Why is modulation needed

Need of Modulation You may ask, when the baseband signal can be transmitted directly why to use the modulation? The answer is that the baseband transmission has many limitations which can be overcome using modulation.

It is explained below. Avoids mixing of signals 3. Improves quality of reception Modulation is a process in which the feature amplitude, phase or frequency of the carrier signal is changed in accordance with instantaneous value of modulating signal. Modulation is needed for many reasons. In a carrier communication system, the baseband signal of a low-frequency spectrum is translated to a high frequency spectrum.

This is achieved through modulation. The aim of this topic is to explore the reasons for using modulation. Modulation is defined as a process by virtue of which, some characteristic of a high frequency sinusoidal wave is varied in accordance with the instantaneous amplitude of the baseband signal. Two signals are involved in the modulation process. The baseband signal and the carrier signal. The baseband signal is to be transmitted to the receiver.

The frequency of this signal is generally low. In the modulation process, this baseband signal is called the modulating signal. The waveform of this signal is unpredictable. For example, the waveform of a speech signal is random in nature and cannot be predicted. In this case, the speech signal is the modulating signal. The other signal involved with the modulation is a high frequency sinusoidal wave.

This signal is called the carrier signal or carrier. The frequency of the carrier signal is always much higher than that of the baseband signal. After modulation, the baseband signal of low frequency is transferred to the high frequency carrier, which carries the information in the form of some variations.

After the completion of the modulation process, some characteristic of the carrier is varied such that the resultant variations carry the information.

In principle, these parameters have constant values for a particular sinusoidal wave. According to the definition of Modulation, some characteristic of the carrier signal is varied in accordance with the modulating signal. After modulation any one of the three parameters of the carrier signal, namely, frequency, or phase, is varied keeping the remaining two constant. The baseband signal is then carried by these variations. The type of the modulation is decided by the parameter chosen to vary.

For example, if amplitude of the carrier is chosen to vary in accordance with the instantaneous amplitude of the baseband signal, keeping frequency and phase constant, the resulting.

Frequency modulation and phase modulation are also obtained in a similar way. Low-frequency baseband sign it is thus translated to a high frequency carrier such that the information is coded in the variations in one of the parameters of the carrier. At the receiver side, these variations are detected through the demodulation process to recover the original baseband signal.

The following can be summarized with reference to modulation. During the modulation process, the modulating, signal varies the frequency, y, amplitude, or phase of the carrier in accordance with its instantaneous amplitude. The process of modulation in a communication system increases its cost and complexity. This may be considered as a disadvantage. However, modulation is extensively used in most communication systems. There is a definite need for using modulation.

There can be problems if modulation is not used. Scrutinizing these problems can explain why modulation is required. The baseband signal will be transmitted as it is. We are the leading communication supplier in manufacturing the headend system in China. Our 16 in 1 and 24 in 1 now are the most popular products all over the world. Read Now. Recommended Articles. Article Contributed By :.

Easy Normal Medium Hard Expert. Writing code in comment? Please use ide. Load Comments. What's New. All 3 parameters can be altered to transmit data. The sinusoidal signal that is used in the modulation is known as the carrier signal , or simply "the carrier".

The signal that is used in modulating the carrier signal or sinusoidal signal is known as the "data signal" or the "message signal". It is important to notice that a simple sinusoidal carrier contains no information of its own. In other words we can say that modulation is used because some data signals are not always suitable for direct transmission, but the modulated signal may be more suitable. There are 3 basic types of modulation: Amplitude modulation, Frequency modulation, and Phase modulation.

Why use modulation at all? To answer this question, let's consider a channel that essentially acts like a bandpass filter: both the lowest frequency components and the highest frequency components are attenuated or unusable in some way, with transmission only being practical over some intermediate frequency range. If we can't send low-frequency signals, then we need to shift our signal up the frequency ladder.

Modulation allows us to send a signal over a bandpass frequency range. If every signal gets its own frequency range, then we can transmit multiple signals simultaneously over a single channel, all using different frequency ranges. Another reason to modulate a signal is to allow the use of a smaller antenna.