Q

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Q  (Quantization)

Q-1  (Inverse quantization)

Q  (Quadrature) Signal

One of two color difference signals in the NTSC system. The other signal is the I (In Phase) signal.

QA  (Quality Assurance)

A department which monitors the quality of products going to air. Generates the House Masters by copying External Masters and inserts cuts at logical breaking points in the media in accordance with the channel personality.

QAM  (Quadrature Amplitude Modulation)

Type of modulation for digital signals (DVB-C).  Two signal components, I and Q, are each quantized and modulated onto two orthogonal carriers appropriate for the QAM level (4, 16, 32, 64, 128, 258).  The constellation diagram is obtained by plotting the signal components with I and Q as the coordinate axes.  Therefore, 2, 4, 5, 6, 7 or 8 bits of a data stream are transmitted with one symbol, depending on the QAM level (4, 16, 32, 64, 128, 256).  This type of modulation is used in cable systems and for coding the COFDM single carriers.

QEF  (Quasi Error Free)

Less than one uncorrected error per hour at the input of the MPEG2 decoder.

QPSK  (Quadrature Phase Shift Keying)

Type of modulation for digital signals (DVB-S).  The digital serial signal components, I and Q, directly control phase shift keying.  The constellation diagram with its four discrete sites is obtained by representing the signal components using the I and Q signals as coordinate axes.  Due to the high nonlinear distortion in the satellite channel, this type of modulation is used for satellite transmission.  The 4 discrete states all have the same amplitude, and that is why non-linear amplitude distortions have no affect.

QS  (Quantization scaling)

Quad

 Short for Quadruplex. Analog reel to reel format, industry standard of the 1970s. Also known as 2 . The name relates to the 4 heads mounted on a rotary scanner in quadrature, which replay the image.

Quadruplex

A 2-inch videotape format that employs four playback heads scanning vertically across the width of the tape.

Quad Splitter

A device which compresses the video signal and combines the output of four cameras onto the four quadrants of one monitor. This allows full-frame viewing of four camera outputs with only one monitor.

Quantizer

A processing step which intentionally reduces the precision of DCT coefficients.

Quantizing

The process of converting the voltage level of a signal into digital data before or after the signal has been sampled. In digital imaging, the level of quantizing determines how realistically digital images will be reproduced. The more quantizing levels for each sample, the truer the digital representation will be to the original analog source.

Quantizing Error

Inaccuracies in the digital representation of an analog signal. These errors occur because of limitations in the resolution of the digitizing process.

Quantizing Noise

The noise (deviation of a signal from its original or correct value) which results from the quantization process. In serial digital video, a granular type of noise that occurs only in the presence of a signal.

Quantization

The process of sampling an analog waveform to convert its voltage levels into digital data.

Queue

A waiting area for files, print jobs, messages, or anything else being sent from one computer or device to another. In CuteFTP, for instance, you can put files in the queue, and transfer them all at once at another time.

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