Introduction to Modulation and Demodulation

Introduction to Modulation and Demodulation - EEE2009...

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EEE2009 EEE2009 Communications Communications Contents Introduction to Communication Systems Analogue Modulation AM, DSBSC, VSB, SSB, FM, PM, Narrow band FM, PLL Demodulators, and FLL Loops Sampling Systems Time and Frequency Division multiplexing systems, Nyquist Principle, PAM, PPM, and PWM. Principles of Noise Random variables, White Noise, Shot, Thermal and Flicker Noise, Noise in cascade amplifiers Pulse Code Modulation PCM and its derivatives, Quantising Noise, and Examples Digital Communication Techniques ASK, FSK, PSK, QPSK, QAM, and M-ary QAM. Case Studies Spread Spectrum Systems, Mobile radio concepts, GSM and Multiple Access Schemes Mobile radio
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Recommended Text Books Recommended Text Books “An introduction to Analogue and Digital communication”, Haykin (Wiley) “Information, Transmission, Modulation and Noise”, Schwartz “Analogue and Digital Communication Systems”, Raden (Prentice- Hall) “Communication Systems”, Haykin (Wiley) “Electronic Communication Techniques”, Young (Merril-Publ)
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Introduction to Modulation and Introduction to Modulation and Demodulation Demodulation The purpose of a communication system is to transfer information from a source to a destination. n practice, problems arise in baseband transmissions, he major cases being: Noise in the system – external noise and circuit noise reduces the signal-to-noise (S/N) ratio at the receiver (Rx) input and hence reduces the quality of the output. Such a system is not able to fully utilise the available bandwidth, for example telephone quality speech has a bandwidth 3kHz, a co-axial cable has a bandwidth of 100's of Mhz. Radio systems operating at baseband frequencies are very difficult. Not easy to network.
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Multiplexing Multiplexing Multiplexing is a modulation method which improves channel bandwidth utilisation. For example, a co-axial cable has a bandwidth of 100's of Mhz. Baseband speech is a o
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1) Frequency Division Multiplexing FDM 1) Frequency Division Multiplexing FDM This allows several 'messages' to be translated from baseband, where they are all in the same frequency band, to adjacent but non overlapping parts of the spectrum. An example of FDM is broadcast radio (long wave LW, medium wave MW, etc. )
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2) Time Division Multiplexing TDM 2) Time Division Multiplexing TDM TDM is another form of multiplexing based on sampling which is a modulation technique. In TDM, samples of several analogue message symbols, each one sampled in turn, are transmitted in a sequence, i.e. the samples occupy adjacent time slots.
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Radio Transmission Radio Transmission Aerial dimensions are of the same order as the wavelength, λ , of the signal ( e.g. quarter wave λ /4, λ /2 dipoles). λ
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This note was uploaded on 01/20/2012 for the course EE 301 taught by Professor Ahmetçakar during the Spring '11 term at Gazi Üniversitesi.

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Introduction to Modulation and Demodulation - EEE2009...

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