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《数字信号处理基础》候正信.pdf

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sol1.pdf
Chapter 1 Solutions
sol2.pdf
Chapter 2 Solutions
Chapter 3 Solutions.pdf
Chapter 3 Solutions
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Chapter 4 Solutions
sol5.pdf
Chapter 5 Solutions
sol6.pdf
Chapter 6 Solutions
sol7.pdf
Chapter 7 Solutions
sol8.pdf
Chapter 8 Solutions
sol9.pdf
Chapter 9 Solutions
sol10.pdf
Chapter 10 Solutions
Defined at every point in time, and at all possible amplitudes. Defined only at certain points in time, and only at certain amplitudes. less dependent on component tolerances less affected by noise Chapter 1 Solutions 1.1 Analog: Digital: lower power consumption 1.2 more predictable behavior smaller in size easier to redesign 1.3 (a) (b) (c) (d) (e) (f) (g) 1.4 sound light temperature light acceleration light temperature Amplitude 1.5 1.6 0 5 10 15 20 25 30 35 40 Time (msec) Output 80.7 μsec increase the number of quantization bits increase the sampling rate 课后答案网 www.khdaw.com
The output analog signal will differ from the input signal as a result of: 1.7 aliasing, if the maximum frequency in the input signal exceeds half of the sampling rate because the anti-aliasing filter is non-ideal time shift, caused by the anti-aliasing and anti-imaging filters quantization, since the number of bits used by the converter is finite 1.8 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 t 5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 0 B x(t) 1.9 1.10 (a) (b) (c) 1.11 (b) 0 5 10 15 f (kHz) The required filter is low pass. The cut-off frequency for the filter should be about 10 kHz. (a) Magnitude A narrowband stop filter would be best to remove the 60 Hz noise. 60 Frequency (Hz) 课后答案网 www.khdaw.com
A low pass filter with a cut-off frequency of about 1 kHz (a) A high pass filter with a cut-off frequency of about 1 kHz (a) Choir Low Pass Band Pass Bass and Alto 1.12 (b) 1.13 (b) Output = (HP) Input + (BP) Input – (HP)(BP) Input = (HP)(1 – BP) Input + (BP) Input The filters may be connected as shown below: Band Pass Choir + Alto or Soprano − + High Pass + 1.14 A filter with sharp, equally-spaced peaks placed at each of the harmonic frequencies of middle C would extract the correct information. Such a filter is called a comb filter. 1.15 Q will be more likely to use a high pass filter, to emphasize the edges and details in the photograph. 课后答案网 www.khdaw.com
The Nyquist rate for the signal is 6.37 Hz (a) The Nyquist rate is 1666.7 Hz. The Nyquist rate is 428.6 Hz. 1 f S = 1 8000 = 125 μs 44.1 kHz. Chapter 2 Solutions 2.1 2.2 (b) (c) 2.3 (a) T S = 4000 kHz. 40. (b) 2.4 9 2.5 2.6 Magnitude 2.7 (a) 1 0 . 9 0 . 8 0 . 7 0 . 6 0 . 5 0 . 4 0 . 3 0 . 2 0 . 1 0 - 2 0 0 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 Frequency The sampling rate meets Nyquist requirements, so no aliasing occurs. 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 Frequency, kHz (b) 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 Frequency, kHz 课后答案网 www.khdaw.com
