第三章单元测试
- There is a one-to-one correspondence between a discrete time signal
and its Fourier transform
.（ ） - The spectrum of a sequence can be graphed by magnitude frequency characteristics and phase frequency characteristics.（ ）
- The DTFT
of a sequency 
is a periodic and discrete function of 
.（ ） - If
，then 
.（ ） - The below figure is one of the ways to compute the linear convolution of x (n) and h (n). Which Fourier transform property does it follow? （ ）
- For the following sequence types, whose Fourier transform is conjugate-symmetric? （ ）
- If the DTFT of a sequency is expressed as
，then
is referred to as （ ）. - As for understanding on the development and role of Fourier transform，which are correct for the following statements？ （ ）
- For a sequence with a period of N, its DFS is not necessarily a sequence with a period of N.（ ）
- The Z-transform
together with its ROC determines a sequence 
uniquely.（ ） - As for understanding on the physical meaning of frequency response，which are correct for the following statements？（ ）
- For the transfer function
of a causal and stable system, which are correct for the following statements？（ ）
A:对 B:错
答案:对
A:错 B:对
A:错 B:对
A:错 B:对
A:Frequency-Domain Convolution Theorem B:Time-Domain Convolution Theorem C:Frequency Shifting Theorem D:Time Shifting Theorem
A:an imaginary-valued sequence B:a conjugate-symmetric sequence C:a complex-valued sequence D:a real-valued sequence
A:harmonic component B:energy C:fundamental component D:direct current component
A:FT realizes the conversion of signals from time domain to frequency domain theoretically. B:DFT provides a method of approximate estimation of signal spectrum by digitization. C:FFT improves the efficiency of DFT and meet the needs of real-time processing in engineering practice. D:All other options are correct.
A:对 B:错
A:对 B:错
A:The magnitude response shows that how the system affects amplitude attenuation of each frequency component in the input signal. B:For a complex exponential input signal with single frequency, the output of an LTI system is a complex exponential signal of the different frequency. C:The phase response shows that how the system affects time delay of each frequency component in the input signal. D:For a complex exponential input signal with single frequency, the output of an LTI system is also a complex exponential signal of the same frequency.
A:The closer the pole location approaches to the unit circle, the greater the value of magnitude frequency response of the system will be. B:The closer the pole location approaches to the unit circle, the smaller the value of magnitude frequency response of the system will be. C:If the pole is located on the unit circle, then the value of magnitude frequency response of the system is equal to infinity. D:If the pole is located on the unit circle, then the value of magnitude frequency response of the system is equal to zero.
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