E351: Network audio unit for Public Address systems

Transcription

1 : Network audio unit for Public Address systems is an audio, data and contacts transceiver over IP networks. Thus, regarding audio, this unit converts analogue signals to digital and packet them so that they can be transmitted over IP using standard VoIP protocols. The benefits of using these devices in front of the traditional analogue transmission methods are: With our network audio adapter, we are transmitting high quality audio over LAN or Internet. Thus, installation costs are lower. Using Ethernet provides a high degree of flexibility as the only limitation of signals transmission is the available bandwidth. It is very easy to add as many signals as required without changing the existing infrastructure. The installation becomes easier as conventional analogue copper cables are heavy and difficult to handle. Ability to transmit different signals over the same cable: audio, video, RS serial data Each can send audio to up to 5 different destinations. The transmission can be unicast or multicast. Each unit can receive up to 5 prioritized different audio sources. There are 5 priorities and the input with the highest priority will be played. For example, it is possible to send background music from a CD player (after being encoded by ) and announcements from other sources. In the receiver side will be played the source with the highest priority. It has 8 input / output contacts that can be used to enable or disable amplifiers (provided that the amplifier has contacts as well). Thus, we can create different audio zones. Furthermore, with one contact it is possible to activate one audio output (for example, a button in a desktop microphone to begin talking). Alternatively, there are other possible uses typical of security applications: opening or closing gates, access control, switching on / off lights, etc. The configuration of is quite easy so no particular skills are required. There is a very intuitive built-in web server to help configure the unit. With the free Equitel Devices Searcher it is possible to automatically locate all the EQUITEL IP devices in the network and even change some parameters, such as the IP address. It is possible to control it with a management software. Our system is more oriented to the commercial PA sector. Therefore, I will try explaining in brief its basics and functioning so that you may have a clearer idea.

2 DESCRIPTION is a single channel high quality bidirectional audio, single channel asynchronous serial data and 8 ON /OFF contacts transceiver over IP networks (LAN or Internet). This allows an important decrease in the installations costs as it is not necessary to use dedicated lines. This equipment has been specially designed for PA systems. It can be used as well with intercom systems, access control, tunnels and, in general, in those installations where the transmission of high quality audio, serial data or contacts is required. The most important characteristics of the system are as follows: Possibility of high quality transmission of one bidirectional audio signal ( Hz bandwidth, SNR >74 db), either point-to-point or point-multipoint. One RS-232, RS-422 or RS-485 serial data channel (for example, for desktop console with RS serial data connection; external volume controllers; access control; telemetry of cameras, etc). 8 input and 8 output dry contacts (to be associated with zone paging amplifiers, access control, etc.) Easy configuration via Web server or Telnet. Internal firmware update through the Ethernet network. Highly robust: Operating temperature range: -40 to 74 ºC Power supply range: from 12 to 24 Vdc. Consumption: less than 5 W. The data and contacts have 5 senders and 1 receiver, and the audio has 5 senders and 5 receivers. This allows sending the audio, serial data and contacts to up to 5 different destinations at the same time. Also, each unit can receive up to 5 different prioritized audio streams. Likewise, each can be associated to a multicast group. The audio can be configured in different qualities and formats: PCM-law A, sampled at 8 KHz, 8 bits per sample (64 Kbps). Corresponds to the ITUG711 standard, being the common in IP telephony in Europe. It offers a bandwidth between 300 and 3000 Hz and a signal to noise ratio higher than 61 db. PCM sampled at 32 KHz, 16 bits per sample (512 Kbps). Bandwidth: 20 to Hz. Signal to noise ratio: 74 db. PCM sampled at 48 KHz, 16 bits per sample (768 Kbps). Bandwidth: 20 to Hz. Signal to noise ratio: 74 db.

3 Being specially designed for PA systems means, for example, that the 8 output contacts can be used to enable or disable the output amplifiers. This way, with only one unit, we can control up to 8 different audio zones. This is the common use that our customers give to, although obviously, you can use them for anything you need (controlling the switching on /off the lights; gates control; access control ). 1. APPLICATIONS One of the simplest applications is a point to point configuration, in order to extend the audio line: However, considering what is mentioned above, we can imagine that the typical application is with projects where the transmission of multi-point broadcast in remote locations is required: paging, background music, announcements distribution in railway stations, the headquarters of one company addressing to its subsidiaries, airports, university campus, schools, organizations with several buildings (for example, a hospital), etc: Branch 1 HEADQUARTERS Controller Branch 2 IP network Branch 3 The General Manager, for example, can address his employees in different locations using Internet, and they can answer back. In the case of an airport, the same audio announcements can be played in different airport terminals.

4 Likewise, this unit can be used in the same building, in order to control the PA system of the different destinations: On the other hand, the in the control center can be substituted by a PC running the appropriate application:

5 Following this scheme, we can find an endless number of different possibilities where our system can be used. In an auditorium, I can picture the following situation: The audio in the stage is converted by and transmitted over LAN till the waiting room, where other speakers are relaxing or waiting to be called. Depending on the configuration, we can put one amplifier or another to decode the audio signal. However, in the corridors, hall, etc it should be necessary to install an announcement system for the audience and even workers in case of emergency, or to announce that the conference is about to begin or resume, etc. 2. CONCLUSION In summary, this unit is not likely to be used with audio applications requiring low and controlled latency but there are a great number of possible uses: tunnel PA system, paging systems, messaging, music for airports or railway stations, shopping malls Any place you can imagine in which you need to distribute high quality audio over Internet or LAN. Finally, our background is especially in security. Well, our system can also be used in places where microphones are installed along with security cameras to confirm unauthorized entry. So, during business hours, music and messages can be broadcasted to numerous stores in the chain. During after-hours, enables listening in should someone break-in.