Signal waveform analysing instruments

Waveform Analyzing Instruments:


The analysis of electrical signals is used in different applications. The different instruments used for signal analysis are wave analyses, distortion analysers, spectrum analysers, audio analysers, and modulation analysers.

All signal analysis instruments measure the basic frequency properties, but they use different techniques to do so. A spectrum analyser sweeps the signal frequency band and displays a plot of amplitude versus frequency. It has operating range of 0.02 Hz to 250 GHz. A wave analyser is a voltmeter which measures the amplitude of a signal frequency within a band of about 10 Hz – 40MHz.

A) Wave Analysers :

Analysis of the waveform means determination of the values of amplitude, frequency and sometime phase angle of the harmonic components.

A wave analyser is an instrument designed to measure relative amplitude of signal frequency components in a complex waveform .basically a wave instruments acts as a frequency selective voltmeter which is tuned to the frequency of one signal while rejecting all other signal components.

Types of wave analysers:

There are two types of wave analysers, depending upon the frequency ranges used,

a) Frequency selecting wave analyser.

b) Heterodyne wave analyser.

B) Harmonic distortion analyser :

The application of the sinusoidal input signal to an electronic device , such as amplifier should result in generation of a sinusoidal output waveform .generally the output is not exactly as the input i.e. it is not exactly sinusoidal because of various types of distortion may occur. Non linear behavior of circuit elements introduces harmonics in the output waveform and the resultant distortion is often referred as harmonic distortion.

Types of distortion analyzer :

  1. Frequency distortion

  2. Phase distortion

  3. Amplitude distortion

  4. Intermodulation distortion

  5. Cross-over distortion.

C) Spectrum analyzers :

A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals. The input signal a spectrum analyzer measures is electrical, however, spectral compositions of other signals, such as acoustic pressure waves and optical light waves, can be considered through the use of an appropriate transducer.

Types of Spectrum analysers :

Spectrum analyzer types are dictated by the methods used to obtain the spectrum of a signal. There are 1)swept-tuned and

2) FFT based spectrum analyzers.

D) Audio Analyser

An Audio Analyser is a test and measurement instrument used to objectively quantify the audio performance of electronic and electro-acoustical devices. Audio quality metrics cover a wide variety of parameters, including level, gain, noise, harmonic and intermodulation distortion, frequency response, relative phase of signals, interchange crosstalk, and more. In addition, many manufacturers have requirements for behavior and connectivity of audio devices that require specific tests and confirmations.

Audio analysis requires that the device under test receive a stimulus signal of known characteristics, with which the output signal (response) may be compared by the analyzer in order to determine differences expressed in the specific measurements. This signal may be generated or controlled by the analyzer itself or may come from another source (e.g., a recording) as long as characteristics relative to the desired measurement are defined.

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