A video signal generator is a type of signal generator which outputs predetermined video and/or television oscillation waveforms, and other signals used in the synchronization of television devices and to stimulate faults in, or aid in parametric measurements of, television and video systems. There are several different types of video signal generators in widespread use. Regardless of the specific type, the output of a video generator will generally contain synchronization signals appropriate for television, including horizontal and vertical sync pulses (in analog) or sync words (in digital). Generators of composite video signals (such as NTSC and PAL) will also include a colorburst signal as part of the output. Types of video signal generators Video signal generators are primarily classed according to their function. In addition, they may be classified according to the video formats and interface standard they support—one generator may generate composite analog signals (typically NTSC, PAL, or both), another may generate CCIR 601, and a third may generate MPEG streams over an ASI. Many manufacturers sell signal generation platforms, which can be populated with multiple modules providing the above capabilities (and supporting different formats). Many such platforms also include audio generation capability (as television includes audio as well as video), supporting either embedded audio or standalone audio formats. Test signal generators A test signal generator generates test patterns, and other useful test signals, for troubleshooting and analyzing television systems. These devices are generally intended for off-line use (test patterns are seldom broadcast, unless a station is not operating properly or is off the air at the time), as they output complete television signals. Examples of signals output by such a device include: Color bars, one of several test signals used to verify the proper reproduction of a TV system's color gamut, and/or that a television signal or plant is compliant with the appropriate analog transmission standards Flat fields, a signal consisting of nothing but a specific color (typically white, black, a shade of gray, or one of the primary colors (red, green, and blue) at maximum saturation). A red field is especially important in PAL applications, as it is the "red difference" portion of the chroma signal whose phase alternates every line; the red field should appear as a solid block of color, with no visible "bands" going across the screen. Multibursts, sweeps, and pulse signals, used to test the frequency response of a television system Ramp signals