What are they talking about?!?
Digital/HDTV Terms that Begin with "C"
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Center Channel
A 6 Mhz (bandwidth) section of broadcasting spectrum allocated for one analog NTSC transmission.
Channel
The center speaker in a home theatre setup. Ideally placed within one or two feet above or below the horizontal plane of the left and right speakers and above or below the display device, unless placed behind a perforated screen. Placement is important, as voices and many effects in a multichannel mix come from this speaker.
Chrominance
The color component of a video signal that includes information about hue (shade) and saturation (intensity).
Coaxial
1) A speaker typically with one driver in the middle of, and one on the same axis as, another driver.
2) An audio or video cable with a single center pin that acts as the hot lead and an outer shield that acts as a ground.
Codec
Mathematical algorithms used to compress large data signals into small spaces with minimal perceived loss of information.
Comb Filter
A comb filter's task is to remove residual chrominance (color) information from the luminance (brightness) signal. Comb filtering enhances fine detail, cleans up image outlines, and eliminates most extraneous colors. Comb filters are not required and not used with S-video or component video connections since those connections carry the chrominance and luminance information separately. There are 4 types of comb filters found in today's TVs:
| Glass - may also be referred to as an "analog" comb filter. 2-Line Digital - compares consecutive scanning lines within one field of video and makes adjustments to reduce cross-color interference. 3-Line Digital - compares 3 scanning lines within a field of video. By comparing more picture information, a 3-line filter further reduces color bleeding and dot crawl. 3D Digital - not only analyzes consecutive scanning lines within a field, but also analyzes the preceding and following fields. Results in improved color purity and a more stable video image, and nearly eliminates dot crawl and color bleeding. Also called 3D Y/C. |
Component Video Connection
The output of a video device (such as a DTV set-top box), or the input of a DTV receiver or monitor consisting of 3 primary color signals: red, green, and blue that together convey all necessary picture information. With current consumer video products, the 3 component signals have been translated into luminance (Y) and two color difference signals (PP, PR), each on a separate wire.
Composite Video
An analog, encoded video signal (such as NTSC) that includes vertical and horizontal synchronizing information. Since both luminance (brightness) and chrominance (color) signals are encoded together, only a single connection wire is needed (i.e. RCA cables).
Compression
A method of electronically reducing the number of bits required to store or transmit data within a specified time or space. The video industry uses several types of compression methods but the method adopted for DTV is called "MPEG2." Four full-range channels of programming and data can be compressed into the same space required by a single analog channel.
Contrast ratio
Measures the difference between the brightest whites and the darkest blacks a display can show. The higher the contrast ratio, the greater the ability of a display to show subtle color details and tolerate ambient room light. Contrast ratio is an important spec for all types of TV display, but especially for front projectors.
Controller
Generic term that typically refers to a combination preamp/surround processor or receiver. Can also refer to a handheld wireless remote.
CRT (Cathode-Ray Tube)
A CRT ("picture tube") is a specialized vacuum tube in which images are created when an electron beam scans back and forth across the back side of a phosphor-coated screen. Each time the beam makes a pass across the screen, it lights up a horizontal line of phosphor dots on the inside of the glass tube. By rapidly drawing hundreds of these lines from the top to the bottom of the screen, images are created.
The regular "direct-view" TVs that most people watch have a single large picture tube, while CRT-based rear-projection and front-projection TVs use three CRTs: one each for red, green, and blue.