Editing Signal generator (section)

== Special purpose signal generators ==
[[File:Tone-generator-and-wire-tracker-0a.jpg|thumb|right|A pitch generator and a probe for locating a specific pair of wires amongst many, for example in a [[punch block]].]]

In addition to the above general-purpose devices, there are several classes of signal generators designed for specific applications.

=== Pitch generators and audio generators ===

A pitch generator is a type of signal generator optimized for use in [[sound reproduction|audio]] and [[acoustics]] applications. Pitch generators typically include sine waves over the human hearing range (20 [[Hertz|Hz]] to 20&nbsp;kHz). Sophisticated pitch generators will also include sweep generators (a function which varies the output frequency over a range, in order to make frequency-domain measurements), multipitch generators (which output several pitches simultaneously, and are used to check for [[intermodulation distortion]] and other non-linear effects), and tone bursts (used to measure response to transients). Pitch generators are typically used in conjunction with [[sound level meter]]s, when measuring the acoustics of a room or a sound reproduction system, and/or with oscilloscopes or specialized audio analyzers.

Many pitch generators operate in the [[Digital data|digital]] domain, producing output in various digital audio formats such as [[AES3]], or [[SPDIF]]. Such generators may include special signals to stimulate various digital effects and problems, such as [[Clipping (signal processing)|clipping]], [[jitter]], [[bit error]]s; they also often provide ways to manipulate the [[metadata]] associated with digital audio formats.

The term [[synthesizer]] is used for a device that generates audio signals for music, or that uses slightly more intricate methods.

==== Computer programs ====
[[Computer program]]s can be used to generate arbitrary waveforms on a general-purpose computer and output the waveform via an output interface. Such programs may be provided commercially or be freeware. Simple systems use a standard computer [[sound card]] as output device, limiting the accuracy of the output waveform and limiting frequency to lie within the [[audio-frequency]] band.

=== Video signal generator ===
{{main|Video signal generator}}
A video signal generator is a device which outputs predetermined video and/or television waveforms, and other signals used 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. Video signal generators are available for a wide variety of applications and for a wide variety of digital formats; many of these also include audio generation capability (as the audio track is an important part of any video or television program or motion picture).