Page Title

Voice Alarm

Nextronic Ltd is a specialist design and manufacturing company, who can provide systems to fulfil the need for Voice Alarm, Public Address and Background music, in almost any building or site, in the public, commercial or industrial sectors. Our objective is to provide simple and cost effective solutions, which are easy to specify, install and maintain.

Emergency warning signals to the occupants of a building or site have traditionally been given by audible alarm such as bells and sounders. This can be effective when all the occupants have been trained for such procedures. However, where the general public may be involved, such training is impossible, and an emergency situation can cause confusion and panic.

It is now widely understood that the use of a recorded voice message (termed ''Voice Evacuation'', or "Voice Alarm" or VA), when broadcast over loudspeakers, will effectively evacuate the building, or indeed reassure the occupants of the precise nature of the incident.

The System

A Voice Alarm system is typically installed to fully replace the fire alarm sounders or bells. It is important therefore that the system achieves at least the same reliability and performance of the fire system. Nextronic wholly recognizes this, and as such the Voice Alarm system is treated as life safety equipment.

From 12 years experience in the industry, Nextronic has focused on the design and manufacture of Public Address and Voice Alarm systems. We can offer an enhanced, and simplified system solution, to fully comply with the requirements of BS 5839 pt 1 and pt 8, EN BS 60849, BS 6259, and the former BS 7443.

The system gives facilities for: Voice Alarm - Public Address - Background Music

Voice Alarm may be global, or phased with any number of simultaneous active voice alarm zones.
Fire microphones have the highest priority, and may have global or zoned access.
Public Address facilities include paging zone or zone group selection, user chime selection, signal processing (volume level, graphic equalization and compression), all programmable on a per zone basis.
Any numbers of simultaneous audio broadcasts are possible, from the operator microphones, message playback or background music sources.
Any number of priority-configured microphones or background music sources is also possible.
The system has facility for interfacing with any fire detection system, an existing audio system, and local alarm sounders.

Due to the modular nature and programmability of the system, configurations of any combination of the above can be offered, from simple paging zones, to full phased evacuation.

The Design - DNS 'Digital Nodal System'

Using the latest micro controller technology, combined with established audio and system monitoring designs, this makes the Nextronic DNS units an extremely flexible and reliable control system. The integrated design means that the DNS node can be very compact, yet does not compromise in any way on the system facilities.

Beneath the flexible control system, lies well established circuits for basic system audio and monitoring functions, which are well proven and reliable in operation. Reliability is further enhanced since each DNS node is itself a Voice Alarm system, capable of fully independent operation. Unlike most centralized systems, this means that the possibility of 'single point failures' in the DNS system, are eliminated.

The system is very power efficient, which means that power supplies and battery backup can be minimized. This is achieved by using class 'd' amplifiers, and low power system control circuits. The 24hr battery back-up design, takes full account of the de-rating factors recommended by BS 5839 pt8.

Suitable for centralized or decentralized formats, the DNS nodal system may be expanded in zone and power capacity, virtually without limit (over 100 zones, each of 200W capacity). Expansion of the system is simply by adding extra DNS nodes, either into spare cabinet space, or located remotely in the area where the loudspeaker zone has been extended.

In a distributed system arrangement, DNS nodes use serial data, on an industry standard RS485 network. This significantly reduces the cost of installation, commissioning and maintenance, as well as increasing reliability. The heavier cables associated with loudspeaker distribution can be minimized, and a lightweight multi-core cable provides a common loop for audio and control between each DNS node.

The main objectives of the design are as follows:

Simple to specify and design.
Simple to re-configure and expand in the future
Flexible to interface with other systems (eg. Local Fire Panels, Building Control systems, existing audio systems, etc.)
Easy to understand and operate.
Easy and cost effective to install (typically 3 pair screen to each node)
Simple to maintain

Applications

As a single zone Voice Alarm, a wall-mounted unit can be used in stand-alone operation. For larger systems the DNS units are grouped together and mounted in a standard 19'' cabinet. The system will interface directly with any fire detection system. The local loudspeaker system can be either at 100V line, or low impedance (4 or 8 ohm).

Applications are many and varied, but are typically in situations where there may be persons unfamiliar with fire evacuation practices, in the building. Configurations of units are suitable for anything from; single zone retail units, to multi-storey offices, to sports arena.

Technical Summary - DNS-DVA Module

The key system element is the DNS unit (Digital Nodal System). The DNS nodes are networked together, either in a single rack (for centralised systems), or in remotely located racks (for distributed systems). One or more DNS unit is used for each broadcast zone of the system. Microphones, and other audio and control sources connect directly to the DNS node.

The system can offer the following major technical system advances, and facilities:

High reliability operational configuration: each DNS-PA node comprises a complete and independent PA amplifier and control system. Failure of any node would not affect operation of any other part of the system.
Truly standardised hardware design: Fully configurable in firmware without need for ''custom'' designed hardware elements.
Highly efficient low power operation: Class 'd' power amplification and low power control and monitoring system, means very low UPS or battery backup requirements.
Simple configuration of system elements: Access/ Control/ Amplifier nodes may be star or loop or branch configured within the network
Comprehensive system fault supervision: LED healthy status and, LCD text status display of fault detail (available at every node).
Engineering Maintenance panel for each DNS-DVA Node:
Test microphone
Alarm function test
Audible Zone test (tick tone)
Line sensing setup
Status indication: busy, healthy, signal peak/ present
BGM volume setup
Fault buzzer, Accept and Reset fault log.
High Integrity Amplification:
Dual circuit amplifiers per Zone,
Fully protected with auto attenuate on overload,
Auto recovery on clearance of fault.
Monitored hot-standby amplifier with auto changeover on main shutdown.
Flexible, programmable system configuration:
Secure serial data control: Dual circuit serial data paths are used to ensure that a single fault on a data cable cannot cause a common system failure.
Non-volatile Digital Audio Storage is available at each node, for high integrity Voice Alarm and voice message broadcasts. Standard or custom recordings may be specified.
Pre announcement chimes and general message broadcasts are stored and accessed from any microphone input station.

Interfacing to external systems eg Building Management System, or to a PC and modem for remote logging of system fault status, and operation status.