Detection of widescreen signalling (WSS) from a broadcaster. Allows broadcaster to configure television to proper aspect ratio.

Improved Definition TeleVision. Television transmitters and receivers that (a) are built to satisfy performance requirements over and above those required by the NTSC standard and (b) remain within the general parameters of NTSC standard emissions. Note 1: IDTV improvements may be made at the TV transmitter or the receiver. Note 2: Examples of improvements include enhancements in encoding, digital filtering, scan interpolation, interlaced line scanning, and ghost cancellation. Note 3: IDTV allows the TV signal to be transmitted and received in the standard 4:3 aspect ratio. Synonym enhanced-quality television.

Institute of Electrical and Electronics Engineers. An international, non-profit, technical organization based in the U.S. that develops standards.

Also called FireWire or iLink. A serial bus which can address up to 63 devices, communicating at up to 400Mbps but is limited to a cable length of 4.5 meters. Its content copy protection scheme is called DTCP or 5C. Most DV camcorders have a IEEE 1394 port as well as D-VHS VCRs and some set-top boxes for cable and satellite.

High speed serial bus with a speed up to 400Mbps. See IEEE 1394.

In audio, a particular system’s ability to reproduce sound so that it seems to be coming from a particular location.

Total inductance, resistance or reactance to a signal flow. Reactance is like inertia where acceleration takes time to get going and time to stop but there isn’t a net loss in energy. Resistance on the other hand, translates electricity into acceleration or heat. Impedance is measured the same as resistance, in Ohms.

An infra-red (IR) remote control transmits in the spectrum of infra-red light, such as a television remote. Unlike RF remotes, IR remotes must point at the receiver (line of sight). Typical range is limited to 30 feet including the distance to and from reflected surfaces. For example, if you are controlling a projector and you point the remote at the screen which is 12 feet from you and the projector is 10 feet, the total distance is 22 feet. Most projectors have a IR sensor in both the front and rear of the projector, whereas, flatscreens generally have a single IR sensor in the front of the unit. When working at or near the maximum distance, pointing right at the receiver is necessary. IR remotes must have clear path or reflected path to the receiver to operate.

A process where a video image is delivered in two fields each containing half the video image rather than a single frame that contains the entire image. The first field contains all the odd lines and the second field contains all the even lines. For example, each 480i frame is made up of two fields of 263 and 262 lines of resolution and updated at 60Hz. 480 denotes the active picture area; however, the total frame size is actually 525 lines. 480i and 1080i are interlaced signals whereas 720p is a progressive signal where each video image is delivered in a single frame. Interlaced video was introduced with the first televisions because of bandwidth limitations.

A unit that can operate under a international selection of power requirements. The specs of units vary widely, but the minimum is 105-230 volts, and 50-60 cycles AC (alternating current). If you see a specification like 110v, 220v instead of a range, those ratings are usually +/- a given percent such as 10%. Most units are "self-switching" they will automatically switch to whatever power source you plug it into. Others will have to be switched (internally or externally to accommodate a difference voltage or cycle range.

The non-picture area between pixels in a fixed-pixel display. Commonly called screen door effect when noticeable. Also relates to fill rate, a measurement that describes this characteristic. For example, a D-ILA projection system has a fill rate of 93%, which indicates a smooth image and has a small interpixel gap.

Invert image flips the image from top to bottom, to compensate for ceiling mounting a projector upside down. Projectors typically ceiling-mount upside down, because most have a built-in offset that allows you to mount the screen at a comfortable height, yet still project an image without tilting the projector and causing keystone distortion.

Imaging Science Foundation. Organization that trains and accredits display calibration technicians as well as certifies display hardware. Designs standard testing and calibration procedures and tools.