Security Dealer & Integrator

NOV 2013

Find news and information for the executive corporate security director, CSO, facility manager and assets protection manager on issues of policy, products, incidents, risk management, threat assessments and preparedness.

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VIDEOSURVEILLANCE teaching tool packages, video conferencing, concert streaming and so on. Plenty of traditional security integrators have harnessed the power of video and audio to create completely separate and successful business units. And as with any conversation today about surveillance technology, the focus often shifts to intelligence. Audio intelligence can tell a camera to record on the sound of a voice, broken glass or a gunshot. It can enact an alarm to sound or alert a business owner to a potential situation. It can even instruct a PTZ camera to focus on a specific area of a scene and track movement. But as with all promises of intelligent analytics, expectations must be properly set and the system must be tested before deployment. Audio Tech Tips Condenser microphones, once relegated to professional recording studios, are now being made by some surveillance manufacturers and thirdparty accessory providers designed specifically for security with discreet and flexible installation options. 38 The first thing to understand is that integrating audio is much easier and less costly with network video as opposed to analog CCT V. Video and audio can be sent over the same cable, which reduces cabling cost and installation effort while helping to better synchronize data. Also, in an analog system, if the distance between the microphone and recording station is too long, balanced audio equipment will be needed — further increasing system cost and installation complexity. When an IP camera or video encoder has support for audio, it typically includes a builtin microphone but rarely a speaker. This is important if you require two-way communications (more on this later). If the device does not have a built-in microphone, then often it will have a line-in jack for an external one. The built-in microphone may be appropriate for some applications, but an external microphone may provide a better solution for applications that require higher quality sound or need to place the microphone at a specific location. There are three main types of microphones: dynamic, condenser and electret. Dynamic microphones are rarely used in surveillance because of poor audio sensitivity and ability to reproduce important low frequencies. If a dynamic microphone is required, typically it will use an XLR connector or, if that is not supported, an adapter. The condenser microphone is known for the highest audio sensitivity and quality. While some back-electret microphones can provide similar quality, the condenser is often used in professional recording studios. Surveillance manufacturers and third-party accessory providers have recently launched new condenser microphones designed specifically for the security world with discreet and flexible installation options. The third option, electret condenser microphones, are typically ones found in headsets and computer microphones — so it is not surprising that these are the types of microphones often built-in to network cameras. This type of microphone normally needs 1-10 Volts to work, which can be powered by the camera itself. A sometimes overlooked audio device for network video applications is the audio module, which enable audio support and I/O ports that can be located far from a network camera. Audio modules, for example, are great for a city surveillance application where a PTZ is located high up on a pole, but the sound should be captured at street level. How to Select Audio Equipment When selecting a camera or encoder for video and audio capabilities, you must determine the type of communication that is important for the application. If the enduser requires two-way communication, then obviously a microphone and speaker (either internal or external) are required. From there, determine which of the three communication options will satisfy the needs: simplex, half-duplex or full-duplex. In simplex mode, audio is sent in one direction only. In half-duplex mode, audio is sent in both directions, but only one party at a time www.SecurityInfoWatch.com | SD&I; | November 2013

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