What we have learnt so far is how to convert an analog signal into a digital signal and to process it using digital filters. The field of digital signal processing has fully matured and has found applications in diverse fields. In this chapter, we will concentrate on the application of DSP in one particular field, namely, the field of digital communications. Radio, telephony, and video are a few of the areas that are completely enveloped by modern digital and wireless communications. Radio broadcast started with analog communications. It used analog modulation techniques such as amplitude modulation (AM) and frequency modulation (FM) to transmit the message signal using radio frequencies (RF). These modulation schemes use the message signal to modulate a carrier signal in its amplitude (AM) or in its instantaneous frequency (FM) before transmission. Later digital modulation methods were introduced to serve the same purpose as the analog counterparts. Digital modulation plays an important role in modern wireless communications. The art of making very large-scale integrated (VLSI) circuits has evolved tremendously. This has enabled the design and fabrication of application-specific integrated circuits (ASIC), which in turn enables the implementation of complex digital techniques in achieving communications successfully as well as lowering the cost. Digital communication systems have many advantages over the analog counterparts. For instance, digital communications has greater immunity to noise. It is also robust to channel impairments. Another advantage is that many different data can be multiplexed and transmitted over a single channel. The various data may include voice, video, and other data, for instance. Since binary digits (bits) are used in digital communications, there is greater security in the transmitted data. This is not feasible in analog communications. Even if there are errors in the received data, they can be detected and corrected by employing what is known as the channel coding, in which extra bits are added to the data bits. In analog communications, the noise in the channel will distort the message signal and is, therefore, impossible to recover the original signal. Even though digital modulation as such occupies a higher bandwidth than analog modulation, source coding or data compression is used to reduce the message bandwidth to start with. Digital communication link performance can be improved by using encryption and channel equalization techniques. Moreover, field programmable gate arrays (FPGA) enable the implementation of digital modulation and demodulation functions purely in software. This has an enormous implication because many handheld devices can perform a variety of functions well in real time using software. These features are certainly a no-no in analog communications.

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  1. 1.
    Ansari R, Liu B (1993) Multirate signal processing. In: Mitra SK, Kaiser JF (eds) Handbook for digital signal processing, Chapter 14. Wiley-Interscience, New York, pp 981–1084zbMATHGoogle Scholar
  2. 2.
    Burns P (2003) Software defined radio. Artech House, BostonGoogle Scholar
  3. 3.
    Couch LW II (1983) Digital and analog communication systems. Macmillan, New YorkGoogle Scholar
  4. 4.
    Crochiere RE, Rabiner LR (1983) Multirate digital signal processing. Prentice Hall, Englewood CliffsGoogle Scholar
  5. 5.
    Fliege NJ (1994) Multirate digital signal processing. Wiley, New YorkzbMATHGoogle Scholar
  6. 6.
    Freking ME (1994/2005) Digital signal processing in communication systems. Van Nostrand Reinhold/Cambridge University Press, New YorkCrossRefGoogle Scholar
  7. 7.
    Gardner FM (1979) Phaselock techniques, 2nd edn. Wiley, New YorkGoogle Scholar
  8. 8.
    Jayant NS, Knoll P (1984) Digital coding of waveforms. Prentice Hall, Englewood CliffsGoogle Scholar
  9. 9.
    Kenington PB (2005) Software defined radio. Artech House, BostonGoogle Scholar
  10. 10.
    Lindsey WC, Simon MK (1977) Detection of digital FSK and PSK using a first-order phase-locked loop. IEEE Trans Commun COM-25(2):200–2014CrossRefGoogle Scholar
  11. 11.
    Lindsey WC, Simon MK (eds) (1977) Phase locked loops and their applications. IEEE Press, New YorkGoogle Scholar
  12. 12.
    Luthra A, Rajan G (1991) Sampling rate conversion of video signals. SMPTE J 100:869–879CrossRefGoogle Scholar
  13. 13.
    Mitra SK (2011) Digital signal processing: a computer-based approach, 4th edn. McGraw-Hill, New York, NYGoogle Scholar
  14. 14.
    Papoulis A (1965) Probability, random variables, and stochastic processes. McGraw-Hill, New YorkzbMATHGoogle Scholar
  15. 15.
    Pickholtz RL, Schilling DL, Milstein LB (1982) Theory of spread-spectrum communications – a tutorial. IEEE Trans Commun COM30(5):855–884CrossRefGoogle Scholar
  16. 16.
    Proakis JG (1983) Digital communications. McGraw-Hill, New YorkzbMATHGoogle Scholar
  17. 17.
    Rappaport TS (2002) Wireless communications: principles and practice, 2nd edn. Prentice Hall, Upper Saddle RiverzbMATHGoogle Scholar
  18. 18.
    Reed JH (2002) Software radio – a modern approach to radio engineering. Prentice Hall, Upper Saddle RiverGoogle Scholar
  19. 19.
    Schilling RJ, Harris SL (2012) Digital signal processing using MATLAB, 3rd edn. Cengage Learning, BostonGoogle Scholar
  20. 20.
    Scholtz RA (1982) The origins of spread spectrum communications. IEEE Trans Commun COM30(5):822–854CrossRefGoogle Scholar
  21. 21.
    Sklar B (1988) Digital communications: fundamentals and applications. Prentice Hall, Englewood CliffszbMATHGoogle Scholar
  22. 22.
    Viterbi AJ (1966) Principles of coherent communications. McGraw-Hill, New YorkGoogle Scholar
  23. 23.
    Viterbi AJ (1995) CDMA: principles of spread spectrum communication, Addison-Wesley Wireless Communications Series. Addison-Wesley Publisher, ReadingzbMATHGoogle Scholar

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© Springer International Publishing AG, part of Springer Nature 2019

Authors and Affiliations

  • K. S. Thyagarajan
    • 1
  1. 1.Extension ProgramUniversity of California, San DiegoSan DiegoUSA

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