899970 900000 900030 f (kHz) , − … 300 300 , 600 , 60 kH 1000 ± (a) 300 600 , 0 ± , 2000 ± 600 , 1000 ± 300 , 0 ± − 1000 ± , 1000 ± 1300 , 1000 ± 1300 0 ± 1300 , …, or –2300, –1300, –300, 300, 700, 1300, 2300, 3300 Hz, etc. Only the Copies of the signal at 300 Hz appear at …, Hz, …. These translate to copies at –1300, –700, 300, 700, Copies of the signal appear at …, 600 Copies of the signal appear at …, 1300 2.8 0 30 60 90 120 2.9 1000 ± 1300, 1700, 2300 Hz and so on. Only one of these lies in the Nyquist range (the range recovered after sampling, between 0 and 500 Hz in this case), 300 Hz, the true signal frequency. No aliasing occurs in this case. (b) − 2000 ± , …, or –1600, –600, –400, 400, 600, 1400, 1600, 2600 Hz, etc. The only frequency on this list that falls within the Nyquist range is 400 Hz. This is the aliased frequency. (c) 2000 ± 300 Hz signal lies in the Nyquist range. This is the aliased frequency. 2.10 (a) 2.11 Magnitude (b) Magnitude 2.11 2.12 1000 Hz. This is the aliased frequency. Frequency Frequency 0 . 8 0 . 6 0 . 4 0 . 2 0 . 8 0 . 6 0 . 4 0 . 2 - 0 . 4 - 0 . 6 - 0 . 2 - 0 . 4 - 0 . 6 - 0 . 8 - 1 - 5 0 0 - 1 - 5 0 0 1 0 0 0 fS 1 0 0 0 fS - 0 . 2 - 0 . 8 0 5 0 0 0 5 0 0 1 0 1 0 1 5 0 0 1 5 0 0 n t = nTS x1(t) x2(t) 课后答案网 www.khdaw.com
1.000 –0.809 0.309 0.309 –0.809 1.000 –0.809 1.000 –0.809 0.309 0.309 –0.809 1.000 –0.809 0 1/150 2/150 3/150 4/150 5/150 6/150 28 = 256 900.2 MHz. 6 V. 375 mV 23.44 mV 91.55 μV 2.13 2.14 This can be accomplished by taking 418 snapshots in every 100 seconds. 2.15 750 Hz. 2.16 (a) (b) (c) 2.17 2.18 Quantization maps an infinite number of analog signal levels to a finite number of digital signal levels, determined by the number of bits used. For any finite number of bits, non-zero errors must occur because the quantization step size is non-zero. 2.19 The quantization errors are calculated by subtracting the true signal value from the quantized value. n Quantization Error 2.20 Quantization Step = Range/2N = 4/24 = 0.25 V 0 –0.4 212 = 4096 2 –0.1 (b) 210 = 1024 (c) 4 –0.3 8 –0.2 9 –0.2 3 0.4 5 –0.1 6 0.4 7 –0.1 1 0.3 Digital Code Quantized Level Range of Analog Input Mapping to this Digital Code 0 1 2 3 4 5 6 (a) 0000 0001 0010 0011 0100 0101 0110 0111 1000 (V) –2.0 –1.75 –1.5 –1.25 –1.0 –0.75 –0.5 –0.25 0 (V) –2.0 ≤ x < –1.875 –1.875 ≤ x < –1.625 –1.625 ≤ x < –1.375 –1.375 ≤ x < –1.125 –1.125 ≤ x < –0.875 –0.875 ≤ x < –0.625 –0.625 ≤ x < –0.375 –0.375 ≤ x < –0.125 –0.125 ≤ x < 0.125 课后答案网 www.khdaw.com
1001 1010 1011 1100 1101 1110 1111 0.25 0.5 0.75 1.0 1.25 1.5 1.75 0.125 ≤ x < 0.375 0.375 ≤ x < 0.625 0.625 ≤ x < 0.875 0.875 ≤ x < 1.125 1.125 ≤ x < 1.375 1.375 ≤ x < 1.625 1.625 ≤ x < 2.0 Digital Code Quantized Value 0111 0110 0101 0100 0011 0010 0001 0000 1111 1110 1101 1100 1011 1010 1001 1000 2 1.5 1 0.5 0 -0.5 -1 -1.5 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 Analog Sample Value 2.21 n Digital Code 001 111 001 110 110 010 100 011 100 101 Quantized Level (V) 0.625 4.375 0.625 3.750 3.750 1.250 2.500 1.875 2.500 3.125 Quantization Error (V) 0.0535 –0.5825 0.0000 0.1375 –0.3000 0.2945 –0.2825 0.3125 –0.25 0.2495 Analog Sample (V) 0.5715 4.9575 0.625 3.6125 4.0500 0.9555 2.7825 1.5625 2.7500 2.8755 0 1 2 3 4 5 6 7 8 9 2.22 Dynamic Range = 20 log (2N) (a) (b) (c) 24.1 dB 48.2 dB 96.3 dB 课后答案网 www.khdaw.com
2.23 N = 10. 2.24 N = 3 2.25 2.26 2.27 The table shows the proportional voltages that result for each 3-bit code. 128 kbps 96 kbps. Digital Code Proportional Analog Voltage 000 001 010 011 100 101 110 111 0.0000 0.7143 1.4286 2.1429 2.8571 3.5714 4.2857 5.0000 4.5 3.5 5 4 Voltage The zero order hold signal for the code 111 101 011 101 000 001 011 010 100 110 is shown. 2.28 An anti-imaging filter removes the sharp transitions from the zero order hold signal. In doing so, all frequencies outside of the Nyquist range are eliminated. An incidental time delay is caused by the filter. 450 500 Time 150 0 0 300 350 200 3 2 1 50 100 2.5 1.5 250 400 0.5 课后答案网 www.khdaw.com
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