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Difference between Modulation and Demodulation
There are two important processes used in data communication namely, modulation and demodulation. Both these processes make a communication successful by the transfer of data and information with the minimum distortion, minimum losses and efficient use of spectrum. The electronic device that is employed to perform modulation and demodulation is called modem. It performs modulation and demodulation of information during its transmission.
In this article, we will discuss the major differences between modulation and demodulation by considering various factors such as basic definition, purpose, implementation, need, etc. But before going into the differentiation part, it is beneficial to gather basic information about the modulation and demodulation so that the understanding of differences becomes easy.
What is Modulation?
The process of superimposing a message signal on a carrier signal so that the message can be transmitted over long distances is called modulation. Here, the carrier signal is the signal of high frequency which is used to carry the message signal. The following figure shows the block diagram of modulation.
The modulation of a signal is performed at the transmitting end in the communication system with the help of a modulator circuit (a part of modem). In the modulation, a specific parameter, i.e. amplitude, frequency or phase, of the carrier signal is altered in accordance with the modulating signal or message signal. After modulation, the modulated signal is transmitted over the communication channel by a transmitter.
The common types of modulation that are being extensively used in data communication are − amplitude modulation, frequency modulation, phase modulation, polarization modulation, pulse code modulation, quadrature amplitude modulation, etc.
The modulation process is widely used in transmission of signals using electromagnetic waves, radio waves, optics (in fiber optics), etc.
What is Demodulation?
The process of obtaining the original message from the modulated signal is called demodulation. In simple words, demodulation is the process of separating a message signal from a carrier signal. The process of demodulation is shown in the following block diagram.
The electronic circuit that is used to perform the demodulation process is called demodulator, it is the part of the modem. The process of demodulation is performed at the receiver end of a communication system.
Difference between Modulation and Demodulation
Modulation and demodulation are the basic processes involved in data communication. There are many differences between modulation and demodulation that are highlighted in the following table −
| Basis of Difference | Modulation | Demodulation |
|---|---|---|
| Definition | The process of superimposing a low energy message signal on a high energy carrier signal is known as “modulation”. | The process of extracting the message signal from a modulated signal is known as “demodulation”. |
| Operation end | The process of modulation is performed at transmission end of the communication system. | Demodulation is performed at receiving end of the communication system. |
| Circuit required | The electronic circuit that is required to perform modulation is called modulator. | The electronic circuit required to done demodulation is called demodulator or sometimes, detector. |
| Process | In modulation, the message signal is added on a carrier wave for transmission. | In demodulation, the message is separated from the carrier signal. |
| Need | Modulation process is need for mixing of two signal of different parameters together. | Demodulation is needed for recovery of original signal from a mix of two signals. |
| Purpose | The main purpose of modulation is to transmit the messages to long distances. | The purpose of demodulation is to regain the original message at the receiver end. |
| Process complexity | The process of modulation is comparatively simple. | The demodulation involves relatively more complex process for the recovery of data. |
| Signal transformation | In modulation, the parameter of the signal (such as frequency, amplitude, phase, etc.) is transformed from low to high value. | In demodulation, the signal parameter is transformed from high to low value. |
Conclusion
Both modulation and demodulation are important processes in data communication. Both modulation and demodulation can be performed by a same device called modem (modulator-demodulator). There are many differences between modulation and demodulation that are listed in the above table. The most significant difference is that in modulation, the message signal is mixed with the carrier signal; while in demodulation, the message signal is separated from the carrier signal.
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