CHAPTER 10 Applications of Digital Signal Processing

1. CHAPTER 10 Applications of Digital Signal Processing Wang Weilian wlwang@ynu.edu.cn School of Information Science and Technology Yunnan University

2. Outline • Speech Signals Processing • Dual-Tone Multifrequency Signal Detection 云南大学滇池学院课程：数字信号处理

3. Speech Signals Processing • Speech Analysis • parameterize the speech signal • To reduce the bandwidth • To characterize the speech signal with only a few features • Speech Signal Processing is one of the kernel technologies in those fields as follows: Information Superhighway, Multimedia, OAS (office automation system), Modern Communications System, Intelligent System and so on. 云南大学滇池学院课程：数字信号处理

4. Speech Signals Processing • Speech Analysis — time-domain • data windowing: Windowing Calculation 云南大学滇池学院课程：数字信号处理

5. Speech Signals Processing • Speech Analysis — time-domain • Energy: • Selecting 10ms ~ 30ms as the length of the window in general 云南大学滇池学院课程：数字信号处理

6. Speech Signals Processing • Speech Analysis — time-domain • The zero crossing rate ( ZCR ): • where 云南大学滇池学院课程：数字信号处理

7. Speech Signals Processing • Speech Analysis — time-domain • Energy and ZCR: Energy and ZCR 云南大学滇池学院课程：数字信号处理

8. Speech Signals Processing • Speech Analysis — time-domain • The Autocorrelation function: • If , then: 云南大学滇池学院课程：数字信号处理

9. Speech Signals Processing • Speech Analysis— time-domain • The Autocorrelation function: The block diagram of the autocorrelation function 云南大学滇池学院课程：数字信号处理

10. Speech Signals Processing • Speech Analysis — frequency-domain • Fourier Transform and Spectrogram The filter-explanation of the FT 云南大学滇池学院课程：数字信号处理

11. Speech Signals Processing • Speech Analysis — frequency-domain • The spectrogram: The spectrogram 云南大学滇池学院课程：数字信号处理

12. Speech Signals Processing • Speech Analysis — frequency-domain • Spectra analysis • The power spectra ( energy density function ): • Complex Ceptrum: • Quefrency: 云南大学滇池学院课程：数字信号处理

13. Speech Signals Processing • Speech Analysis — frequency-domain • Linear Predictive: • The model of signal generation Autoregressive Moving Average Model 云南大学滇池学院课程：数字信号处理

14. Speech Signals Processing • Speech Analysis — frequency-domain • Linear Predictive: • G is the gain factor. • U(z) / S(z) is the Z-Transform of input / output sequence 云南大学滇池学院课程：数字信号处理

15. Speech Signals Processing • Speech Analysis — frequency-domain Linear Predictive ( autocorrelation method ) 云南大学滇池学院课程：数字信号处理

16. Speech Signals Processing • Speech Synthesis • Formant Synthesis: the transfer function of formants can be simulated by using a 2th-order digital filter generally. 云南大学滇池学院课程：数字信号处理

17. Speech Signals Processing • Speech Recognition Communication via Spoken Language 云南大学滇池学院课程：数字信号处理

18. Dual-Tone Multifrequency Signal Detection • A DTMF signal consist of a sum of two tones with frequencies taken from two mutually exclusive groups of preassigned frequencies. • Each pair of such tones represents a unique number or a symbol. 云南大学滇池学院课程：数字信号处理

19. Dual-Tone Multifrequency Signal Detection • Decoding of a DTMF signal thus involves identifying the two tones in that signal and determining their corresponding number or symbol. • The DTMF decoder computes the DFT samples closest in frequency to the eight DTMF fundamental tones and their respective second harmonics. • The DFT length N determines the frequency spacing between the locations of the DFT samples and the time it takes to compute the DFT sample. The frequency corresponding to the DFT index ( bin number ) k is: 云南大学滇池学院课程：数字信号处理