BDA's can be deployed to extend existing systems and provide coverage inside tunnels. Examples are DMR Tier 2/3 or TETRA systems where the local sites provide coverage outside the tunnel, but this does not extend beyond the entrance of the tunnel. A BDA could sample the signals at the entrance to the tunnel and then repeat them down its length either via leaky feeder, or via a series of remote units connected by optical fibre. BDAs offer a rugged design and IP65 Sealing to suit the harsh environments tunnels can have.
DMR E-Pack or E-pole could be used to repeat a single frequency within the tunnel via a wireless mesh. This reduces the need for any cabling within the tunnel as they automatically set up an ad-hoc network via wireless mesh – allowing communication between any personnel in the tunnel and on the train itself. The E-Pack/E-pole work in single frequency repeat mode and communicate with standard DMR Tier 2 radios such as the H Series. This is very spectrum efficient as only one frequency is required. Both the E-Pack and E-Pole offer a rugged design, the E-pack is IP67 and the E-pole IP56.
