Signal generator
[1] There are many different types of signal generators with different purposes and applications and at varying levels of expense.
Signal generators may be free-standing self-contained instruments, or may be incorporated into more complex automatic test systems.
(Modern devices may use digital signal processing to synthesize waveforms, followed by a digital-to-analog converter, or DAC, to produce an analog output.)
RF (radio frequency) and microwave signal generators are used for testing components, receivers and test systems in a wide variety of applications including cellular communications, WiFi, WiMAX, GPS, audio and video broadcasting, satellite communications, radar and electronic warfare.
RF and microwave signal generators normally have similar features and capabilities, but are differentiated by frequency range.
Analog signal generators based on a sine-wave oscillator were common before the inception of digital electronics, and are still used.
There was a sharp distinction in purpose and design of radio-frequency and audio-frequency signal generators.
Many models offer various types of analog modulation, either as standard equipment or as an optional capability to the base unit.
Applications include checking frequency response of audio equipment, and many uses in the electronic laboratory.
In contrast, military communication systems such as JTRS, which place a great deal of importance on robustness and information security, typically use very proprietary methods.
In addition to the above general-purpose devices, there are several classes of signal generators designed for specific applications.
Pitch generators typically include sine waves over the human hearing range (20 Hz to 20 kHz).
The term synthesizer is used for a device that generates audio signals for music, or that uses slightly more intricate methods.
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).
