page_title: Signal generator
section_title: Analog signal generators
hierarchical_section_title: Signal generator / General purpose signal generators / RF and microwave signal generators / Analog signal generators
caption_attribution_description: English: E8257D PSG Analog Signal Generator
context_page_description: A signal generator is one of a class of electronic devices that generates electronic signals with set properties of amplitude, frequency, and wave shape. These generated signals are used as a stimulus for electronic measurements, typically used in designing, testing, troubleshooting, and repairing electronic or electroacoustic devices, though it often has artistic uses as well.
  There are many different types of signal generators with different purposes and applications and at varying levels of expense. These types include function generators, RF and microwave signal generators, pitch generators, arbitrary waveform generators, digital pattern generators, and frequency generators. In general, no device is suitable for all possible applications.
  A signal generator may be as simple as an oscillator with calibrated frequency and amplitude. More general-purpose signal generators allow control of all the characteristics of a signal. Modern general-purpose signal generators will have a microprocessor control and may also permit control from a personal computer.
context_section_description: 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.
  RF
  RF signal generators produce continuous wave radio frequency signals of defined, adjustable,  amplitude and frequency. Many models offer various types of analog modulation, either as standard equipment or as an optional capability to the base unit. This could include AM, FM, ΦM (phase modulation) and pulse modulation. A common feature is an attenuator vary the signal’s output power. Depending on the manufacturer and model, output powers can range from -135 to +30 dBm. A wide range of output power is desirable, since different applications require different amounts of signal power. For example, if a signal has to travel through a very long cable out to an antenna, a high output signal may be needed to overcome the losses through the cable and still have sufficient power at the antenna. But when testing receiver sensitivity, a low signal level is required to see how the receiver behaves under low signal-to-noise conditions.
  RF signal generators are available as benchtop instruments, rackmount instruments, embeddable modules and in card-level formats. Mobile, field-testing and airborne applications benefit from lighter, battery-operated platforms.  In automated and production testing, web-browser access, which allows multi-source control, and faster frequency switching speeds improve test times and throughput.
  RF signal generators are required for servicing and setting up radio receivers, and are used for professional RF applications.
  AF
  Audio-frequency signal generators generate signals in the audio-frequency range and above. An early example was the HP200A Audio Oscillator, the first product sold by the Hewlett-Packard Company in 1939. Applications include checking frequency response of audio equipment, and many uses in the electronic laboratory.
  Equipment distortion can be measured using a very-low-distortion audio generator as the signal source, with appropriate equipment to measure output distortion harmonic-by-harmonic with a wave analyser, or simply total harmonic distortion. A distortion of 0.0001% can be achieved by an audio signal generator with a relatively simple circuit.
caption: An analog RF signal generator
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