Mesh technology is ideal for disaster management agencies as they “bring their own network” to locations where communications infrastructure typically is unavailable. This could be to the site of an earthquake, or an underground train collision, or a road tunnel accident, or a terrorism incident where the authorities have shut down the cellular network.

In this instance, the exercise was to simulate a disaster in a train tunnel, half-way between two train stations, at a distance of 300 metres along the train tunnel, with the platform located 25 metres below ground. The five different levels involved many right-angle turns to descend stairs. This site is a regular training location for underground rescue and the agency’s DMR radios cease to function before the user reaches the train platform at the fifth level.

The challenge was to deliver audio and data (tracking PLI data) to the Command Post on the surface, outside the entrance to the station. In addition, they wanted to backhaul the network to their HQ via unified communications system. When we asked if they would like to also stream live video from the incident, they just laughed at the idea, believing it impossible in their experience.

There were six domestic agencies in attendance and two agencies from neighbouring countries, a mixture of Search & Rescue, Counter Terrorism, Civil Defence, Military and Law Enforcement, as well as the operator of the train network.

We established a Command Post inside a temporary tent structure with our Unified Communications vehicle close by. Two GUIs were set up, one to display the Mesh network status, video stream, and GPS (for the Mesh radios on the surface) and a second to display the real-time live tracking data (over three axes X/Y/Z). This utilised four of our Mesh radios. A further three of our small, hand-held, battery operated PTT Mesh radios were dropped on the way down the stairs as we witnessed low SNRs on our network status app running on our mobile devices. The RF output power of these radios is a single 500mW transmitter, with dual diversity receiver, and zero DB gain antennae.

All of our body-worn/hand-held Mesh radios have integral Wi-Fi access allowing ease of connectivity for apps running on user’s mobile devices. The ease of determining network status on the move, and the easy placement of radios as relays “on the move” was perceived a major benefit to operations.