New Bosch Public Address and Voice Alarm System goes IP

PRAESENSA, Bosch has set a new standard in Public Address and Voice Alarm systems. With all system elements being IP‑connected and using state‑of‑the‑art technologies, this system combines cost efficiency and audio quality with ease of installation, integration and use. IP‑connectivity and amplifier power partitioning enable new levels of scalability and adaptability, and combined with local backup power facilities this makes PRAESENSA equally suited to both centralized and decentralized topologies. PRAESENSA uses only a few different but very flexible system devices, each with unique capabilities, to create sound systems of all sizes for an extremely wide range of applications. PRAESENSA fits to an office with background music in the reception area and some occasional calls, as well as to an international airport with many simultaneous (automated) announcements for flight information, and carefully selected music programs in lounges, restaurants and bars. In all cases, it can be installed to operate also as a certified voice alarm system for mass notification and evacuation. System functions are defined and configured in software and system capabilities can be enhanced via software upgrades. PRAESENSA: one system, endless options.

High level system characteristics Secure IP‑infrastructure – PRAESENSA is a networked sound system in which all system elements are connected to OMNEO. Built upon multiple technologies, including IP and open public standards, OMNEO supports AES67 and Audinate's Dante for audio communication and AES70 for system control, with additional network security implemented using AES128 and TLS, offering real‑time authentication and audio encryption on IP as protection against malicious attacks.

OMNEO offers a mature, professional‑grade media networking solution that provides interoperability, unique features for easier installation, better performance, and greater scalability than any other IP offering on the market. Effective power utilization

PRAESENSA multi‑channel power amplifiers have the unique capability of power partitioning, the total power budget of the amplifier can be freely shared across the output channels.

The class‑D amplifier channels operate at high power supply voltages for direct drive 70 V or 100 V outputs without the need for output transformers that would limit the maximum output power of a channel. This also improves efficiency and audio performance and lowers the weight and size of the amplifier. Galvanic isolation of the amplifier outputs, as required by EN 54‑16 and other emergency sound standards, is provided by isolated DC/ DC converters and the isolated Ethernet connections. The amplifier channels have a load independent, flat frequency response that accept loudspeaker loads between zero and full load. Each channel serves a separate zone or part of a zone.

The total amount of output power is defined by the redundant power supply and the heat sink, and because both are shared between the amplifier channels, it doesn't matter how many loudspeakers are connected to each channel, as long as the total combined load does not exceed the maximum of 600 W for the whole amplifier and a load > 300 W is not connected to any other channel than channel 1. A spare amplifier channel is also included to take over a failing channel, a very cost- and space‑effective redundancy measure because this spare channel uses the same redundant power supply and heat sink too. – The flexibility of variable output power for each channel makes it possible to utilize most of the available amplifier power. Traditional multi‑channel amplifiers have a fixed maximum output power per channel. If a channel is not fully loaded, or even not used, the remaining power capability of that channel cannot be claimed by one of the other channels. PRAESENSA systems typically only need half the amount of amplifier power compared to systems with traditional fixed maximum power amplifiers, saving on space, energy and cost. Highest system availability

PRAESENSA offers the highest system availability due to conservative derating of all components, supervision of all critical signal paths and functions, and built‑in redundancy of all critical system elements. PRAESENSA devices have high margins for safety and temperature stability. This is illustrated by the fact that PRAESENSA devices are quite unique in that they may be operated at altitudes of up to 5000 m (16404 ft), an important requirement in Peru, Chile, India, China and other countries. At this altitude the air is less dense and the cooling capacity of air is decreased, making heat removal less effective. Also, the dielectric properties of air change with altitude, decreasing its insulator capabilities. PRAESENSA uses effective heat sinking and significantly increased creepage and clearance distances to maintain safety ratings. – All system devices use dual Ethernet ports, supporting RSTP, to recover automatically from a broken network link.

The multifunction power supply offers battery backup facilities to be insensitive to mains failures.

