[工学]英文版《信号与系统》第678章讲义

1,Chapter 6Time and Frequency Characterizationof Signals and Systems,2,Time-Domain:,Frequency-Domain:,6.1 The Magnitude-Phase Representation （ 幅度-相位） of the Fourier Transform,Magnitude,Energy-Density,3,6.2 The Magnitude-Phase Representation of the Frequency Response of LTI Systems,Gain,Phase Shift,4,6.2.1 Linear and Nonlinear Phase,1. Linear Phase,5,2. Nonlinear Phase,6,Homework: 6.5 6.23,7,6.5 Consider a continuous-time ideal bandbass filter whose frequency response is,If is the impulse response of this filter, determine a function such that,(b) As is increased, does the impulse response of the filterget more concentrated or less concentrated about the origin?,Solution,(b) It will get more concentrated about the origin.,(a),8,(b) , where T is a constant.,9,(c),10,Chapter 7 Sampling,11,12,7.1 The Sampling Theorem,7.1.1 Impulse-Train Sampling,13,14,When aliasing occurs,Homework: 7.1 7.2 7.3 7.6 7.9,7.3 The Effect of Undersampling: Aliasing 欠采样 混叠,15,7.1 A real-valued signal is known to be uniquely determined by its samples when the sampling frequency is . For what values of is guaranteed to be zero?,16,7.2 A continuous-time signal is obtained at the output of an ideal lowpass filter with cutoff frequency . If impulse-train sampling is performed on ,which of the following sampling periods would guarantee that can be recovered from its sampled version using an appropriate lowpass filter? (a) T=0.510-3 (b) T=210-3 (c) T=10-4,(a) and (c),Sampling interval,17,7.3 Determine the Nyquist rate corresponding to each of the following signals:,18,Nyquist rate,maximum sampling interval,19,20,Chapter 8 Communication Systems,21,ModulatingSignal,Carrier Signal,ModulatedSignal,22,8.1 Complex Exponential and Sinusoidal Amplitude Modulation,8.1.1 Amplitude Modulation with a Complex Exponential Carrier,carrier frequency,initial phase,Modulation :,Demodulation :,23,8.1.2 Amplitude Modulation with a Sinusoidal Carrier,Modulation :,24,25,8.2.1 Synchronous Demodulation,26,Suppose the modulator and demodulator are not synchronized in phase.,Transmitter Carrier, Complex Exponential Carrier,ReceiverCarrier,When ,27, Sinusoidal Carrier,Transmitter Carrier,ReceiverCarrier,The output of LPF is:,28,2. Suppose the modulator and demodulator are not synchronized in frequency.,Transmitter Carrier,ReceiverCarrier,The output of LPF is:,29,30,8.3 Frequency-Division Multiplexing（频分复用）,31,32,Homework: 8.1 8.3 8.22,33,34,Solution,35,8.22In Figure (a) ,a system is shown with input and outputThe input signal has the Fourier transform shown in Figure (b)Determine and sketch .,Figure (a),Figure (b),36,37,38,If is real ,even,39,2. If is real ,odd,40,Solution :,41,2.,3.,42,Example 5 In Figure (a), a system is shown with input signal and output signal . If the following information are given.,1. Determine,2. Determine the impulse respons