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- Number of terms: 20560
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Tektronix provides test and measurement instruments, solutions and services for the computer, semiconductor, military/aerospace, consumer electronics and education industries worldwide.
Fast rise time square waves cannot be used for testing bandwidth-limited systems because attenuation and phase shift of out-of-band components will cause ringing in the output pulse. These outof- band distortions can obscure the in-band distortions that are of interest.
Sine-squared pulses are bandwidth limited and are useful for testing bandwidth- limited television systems. ‘’’Description of the Pulse:’’’ Sine-squared pulses look like one cycle of a sine wave as shown. Mathematically, a sinesquared wave is obtained by squaring a half-cycle of a sine wave.
Physically, the pulse is generated by passing an impulse through a sinesquared shaping filter.
‘’’T Intervals:’’’ Sine-squared pulses are specified in terms of half amplitude duration (HAD) which is the pulse width measured at the 50% pulse amplitude points. Pulses with HADs which are multiples of the time interval T are used to test bandwidth limited systems. T, 2T, and 12.5T pulses are common examples. T is the Nyquist interval, or 1/2 fc where fc is the cutoff frequency of the system to be measured. For NTSC, fc is taken to be 4 MHz, thus T is 125 nsec.
‘’’T Steps:’’’ The rise times of transitions to a constant luminance level (such as the white bar) are also specified in terms of T. A T step has a 10% to 90% rise time of nominally 125 nsec, while a 2T step has a rise time of 250 nsec. Refer to the figure below.
‘’’Energy Distribution:’’’ Sine-squared pulses possess negligible energy at frequencies above f = 1/HAD. The amplitude of the envelope of the frequency spectrum at 1/(2 HAD) is one-half of the amplitude at zero frequency.
Industry:Software
Texture mapping is made possible by full colour mode.
Texture mapping refers to the process of covering the surface of a polygon with values what come from a “texture” that come from some picture stored elsewhere in the system, say a scanned in image.
Industry:Software
Pictures that are coded with respect to the nearest previous I- or P-picture. This technique is termed forward prediction. P-pictures provide more compression than I-pictures and serve as a reference for future P-pictures or B-pictures.
P-pictures can propagate coding errors when P-pictures (or B-pictures) are predicted from prior P-pictures where the prediction is flawed.
Industry:Software
The maximum intrinsic flux density possible in a sample of magnetic material. The intrinsic flux density asymptotically approaches the saturation flux density as the magnetising field strength is increased. A magnetising field strength in excess of 5000 Oe is necessary to obtain an accurate measure of the saturation flux density of a typical tape.
Industry:Software
A DVD half-disc. Two substrates, each 0.6 mm thick, are bonded together to form a 1.2 mm thick DVD disc.
Industry:Software
A term describing the precedence of an effect or key. The “stream” of video through a switcher allows multiple layers of effects to be accomplished, with each successive layer appearing on top of the previous one. A module or effect whose video priority is lower, or underneath subsequent modules or effects is said to be upstream.
Industry:Software
A mechanism that allows control over what viewers may see depending on the settings in the DVD player, the parental code on a DVD, and the structure of the material on the DVD. This is especially useful for youthful viewers whose parents wish to exercise a degree of control over what their children can watch.
Industry:Software
The signal-to-weighted noise ratio is the ratio in decibels, of the nominal amplitude of the luminance signal (100 IRE units) to the RMS amplitude of the noise measured at the receiving end after band limiting and weighting with a specified network. The measurement should be made with an instrument having, in terms of power, a time constant or integrating time of 0.4 seconds.
Industry:Software
Logic device whose output can be placed into a highimpedance (off) state, in addition to the usual high and low states. This feature allows more than one device output to be connected to the same logic node. Three-state operation is a fundamental requirement for devices used on microprocessor data buses. Same as Tri-State (registered trademark).
Industry:Software
