As the name suggests, The Signal generator is an electronic equipment which has the ability to produce a Sine-wave signal (Volt) and has a wide range for both frequency/amplitude. It can generate desired signals with a remarkable accuracy. Because of this property, this equipment is utilised to generate desired test-conditions so that it can be evaluated than an electronic equipment is performing optimally or sub-optimally. It may also be utilised to replace the unavailable signal in an equipment that is under analysis / study. Now, you can understand why it has been placed under category of test equipments.
This Signal Generator also carries out the modulation of carrier-frequency. The dial-setting and meter indicates that. This modulation can be of any type i.e. of Sine-wave, Square-wave or Triangular-wave. The o/p of Signal-generator may be Amplitude-modulated / Frequency-modulated. Under normal settings, the o/p is amplitude-modulated.
How it works??
An attenuator is used to maintain the desired signal generation through out the whole duration of the signal’s production. Then, the attenuator’s output is fed to an amplifier which boosts up the signal. While boosting up the signal, the amplifier maintains the signal’s stability and steadiness. Almost every Signal-generator generate signal waves in analog/digital format and functions in audio frequencies ranging from 20hz to 20Khz.
Though, the Amplitude modulation and Frequency Modulation (AM/FM) are the most used modulations in Signal-generator, Yet there are some advanced Signal-generators which includes Q-A-M (Quadrature-amplitude-modulation) also. The Q-A-M format permits the signal transmissions on similar frequency (as an orthogonal-carrier) because of the offsetting of the signal’s angle by 90ᴼ. The demodulation of this sent signal can then be carried out at receiver’s side.
You will be surprised to know that few Signal-generators are often utilised as inverters also (i.e. for converting a DC input to an AC output.)
Normally Signal-generators contains a quartz-crystal for filtering the undesired signals (noises) from the amplifier’s output (Signal generated). Such type of configuration is called Linear-amplifier / Linear-oscillator. Commonly used signal generators consists of frequency-knob and amplitude-knob. By turning the Amplitude/Frequency knobs physically, the desired signal can be adjusted.