Demodulation [What is Demodulation, AM demodulation methods]

What is Demodulation?

The process of separating the original information or signal from the Modulated-carrier signal. When it comes to amplitude or frequency modulation it entails a tool, called a demodulator or detector, which produces a signal corresponding to the instantaneous changes in amplitude or frequency, respectively.

This signal corresponds to the original modulating signal. In radio transmission, this process is a significant feature of a Receiver, in order to obtain the desired signal.

Detection or demodulation

The terms detection and demodulation are frequently utilized when referring to the general demodulation procedure. Basically, the terms describe the same process, and also the same circuits. As the name shows the demodulation procedure is the reverse of modulation, where a signal such as an audio signal is applied to a carrier signal.

AM demodulation methods

There are a variety of techniques that can be utilized to demodulate AM signals. Various types are utilized in different applications to fit their performance as well as expense.

Diode rectifier envelope detector

This form of detector is the most basic kind, only requiring a single diode and a number of various other low-cost parts. The performance suffices for inexpensive AM broadcast radios, yet it does not fulfill the standards of various other forms of demodulation.

Product detector

It is feasible to demodulate amplitude-regulated signals with a receiver that integrates a product detector of the mixer and a local beat frequency oscillator or carrier injecting oscillator. In its fundamental form, the local oscillator is not synchronized to the incoming signal carrier.

Synchronous detection

The synchronous detector or demodulator is effectively a development of the product detector circuit as well as it, therefore, supplies the maximum efficiency for the demodulation of AM signals.

It uses much more parts than a simple diode detector, yet because of the uptake of incorporated circuit modern technology, it is really simple to include this form of demodulator into several radio receivers for nearly zero incremental expense.

FM demodulation techniques

The main types of FM demodulator found in broadcast receivers, radio communication systems two-way radios or walkie talkies/ handheld radios, etc.,

Slope detection

This is a very simple and basic type of FM demodulation and also it relies upon the selectivity of the receiver itself to provide the demodulation. It is not especially reliable and also is not made use of other than when the receiver does not have an FM capability.

Ratio detector

This sort of detector was one that was extensively made use of when discrete parts were utilized in transistor radios. The ratio detector was required for making use of a transformer that had a third winding to generate an added signal which was stage shifted for the demodulation procedure.

The ratio detector utilized two diodes in addition to a couple of resistors and also capacitors.

• These FM demodulators are utilized in different applications. The various types of FM demodulators give designers an option of techniques relying on the application: broadcast, two-way radio communications, high requirements communications receivers, and so on.

MCQs about Demodulation