What is a Wave Analyzer and Its Working

The waveform analysis can be mainly done to determine the values of harmonic components like frequency, amplitude & phase angle sometimes. In a complex waveform, this device plays a key role to measure relative amplitude for components that have a single frequency. Generally, this analyzer works as a frequency selective voltmeter and it is used for one signal frequency when refusing all other signal components. The operating frequency range of this device is in the MHz range. This device is used in industries for reducing the sound as well as vibrations that are produced through electrical machines while rotating. This article discusses an overview of wave analyzer.

What is a Wave Analyzer?

Wave Analyzer Definition: It is an electronic device, used to analyze waveforms. It is also known as a signal analyzer because both the terms signal and wave can be used frequently by interchanging them. The periodic signal can be represented through the two terms like the dc component and series of sinusoidal harmonics. The periodic signal analysis is nothing but the analysis of the harmonics components that exist in it.

Wave Analyzer Instrument
Wave Analyzer Instrument

Alternative names of this analyzer are carrier frequency, frequency selective, or selective level voltmeters. The tuning of this device can be done with the frequency of the component whose amplitude needs to be measured. These analyzers are applicable in the low radio frequency range under 50MHz and it provides an extremely high-frequency resolution.

Types of Wave Analyzer

These are classified into different types like the following.

Basic Wave Analyzer

Based upon Frequency Ranges

  • Heterodyne Wave Analyzer
  • Frequency Selective Wave Analyzer

Basic Wave Analyzer Block Diagram

The block diagram of this is shown below where the function of each block is discussed below.

Block Diagram of Wave Analyzer
Block Diagram of Wave Analyzer

Primary Detector

The first block of this analyzer is the primary detector. This detector includes an LC circuit where the values of capacitor and inductor of this circuit can be adjusted to allow the preferred harmonic frequency component simply that is to be calculated.

Full Wave Rectifier

A full-wave rectifier is a center block of the analyzer and the main function of this is to change the AC i/p into a DC o/p. It gets the standard value of the i/p signal.

PMMC Galvanometer

It is the final block of the analyzer and it is used to display the signal peak value which is attained from the o/p of the rectifier. This full-wave rectifier is used to provide the average input value. And, several tuned filters are used to this final block through a selector switch.

The basic circuit diagram of the wave analyzer is shown below. The designing of this circuit can be done by replacing each block with the required components which are shown in the circuit diagram.
This basic circuit is mainly used to analyze each & every component of harmonic frequency in a periodic signal.

Wave Analyzer Circuit Diagram
Wave Analyzer Circuit Diagram

Based upon Frequency Ranges

These are classified into two types based on the frequency range which include the following.

  • Frequency Selective Wave Analyzer
  • Heterodyne Wave Analyzer

Frequency Selective Wave Analyzer

The working principle of the frequency selective wave analyzer is, it works on the frequency-selective voltmeter principle. It is tuned to the one signal frequency as well as rejects all other kinds of signal components. This kind of analyzer includes a narrow passband filter section to tune the frequency.

This kind of analyzer is mainly used to measure the frequency range of audio that ranges from 20Hz-20 kHz. The frequency selective wave analyzer block diagram is shown below which includes different blocks where each block and its function is discussed below.

Frequency Selective Type
Frequency Selective Type

Input Attenuator

This is the primary block in this type of wave analyzer. The AF signal is applied to the input attenuator to analyze. So, when the amplitude of the signal is very large then the input attenuator will attenuate the signal.

Driver Amplifier

The main function of the driver amplifier is to change the signal which is received once required.

High Q-filter

The main function of a high Q-filter is, it allows the required frequency as well as rejects unnecessary frequencies. This kind of filter includes two RC sections as well as two filter amplifiers.

These two sections will be cascaded by each other. Here, the capacitance values can be changed to change the frequency range in powers of 10. Likewise, we can change the values of resistance to change the frequency in a preferred range.

Meter Range Attenuator

This attenuator obtains the preferred AF signal like an input to generate an attenuated output when it required.

Output Amplifier

An output amplifier is used to change the received AF signal if it is required.

Output Buffer

The output buffer is mainly used for providing the preferred AF signal to o/p devices.

Meter Circuit

This circuit is used to display the reading of the preferred AF signal and the selection of the meter reading can be done in decibel range otherwise volt range.

Heterodyne Wave Analyzer

The heterodyne wave analyzer mainly works on the mixing or heterodyning principle. Here heterodyned is the input signal which is to be analyzed that is, mixing to a high IF signal through an internal local oscillator. The components of signal frequency move into the IF amplifier’s passband due to the oscillator tuning.

Heterodyne Type
Heterodyne Type

The IF amplifier output can be rectified to be given to the metering circuit. The wave analyzer which is mainly used to analyze the signals in the RF range is known as the heterodyne wave analyzer. So, the block diagram of the heterodyne wave analyzer is shown below where each block and its working is discussed below.

For the first block like the input attenuator, the RF signal is given to analyze the signal. If the amplitude of the signal is very large then the signal can be attenuated using an input attenuator.

The untuned amplifier is the second block in the wave analyzer which is used to amplify the RF signal when it is required & it is given to the primary mixer.

Both the RF signal frequency as well as local oscillator output ranges from 0 to 18 MHz and 30 to 48 MHz correspondingly. So, the primary mixer which generates an output has 30 MHz of frequency. This is the main disparity of two signal frequencies that are applied to it.

IF amplifier is used to amplify the IF signal (Intermediate Frequency), that is. the o/p of the primary mixer. After that, the IF signals which are to amplify can be given to the next mixer.

Both the frequencies of the amplified intermediate frequency signal as well as crystal oscillator is similar to 30MHz. Thus, the next mixer generates an output with a 0 Hz frequency. This is the main dissimilarity of frequencies for two applied signals.

The active LPF can be selected with a frequency of 1500 Hz. Therefore, this filter allows the second mixer’s output signal.

Finally, a meter circuit is used to display the RF signal’s reading. This reading can be selected within the range of volt or decibel.

Applications of Wave Analyzer

The applications of wave analyzers include the following.

  • It measures the signal’s harmonic distortion.
  • Used in electrical, vibration, and sound measurements
  • The signal energy can be measured using well-defined BW.
  • Amplifier’s harmonic distortion can be measured and also each separate component can be determined in a periodic signal.
  • Wave analyzer is applicable for electrical measurements
  • By using this analyzer, harmonics can be separated as well as displayed
  • It is used as an automatic frequency controller
  • It is used to decrease the sound as well as vibration generated through the machines which are used in electrical industries.
  • Used to measure the amplitude of the preferred frequency component within the signal.
  • It is used as a harmonic distortion analyzer
  • The signals desired frequency components can be chosen to examine the signal
  • It is used for measuring the signal amplitude through the noise as well as interfacing signals
  • It is mainly used for analyzing the DC component within the periodic signal

Thus, this is all about an overview of wave analyzer. This is one kind of instrument mainly used to compute the signal frequency component’s relative amplitude within a waveform. The waveform analysis can be done in the frequency domain using a voltmeter as well as a set of tuned filters. This kind of analyzer is also known as carrier frequency, frequency selective, and selective level voltmeters. This analyzer is adjusted to the frequency of the component whose amplitude needs to measure. Here is a question for you, what are the advantages of a wave analyzer?

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