Alarming developments

Chris Fitzsimmons examines some of the technical and product innovations occurring in the world of EN 60849 compliant voice alarm systems. A different approach to the legislation from The Netherlands is opening up and interesting design opportunity.

Voice alarm has rapidly gained traction in many applications as an alternative to traditional emergency sirens. Hybrid public address and voice alarm systems take advantage of the need for standard audio infrastructure for paging and public announcements as well as emergency messages.

However such emergency systems are subject to the European standard EN 60849 or equivalent national standards and so delivering emergency messages over a standard public address systems brings with it all the requirements of backup power supplies, redundant amplification and line monitoring.

The need for such stringent performance regulation and redundancy has meant that emergency systems have been relatively slow to take advantage of digital technologies, however that adoption is now coming on apace with all of the major players employing networking and IP-based technology in their systems.

The latest to join the IP party is TOA. Whilst the company has long been a market leader in PA and VA it only now that it has a fully digital decentralised offering to rival the likes of Bosch’s Praesidio or G+M’s APS systems.

SX—2000 is a fully network-enabled decentralised system for large installation projects such as stadiums. It has already been employed at the Beijing Olympics and is due in Europe this autumn.

The system is modular in nature, like many of its counterparts and consists of the System Manager unit, sitting over a number of audio input and output boxes. It’s a matrix style system with a total of 64 audio inputs and 128 outputs available. Rather than developing its own audio protocol, TOA has elected to license the Cobranet digital audio system to connect remote units. The system controller features full DSP functionality.

Also new from TOA is the VM 3000, this is a fully EN 60849 compliant upgrade to the existing VM 2000 product, designed for smaller scale installations. At its most basic is a six zone control box, with everything needed included. However you can expand to more zones but adding a number of slave modules.

Bosch’s Praesidio has now been on the market for around five years and at its inception was based on digital technology. In the intervening period the company has added hardware modules and software functionality to continue to respond to customer needs. Like TOA, Bosch takes a modular approach with a central control box governing a number of input and output modules and amplifiers.

Product manager Martijn Van Overveld admits that the competition is now fierce: “There are a lot of competitive systems on the market right now. I would say that how we differentiate ourselves from the competition is more that the total package is better. Combining our amplifiers, with the system controllers and our ceiling speakers makes for a much more efficient installation.

The Praesidio system also uses a single cable for both power and signal within a rack. Equipment is connected in a daisy chain arrangement with the bus running down from the controller, through all the amps and then back-up the opposite side of the rack. This immediately introduces redundancy into the system because information (and power) can be distributed in either direction around the bus.

The way the Bosch system handles amplifier redundancy is also rather elegant. Bosch’s new Plena basic amplifiers operate in such a way that if you have a rack of ten, an 11th amplifier can act as the spare for the whole stack. Whilst other manufacturers include a redundant amp in each box, this can start to become prohibitively expensive in very large-scale systems.

British manufacturer Baldwin Boxall’s Vigil 2 product has been in the market for almost 2 years. Sales Director Neil Jarvis feels that one of its distinguishing features is its engineering provenance being a UK-manufactured system. It’s also designed to meet the requirements of BS5839, which are more rigorous than EN60849.

The system’s main component is the BVRD2M system controller, each of which can run a total of 96 zones. These units can be networked almost without limit making the system highly scalable. The message playback unit can be used to serve a number of BVRD2M units, either via direct input or over a dedicated digital audio network, allowing the system to be either centrally served or arranged in a distributed fashion. The Baldwin Boxall network controller is the EVA, which operates a bi-directional ring topology for increased system robustness.

Vigil2 is also compatible with digital audio networking and DSP solutions such as Peavey’s MediaMatrix. An example installation carried out by the DRV Group is Birmingham’s NEC Arena in the UK. Here each exhibition hall is served by a self-sufficient BVRD2M controller and a rack of amplifiers, and then each of the controllers is linked over a MediaMatrix network.

Baldwin Boxall also produces its own control software package and a range of touch panels, which the company can customise for a particular customer depending on its requirements.

In common with many of his competitors Jervis believes that the network is the most important innovation in PA/VA systems at the moment: “The technical challenges of using IP networking have been largely overcome now. The main differences between systems now come down to how they use the network. We prefer to run our protocol on a dedicated network. It uses a fair amount of bandwidth and on a shared network there is more risk of interference or signal delays. Even a couple of milliseconds can lead to messages being played out of sync in different zones, making them unintelligible.” This is of course totally unacceptable in a life safety application.

One manufacturer happy to operate over a shared network is Swiss outfit G+M Elektronik. Michael Roffler, the company’s R&D manager explained why this is possible. “Our protocol only uses 8kb/s per audio channel as the audio is highly compressed.” Whatever network the system uses it also monitors its status at regular intervals, waiting for replies from all nodes.

At one installation at a university in Switzerland, G+M installed separate racks in each of 28 buildings, before linking them over the campus’s existing network infrastructure. The university, along with a lot of other clients these days, were keen to save on personnel costs so the system was monitored from a central control room. Ethernet networks can be a highly robust solution since often there are a number of possible routes between points. Even if one fails, there is the possibility for control and status signals to find another way. However in the event of a total failure, each of the racks is totally self-sufficient and can function whilst cut off.

G+M’s most successful VA product is the modular APS system. Unlike the Bosch and TOA systems it’s not a matrix-based system. “Instead of using a lot of different audio buses, we use a priority system which requires less total channels,” said Roffler.

Another Swiss player in the market is Ateis. Its latest EN 60849 compliant product is the DIVA – a single box compliant voice alarm system. Albert Vanderhout, European Sales Manager for the company described its innovative approach to amplifier redundancy. “DIVA contains two amplifiers. One is a dedicated public address and alarm amplifier and the second is used for background music instead of sitting idle. If the backup is needed, the BGM is then disabled and the amp runs as the spare VA unit.”

The range is available with power outputs up to 480W. To compliment the DIVA unit, Ateis also produces two ranges of amplifiers – the DPA series based on Class D technology and the SPA range of Class AB devices. DIVA itself offers 16 monitored outputs, with two channels over 8 zones for redundancy.

Ateis are also working on IP-based solutions. Using its existing IDA switches, in combination with its LAP network enabled amplifiers customers can now build redundant audio networks over the company’s AteisNet protocol. The company is currently working on IDA 8 a big brother to IDA 4. It will operate 8 channels per unit instead of the current four and is expandable to create a matrix of up to 300x300 channels.

Digital networking solutions are excellent ways of linking distributed racks of amplifiers with each other or a control system, however from amplifier to ceiling speaker is still generally covered by good old fashioned 100v lines. For EN 60849 these speaker runs need to be made of toughened cable. However, in Holland the authorities have now allowed an alternative solution. If the speaker runs are arranged in continuous loop instead of a straight line then the requirement for toughened cable is revoked. This is similar to the legislative requirement for loops of fire detection units. Since standard cable is about 10% of the cost of a fireproof solution this could result in significant cost savings.

G+M are among the companies who have already developed products to address this solution. Their APS-178 Loop device sits on the speaker loop and is attached to the amplifier. It monitors the entire line, and in normal operation is sends the audio signal one way around, treating it like a conventional cable run. If it detects a break in the line the device splits the audio signal and sends it in both directions, avoiding the break. Other devices are placed in each audio zone to detect and isolate short circuits.

If adopted by countries outside The Netherlands, this technical innovation could represent a significant revolution in emergency system design.

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