Academia.eduAcademia.edu

Figure 2 – uploaded by Er Harpreet Kaur Channi

See full PDFdownloadDownload figure
An analysis of the digital modulation technique carried out in this article reveals that the selection of a digital modulation technique is solely dependent on the type of application. This is because of the fact that some of the technique provide lesser

Table 2 An analysis of the digital modulation technique carried out in this article reveals that the selection of a digital modulation technique is solely dependent on the type of application. This is because of the fact that some of the technique provide lesser

Related Figures (3)

signals are transmitted via digital modulation and demodulated as a digital signal at the receiver. Figure 1 illustrates the basic elements of a digital communication system [1]. The source output may be either an analog signal, such as an audio or video signal, or a digital signal, such as the output of a teletype machine, that is discrete in time and has a finite number of output characters. In a digital communication system, the messages produced by the source are converted into a sequence of binary digits. The process of efficiently converting the output of either an analog or digital source into a sequence of binary digits is called source encoding or data compression. The sequence of binary digits called information from the source encoder is passed to the channel encoder. The purpose of the channel encoder is to introduce, in a controlled manner, some redundancy in the binary information sequence that can be used at the receiver to overcome the effects of noise and interference encountered in the transmission of the signal through the channel. This increases the reliability of the received data and improves the fidelity of the received signal [2]. The binary sequence at the output of the channel encoder is passed to the digital modulator, which serves as the interface to the communication channel. The modulation process begins with the data to be transmitted being fed to a DSP device that generates two digital outputs, which are needed to define the amplitude and phase information required at the receiver to recover the data. The DSP produces two baseband streams that Department of Electrical and. Electronics Engineering Chandigarh University, Gharuan, Mohali, Punjab, India.
signals are transmitted via digital modulation and demodulated as a digital signal at the receiver. Figure 1 illustrates the basic elements of a digital communication system [1]. The source output may be either an analog signal, such as an audio or video signal, or a digital signal, such as the output of a teletype machine, that is discrete in time and has a finite number of output characters. In a digital communication system, the messages produced by the source are converted into a sequence of binary digits. The process of efficiently converting the output of either an analog or digital source into a sequence of binary digits is called source encoding or data compression. The sequence of binary digits called information from the source encoder is passed to the channel encoder. The purpose of the channel encoder is to introduce, in a controlled manner, some redundancy in the binary information sequence that can be used at the receiver to overcome the effects of noise and interference encountered in the transmission of the signal through the channel. This increases the reliability of the received data and improves the fidelity of the received signal [2]. The binary sequence at the output of the channel encoder is passed to the digital modulator, which serves as the interface to the communication channel. The modulation process begins with the data to be transmitted being fed to a DSP device that generates two digital outputs, which are needed to define the amplitude and phase information required at the receiver to recover the data. The DSP produces two baseband streams that Department of Electrical and. Electronics Engineering Chandigarh University, Gharuan, Mohali, Punjab, India.
Fig 2: ASK, FSK, PSK Modulation is the process of varying some parameter of a periodic waveform in order to use that signal to convey a message. Normally a high-frequency sinusoidal waveform is used as carrier signal. For this purpose, if the variation in the parameter of the carrier is continuous in accordance to the input analog signal the modulation technique is termed as analog modulation scheme and if the variation is discrete then it is termed as Digital Modulation Technique [11]. Figure 2 shows the modulation of data using basic modulation techniques. Digital modulation techniques may be classified into coherent and non-coherent techniques, depending upon whether the receiver is equipped with a phase recovery circuit or not. These digital modulation techniques can also be classified basically either on the basis of their detection characteristics or in terms of their bandwidth compaction characteristics [12]. After the
Fig 2: ASK, FSK, PSK Modulation is the process of varying some parameter of a periodic waveform in order to use that signal to convey a message. Normally a high-frequency sinusoidal waveform is used as carrier signal. For this purpose, if the variation in the parameter of the carrier is continuous in accordance to the input analog signal the modulation technique is termed as analog modulation scheme and if the variation is discrete then it is termed as Digital Modulation Technique [11]. Figure 2 shows the modulation of data using basic modulation techniques. Digital modulation techniques may be classified into coherent and non-coherent techniques, depending upon whether the receiver is equipped with a phase recovery circuit or not. These digital modulation techniques can also be classified basically either on the basis of their detection characteristics or in terms of their bandwidth compaction characteristics [12]. After the
The basic research work carried out in the field of communication lead to the development of new modulation techniques, coding techniques, error rate performances analysis but the ever increasing demand of the faster communication system with large bandwidth requirements has again generated a new hunger towards the development of newer techniques, so many modulation techniques like BPSK, DPSK, MSK, GMSK, M-ary QAM have been developed. Table 1gives the spectral efficiency of various digital modulation schemes. Table 2 shows the comparison of modulation schemes on the basis of their merits and demerits.
The basic research work carried out in the field of communication lead to the development of new modulation techniques, coding techniques, error rate performances analysis but the ever increasing demand of the faster communication system with large bandwidth requirements has again generated a new hunger towards the development of newer techniques, so many modulation techniques like BPSK, DPSK, MSK, GMSK, M-ary QAM have been developed. Table 1gives the spectral efficiency of various digital modulation schemes. Table 2 shows the comparison of modulation schemes on the basis of their merits and demerits.
Related topics:
Spectral Efficiency
580 California St., Suite 400
San Francisco, CA, 94104
© 2025 Academia. All rights reserved