数字信号处理(T6A)考试试卷.docx

Digital Signal Processing考试试卷(A题)1. Direction: Fill the best answer into the bracket for each of the following sentences.(2’ 20=40’)(1). The z-transform of the unit step sequence μ[n] is ( ).(2). The DTFT of δ[n-2] is ( ).(3). Specify the ROC of to be , then the inverse z-transform of is ( ).(4). The ROC of the z-transform of the sequence x[n] = 0.2nμ[n] + 0.3nμ[-n-1] is ( ).(5). An FIR discrete-time LTI system is always ( ).(6). Let X[k] be the 8-point DFT of an 8-point real sequence x[n], and it is known that X[0] = 12, X[1] = -1 +j3, X[2] = 3 + j4, X[3] = 1 – j5, X[4] = 4, X[5] = 1 + j5, X[7] = -1 – j3, then X[6] = ( ).(7). The linear convolution of g[n] and h[n] is yL[n] = {1, 2, 3, 4, 5, 6}, The 5-point circular convolution of g[n] and h[n] is yC[n] = ( ).(8). A causal LTI discrete-time system is described by the difference equation: , its unit impulse response h[n] = ( ).(9). For an LTI discrete-time system with its frequency response , if the input sequence is x[n] =, the corresponding steady-state response is y[n] = ( ).(10). The DTFT of a sequence x[n] is denoted as , then the DTFT of the time shifted version x[n-1] of x[n] is ( ).(11). We can use three basic operations to construct an arbitary complicated discrete-time LTI system. These three basic operations are addition, ( ) and unit delay.(12). A causal LTI discrete-time system is described by the difference equation , then the transfer function is ( ).(13). The continuous-time signal xa(t) = 3cos(200πt) + 5cos(1200πt) is sampled at a 2000Hz rate generating a discrete-time sequence x[n], then the expression of the discrete-time sequence is x[n] = ( ).(14). The DTFT of a sequence x[n] is denoted as , then the DTFT of is ( ).(15). Suppose that is the DTFT of a real sequence x[n], the magnitude spectrum is an ( ) function of ω.(16). F