The renewal specification was prepared on the basis of using VoIP (Voice over Internet Protocol)
DLR wanted to renew the existing public address system along with making provisions for high-speed LAN

All metro railways need to be able to inform the travelling public on how the trains are running. Routine next train information is normally by platform indicators but out-of-course events need audible announcements. DLR has long had a long line public address capability but the system was showing signs of age as well as having few diagnostics. Renewal across the network was urgently needed. The opportunity to combine the renewal with the provision of the high speed LAN was there for the taking so the specification was prepared on the basis of using VoIP (Voice over Internet Protocol). The configuration includes -

    • ASL's iPAM intelligent PA amplifier of up to 400W at each station
    • a loudspeaker chain monitoring capability to be phased in when the loudspeakers are eventually renewed
    • a PC-based digital voice announcer for text-to-speech messages
    • voice alarm provision at selected stations for evacuation purposes
    • a mini iVENCS Graphic User Interface (GUI) at the control room giving geographic representation of the railway with easy-to-select, colour-coded zones and announcement status
    • microphones at the control room and at selected key stations
    • a ‘listen in’ facility for the controller to hear the live broadcast at stations
    • full Ethernet connectivity to maximise the diverse routing potential of the LAN

telent again successfully won the contract for the system design thus facilitating easy integration with the LAN. The main LLPA equipment supplier is UK based ASL safety & Security. To reduce cost, the existing loudspeakers have been used as these were in good overall condition. The system is now installed and working well. Its monitoring capability is showing a big improvement in performance over what went before. A significant new feature is the ability to update standard recorded messages for each station from the control centre, rather than have to visit each site to update the firmware. An interface unit is provided to link the system to the OTN and the existing LLPA equipment on the Lewisham extension.