The Abcs of AV

BICSInews MAGAZINE november/december 2012 volume 33, number 6 + ITS in Wet Locations + AV Connectivity + Passive Optical LAN Design + 2013 BICSI Board Election Results technology innovation& When deploying AV systems, it is important to know what type of connections your AV equipment requires, what type of cabling media is required and what the distance limitations might be for the specific application, type of signal and bandwidth. The ABCs of AV by Glenn Kierstead Every enterprise environment today relies on audiovisual (AV) and multimedia technolo- gies for a variety of applications, from video conferencing and training, to entertainment, digital signage, broadcasting and sound systems. With the need to access and view video content becoming as vital as the need Glenn Kierstead is a senior to access email and the local area network product manager for copper (LAN), AV applications are now tightly systems at Hubbell Premise Wiring and responsible for embedded into everyday business activities in developing and marketing LAN and AV connectivity solutions. corporate, education, health care, hospitality, Glenn can be reached at [email protected]. retail and entertainment market segments. Analog Audio Digital Audio Dolby Digital 5.1 Composite Video Video Component 480p, 720i, White – left channel Multichannel bit Six-channel sound Transmits video over Transmits video over Red – right channel stream (surround with left (white), right one cable (480i and three cables, including 1080p, What? sound after decoding). (red), surround left 480p). Typically color luminance (Y), Typically color (white), surround coded yellow. red chrominance (Pr) If you are not familiar with how picture coded orange. right (red), center and blue chrominance (black) and low- (Pb). Y is typically quality is achieved, all of those numbers frequency effects green, Pr red, and and the “p” or “i” listed for various display (black). Pb blue. resolutions can be confusing. The display resolution indicates the number of pixels Table 1: Common RCA connector types (i.e., smallest picture element) that can be displayed—the higher the number, the better Whether it is video conferencing equipment in the corporate office, the resolution. The “i” and “p” designate the projector systems and interactive SMART® Boards in the classroom, flat panel type of video—interlaced or progressive. displays and medical AV equipment in a hospital, amplifiers and speaker Interlacing is a technique of rendering systems in the auditorium or security and surveillance equipment at the mall, video by generating two fields of lines— navigating the wide variety of AV applications, equipment and connections a field of odd lines and a field of even lines. is no easy task for the information technology systems (ITS) professional. It was designed specifically for old cathode Identifying the wide variety of AV connectors and understanding key ray tube (CRT) TVs to improve quality deployment considerations can help ease AV system deployment. (i.e., reduce flicker) without consuming extra Know Your Connectivity bandwidth. When an interlaced image is transmitted, half of the lines of an image To the untrained eye, the number and types of AV connectors on the are displayed at one time, alternating back of any AV equipment can be overwhelming. As technology advances, between odd and even lines. The lines are new digital connector types for better sound and picture quality are added to refreshed at about 30 frames per second to the mix. Those new to deploying AV systems may wonder which connectors allow the human eye to interpret them as a should be used for which application. Whether for analog or digital, audio or complete image. video, knowing the use and application of each connector type can help you Progressive, or noninterlaced, scanning make the right decisions. renders video where all the lines of each frame are drawn from top to bottom, rather designs that do not maintain precise that divided into separate fields. Each line impedance for video. While common of the image is displayed one at a time in older home theatre applications, in perfect sequence. While this provides they are rarely used in professional a better quality picture, it requires more video applications. The various colors bandwidth. of RCA connections are related to their While interlaced scanning consumes application, as shown in Table 1. less bandwidth than progressive and RCA connectors—Found on most interlaced devices are typically less complex consumer electronics (e.g., home and less expensive, the images are prone theater equipment), audio equipment, to anomalies, especially video of a fast- computers and video recorders, moving object. To counter the problem, the RCA connector is a standard interlaced images are sometimes blurred, analog, low-level connector that Speaker terminals—Used for which results in a reduced picture quality. features a single cylindrical metal surround sound speakers in home On large displays, interlaced scanning also rod and an outer round metal belt. theater applications, speaker terminals can cause flicker. Progressive scanning The connector gets its name from are quick release spring-loaded push- produces no anomalies or blurring for a the RCA® Corporation, which first button terminals for terminating much clearer picture. While it required used the connection on radios and bare speaker wire or pin connectors. too much bandwidth for traditional phonographs in the 1940s. Used for Speaker terminals with bare wire do analog signals, the shift digital has composite video, component video, not provide as solid a connection made progressive scanning more popular. line-level audio and Sony®/ Philips® or as much protection against short Progressive scanning is also ideal for digital interconnect format (S/PDIF), circuits as wires terminated with advanced video surveillance because it RCA connections are unbalanced connectors. enables more detailed viewing of moving objects. Electronic reprint with permission from BICSI News Magazine-November/December 2012 Issue applications and video entertainment systems. Typically machined as threaded to be screwed into place, the connector is round and features a Binding posts and banana single thin metal shaft in the center. F-type connectors transmit both connections—These connectors Three-pin XLR—Found on PA and audio and video. are typically found on loudspeakers, intercom equipment, amplifiers, amplifiers, home theater equipment component units and microphones and electronic test equipment. in professional broadcasting and Binding posts are a high-quality auditorium applications, the three- connector that can accept several pin XLR connector is the standard types of speaker wire and connec- connector for digital and analog S-video connectors—Used for tions, including banana plugs. They balanced interconnections between standard definition (480i or 576i) contain a threaded metal rod and audio equipment. These durable, analog video distribution in home a cap that screws down on the rod. balanced connections use three theater and entertainment systems Banana plugs consist of a single fat conductors (positive, negative and like DVD players and game boxes, as shaft that bulges on the sides, hence ground) for impedance-balanced lines well as for video cameras, projectors the name. Banana terminations with resistance to electromagnetic and surveillance systems, the S-video provide the most contact area interference (EMI), resulting in low connector is a keyed four-pin mini- of any speaker wire termination distortion. for maximum signal and power DIN connector. The connector transmission. carries luminance (brightness) and chrominance (color), with each signal pin paired with its own ground pin. By separating the color from the brightness, distortions can be eliminated and a better picture SpeakON® connections— quality produced. Stereo jacks (TRS connectors)— Intended solely for high-current Originally invented for telephone audio applications, such as for switchboards, tip, ring, sleeve (TRS) connecting loudspeakers to connectors are commonly known amplifiers in entertainment and PA as stereo jacks. They are the most systems, SpeakON connectors are an common audio interfaces and come alternative to 6.3 mm (0.25 in) stereo BNC connectors—A professional in three sizes. The 3.5 millimeter jacks and XLR connectors. Designed coaxial cable termination used (mm [0.138 inch (in)]) jack is used with a locking system for either primarily in professional studios as for speakers, microphones and soldered or screw-type connections, an interconnect, the BNC connector headphones found on computers, these connectors are less prone to has a thin central pin and an outer portable devices and other consumer disconnection and are fully shielded rounded metal belt. The connector electronics. Typically mounted in to prevent risk of electric shock and pushes onto its jack and twists to panels, the 6.3 mm (0.25 in) jack is short circuits. used for broadcasting and recording the side to lock in place. Primarily equipment, intercom and public used for entertainment, surveillance address (PA) systems, switchboards, systems, wireless systems and test medical testing equipment equipment, BNC plugs have good and industrial and military impedance characteristics. communications equipment. The F-type connectors—Used with miniature 2.5 mm (0.10 in) version coaxial cable, the F-type connector was originally designed for transistor is widely used for cable and satellite radios and

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