modulation is process of changing

Description: Modulation is the process of altering certain characteristics (such as amplitude, frequency, or phase) of a carrier wave in accordance with the intensity of the signal. The provided figure illustrates the electronic circuit of a simple amplitude modulation (AM) modulator. This circuit primarily consists of a common emitter (CE) amplifier with a voltage gain denoted as A. The carrier signal is fed into the amplifier's input, while the modulating signal is introduced in the emitter resistor circuit. The amplifier enhances the carrier signal by a factor of A, resulting in an output of A times the modulating signal. As the modulating signal is integrated into the biasing circuit, it generates low-frequency variations within the emitter circuit, leading to fluctuations in the voltage gain A. Consequently, the amplitude of the carrier signal varies according to the strength of the modulating signal, producing an amplitude-modulated output across the load resistor (RL). It is essential to ensure that the carrier does not affect the voltage gain A; instead, only the modulating signal should exert this influence. To accomplish this, the carrier signal should possess a small magnitude, while the modulating signal should have a significantly larger magnitude.

The described AM modulator circuit operates on the principle of amplitude modulation by utilizing a common emitter amplifier configuration. In this setup, the carrier wave, typically a high-frequency signal, is introduced at the amplifier's input. The amplifier is biased to operate in the active region, ensuring linear amplification of the signals.

The modulating signal, which contains the information to be transmitted, is applied to the emitter resistor. This configuration allows the modulating signal to influence the emitter current, thereby affecting the collector current and the output voltage across the load resistor. The voltage gain A of the amplifier is determined by the ratio of the collector resistor to the emitter resistor, as well as the transistor's characteristics. The output voltage across RL will be the amplified version of the modulating signal superimposed on the carrier wave.

It is crucial to maintain the amplitude of the carrier wave at a lower level compared to the modulating signal to prevent distortion and ensure that the modulating signal can effectively vary the amplitude of the carrier without altering its frequency or phase. The design should also consider the frequency response of the circuit, ensuring that it can adequately handle the frequency range of the modulating signal while maintaining the integrity of the carrier wave.

In summary, the AM modulator circuit serves as a fundamental building block in communication systems, enabling the transmission of information over long distances by modulating the amplitude of a carrier wave in accordance with the variations in the modulating signal. Proper design and implementation of this circuit are essential for achieving high-quality amplitude modulation with minimal distortion.Modulation is the process of changing some characteristics (e. g. amplitude, frequency or phase) of a carrier wave in accordance with the intensity of the signal is known as modulation. The figure shows the electronics circuit of a simple am modulator. It is essentially a CE amplifier having a voltage gain of A. The carrier signal is the input tothe amplifier. The modulating signal is applied in the emitter resistance circuit. The carrier ec is applied at the input of the amplifier and the modulating signal es is applied in the emitter resistance circuit. The amplifier circuit amplifies the carrier by a factor A, so that the output is Aes. Since the modulating signal is a part of the biasing circuit, it products low frequency variations in the emitter circuit.

This in turn causes variations in A . The result is that amplitude of the carrier varies in accordance with the strength of the signal. Consequently, amplitude modulated output is obtained across RL. It may be noted that carrier should not influence the voltage gain A; only the modulating signal should do this. To achieve this objective, carries should have a small magnitude and signal should have a large magnitude.