancing the safety of the general public and the officers themselves.

The IVR ensures all communication remains securely encrypted end-to-end, eliminating the possibility of external interference. Should multiple vehicles attend an incident, the IVRs have a built-in priority algorithm ensuring that only one repeater is active on any given talkgroup. This algorithm covers vehicles entering and leaving a scene, with each IVR constantly communicating with other nearby units.

A priority hierarchy is established to ensure that only one IVR is in repeat mode at any given time in order to prevent collisions in transmit activity. This ensures that each officer is using the same channel and all who are in attendance are able to be involved in all critical communications at all times.