PPT-Chapter 2 … Modulation

Techniques 24 marks Visit for more Learning Resources Transmission Techniques Baseband Transmission The electrical equivalent of original information is known as the baseband signal . The reason for that may be that the channel is bandlimited or that we are assigned a certain frequency band and frequencies outside that band is supposed to be used by others Therefore we are interested in the spectral properties of v arious modulat Husheng Li. The University of Tennessee. Chopper Sampling . We introduce a switching function such that . x_s. (t)=x(t)s(t), where. Nyquist. Criterion. The sampling rate should be at least twice the bandwidth of the signal, in order to fully reconstruct the signal.. Husheng Li. The University of Tennessee. Phase and Frequency Modulation. Consider the standard CW signal. We define the total instantaneous angle. Phase and Frequency Modulation. Phase modulation (PM). Husheng Li. The University of Tennessee. AM Signals and Spectra. An AM signal can be written as. Power of AM. The total transmit power is given by. We can prove that, at least 50% (often close to 2/3) of the total transmitted power resides in a carrier term that is independent of the signal and thus conveys no message information. (what a waste!). Husheng Li. The University of Tennessee. Course Contents. Basics of communications. Signals and noise. Amplitude modulation. Phase and frequency modulations. Pulse modulation. Analog communication system. Husheng Li. The University of Tennessee. Phase and Frequency Modulation. Consider the standard CW signal. We define the total instantaneous angle. Phase and Frequency Modulation. Phase modulation (PM). Husheng Li. The University of Tennessee. Chopper Sampling . We introduce a switching function such that . x_s. (t)=x(t)s(t), where. Nyquist. Criterion. The sampling rate should be at least twice the bandwidth of the signal, in order to fully reconstruct the signal.. Husheng Li. The University of Tennessee. AM Signals and Spectra. An AM signal can be written as. Power of AM. The total transmit power is given by. We can prove that, at least 50% (often close to 2/3) of the total transmitted power resides in a carrier term that is independent of the signal and thus conveys no message information. (what a waste!). Amplitude Modulation (AM). Time domain equation. y. AM. (t. ) = . Information or message x carrier. . = . m(t) . x A cos(w. c. t. ). . Frequency domain equation. Double . sideband . Prof. Park. NJIT. Problem 1. Which . of the following is NOT produced when two sine waves are . combined through . a nonlinear device?. a. . Components of each of the two original frequencies. b. . Components at the sum and difference frequencies. What Will we Learn from chapter 8?. Physical . layer protocols and services in supporting communication across data . networks. The role . of signals used to represent bits as a frame . transported . Binary modulation schemes . ASK. , FSK, . PSK. n. = . 1, . M = 2 (Only Two . output conditions are . possible). Baud . is equal to . the bit . rate. M-. ary. Modulation Techniques. QPSK, 8-PSK, 18-PSK, QAM, 16-QAM. First and second generation communication systems . divide. the total available bandwidth into smaller bandwidth channels . However, third generation systems . share. the entire bandwidth without mutual interference. Prof. Brian L. Evans. Dept. of Electrical and Computer Engineering. The University of Texas at Austin. 15 - . 2. Introduction. Digital Pulse Amplitude Modulation (PAM). Modulates digital information (symbols) onto amplitude of pulse.