Amplifiers have an integrated spare amplifier channel to take over from a failing channel automatically. They also have double power supplies built in, working in tandem to minimize stress on components, while each one is capable of supplying full power to the amplifier if one section would fail.

The amplifiers have two loudspeaker outputs per channel, group A and B, separately supervised and protected, to support connection of interleaving loudspeaker strings in the same zone, so a shorted or interrupted loudspeaker line will not mute that zone completely.

Optimized user experience – The PRAESENSA call stations provide a combination of a large touch screen LCD with mechanical buttons and LED indicators. Access to system functions and areas can be configured per call station, to provide exactly the functions the operator needs, not more, not less. The user interface has been developed in cooperation with real users and addresses their needs, but also their discomforts when making calls to zones they can't see or hear, or adjusting the volume of background music in these areas.

Functions are easily selected from the touch screen, and zones are easily selected via keypad keys with LEDs giving immediate feedback on the actual status of that zone. After starting a call, the screen shows the operator the progress of the call, indicating when to speak after a start tone or automatic introduction message has finished, and showing whether the call was successfully completed in all destinations.

Fully-featured as standard – PRAESENSA is an advanced system for Public Address and Voice Alarm purposes. The system consists of a limited range of hardware devices in combination with software to create the required functions. Because the hardware devices are very complete and flexible to use, only a few different devices are sufficient to create a system. For instance, all call stations and amplifiers have a built-in DSP for sound processing, the amplifiers have flexible output power per channel and a built‑in spare channel, the power supply has a built‑in battery charger, and so on. No need for separate add‑ons.

System functions are software based and regularly updates become available to extend the set of capabilities.

Scalable and flexible – PRAESENSA is an extremely scalable and flexible system. All devices are network connected and offer loop‑through connectivity for easy system expansion and RSTP to create a fail-safe network loop. System devices can be decentralized and their redundant loop wiring often allows for cheap non fire‑resistant network cables to be used.

PRAESENSA uses dynamic channel allocation. Because devices do not use static routing, amplifiers and call stations do not have a permanent audio connection to the system controller. That approach would limit the number of devices, since an 8‑channel amplifier would at least need 8 connections, 100 amplifiers would need 800 connections to be independent. Instead, PRAESENSA uses dynamic OMNEO connections that are generated on the fly when needed and freed up after use. Dynamic streams occupy the least bandwidth; if there is no audio transport going on, the channels are simply not there.

Furthermore, this is a scalable solution compared to static channels, which are limited to the number of interconnections that can be handled by the device that contains the audio matrix. All OMNEO audio streams are set up as multicast, directly from the source (the transmitting device, such as a call station) to the destinations (the receiving devices, such as amplifier channels). This connection is setup by the system controller using OCA (AES70). The audio matrix is in the network itself, not in a single unit. In this way, there is no real limitation on the number of source and destination devices. The only limitation is on the number of simultaneous (different) audio streams, which is above 100 and more than enough for even the busiest applications.

Multifunction power supplies have an integrated battery charger for single 12 V battery based backup power, facilitating easy system decentralization. Amplifiers can be placed closer to the loudspeakers, reducing loudspeaker cabling costs, which is especially advantageous in case of expensive fire-resistant loudspeaker cables.

DSP power is available in all call stations and amplifiers, so DSP power grows with every device added to the system.

Every zone has its own amplifier channel for dedicated audio content. Users can make personal music and volume selections, while announcement levels are not affected and loudspeaker line supervision is not impaired. The amplifier's built‑in DSP allows the sound in each zone to be adjusted to the needs and taste of the audience in that area.

The complexities of traditional system planning make little room for error or last‑minute changes. With PRAESENSA however, flexibility is built‑in, allowing for an agile and adaptive approach to planning. PRAESENSA allows for future changes to the areas covered by the system, with minimal or no equipment changes. Thus, initial planning is less sensitive to later small changes, which could impact profitability.