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Digital Signal Processing

Discrete-time signals and systems, the z-transform, sampling, the DFT and FFT, and digital filter design -- built on Fourier Analysis and Probability, with every technique answering "what does this do to a real signal?"

Free to read now, no account needed: Readiness review. Create a free account to open the other chapters, take the quizzes and keep your progress.

1 Classifying signals and systems πŸ”’

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  • Deterministic vs. random, periodic vs. aperiodic signals ~12 min
  • Energy signals and power signals ~12 min
  • Even and odd signals, and the even/odd decomposition ~12 min
  • Exponential and sinusoidal sequences ~12 min
  • Sequence transformations: shifting and reflection ~12 min
  • Sequence transformations: time-scaling and amplitude-scaling ~12 min
  • System properties: memory, causality, and stability ~14 min
  • Linearity and time-invariance -- why LTI systems are special ~14 min
  • A DSP application survey ~10 min

2 Convolution and difference equations πŸ”’

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  • The convolution sum, derived from the sifting property ~14 min
  • Graphical and analytical convolution evaluation ~14 min
  • LTI system properties via convolution algebra ~12 min
  • Numerical convolution: stream vs. block processing ~14 min
  • Linear constant-coefficient difference equations ~14 min
  • Recursive vs. non-recursive systems, and what that means for memory ~12 min
  • Homogeneous and particular solutions ~14 min
  • Zero-input and zero-state response ~12 min
  • Real-time FIR implementation, a first look ~12 min

3 The Fourier representation of discrete-time signals πŸ”’

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  • The Fourier transform, its properties, and the convolution theorem, revisited ~12 min
  • Discrete-time sinusoid periodicity, revisited for the frequency domain ~10 min
  • The discrete-time Fourier transform (DTFT), defined ~14 min
  • DTFT properties ~12 min
  • Periodicity of the DTFT ~10 min
  • The four Fourier representations, unified ~12 min
  • Magnitude and phase spectra: reading a DTFT ~12 min
  • Relating a system's frequency response to its difference equation ~12 min

4 Transform analysis of LTI systems πŸ”’

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  • Sinusoidal steady-state response ~12 min
  • Frequency-domain response to general inputs ~10 min
  • Magnitude and phase (group-delay) distortion ~12 min
  • Ideal vs. practical filter types: tolerance diagrams ~12 min
  • The z-transform: why a transform beyond the DTFT is needed ~10 min
  • The z-transform: definition, region of convergence, and common pairs ~14 min
  • The inverse z-transform ~14 min
  • Z-transform properties ~12 min
  • Poles, zeros, and the system function H(z) ~14 min

5 Poles, zeros, and system behavior πŸ”’

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  • Pole-zero geometry and time-domain behavior ~12 min
  • The vector argument for frequency-response shape ~12 min
  • A first filter design by direct pole-zero placement ~12 min
  • Magnitude-phase relationships ~12 min
  • Allpass systems ~12 min
  • Minimum-phase systems and minimum-phase/allpass decomposition ~14 min
  • Invertibility of LTI systems ~12 min
  • Why pole-zero intuition is load-bearing for filter design ~10 min

6 Sampling and reconstruction πŸ”’

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  • Recall: the Nyquist-Shannon theorem and aliasing ~10 min
  • The "impersonation" framing of aliasing ~10 min
  • Ideal reconstruction and bandlimited (sinc) interpolation ~12 min
  • Practical, non-ideal sampling and reconstruction ~12 min
  • The sandwich model of continuous-signal processing ~10 min
  • Bandpass sampling ~12 min
  • Deliberately violating the Nyquist criterion ~10 min
  • A first look at quantization ~8 min
  • Two-dimensional sampling ~8 min

7 The Discrete Fourier Transform πŸ”’

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  • Recall: the DFT definition and circular convolution ~12 min
  • Why only the DFT is exactly computable ~10 min
  • The DFT as a sampled DTFT ~10 min
  • Linear convolution via the DFT and zero-padding ~14 min
  • Spectral leakage ~12 min
  • Window functions and their trade-offs ~14 min
  • The spectrogram of a synthesized signal ~12 min
  • Fourier-based signal analysis, worked end to end ~12 min

8 The Fast Fourier Transform πŸ”’

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  • Direct DFT computation: an O(NΒ²) baseline ~10 min
  • The FFT idea via matrix factorization ~14 min
  • Decimation-in-time FFT and the butterfly diagram ~14 min
  • Decimation-in-frequency FFT ~12 min
  • Bit-reversal and in-place computation ~12 min
  • O(N log N) versus O(NΒ²), measured ~10 min
  • Other FFT families ~8 min

9 Structures for discrete-time systems πŸ”’

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  • Block diagrams and signal-flow graphs ~10 min
  • Direct form I and direct form II ~12 min
  • Cascade and parallel structures ~12 min
  • FIR structures and the linear-phase folded form ~12 min
  • Lattice structures and reflection coefficients ~14 min
  • The lattice-coefficient stability test ~12 min
  • Why structure choice matters: coefficient sensitivity ~10 min

10 Design of FIR filters πŸ”’

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  • The filter-design problem: five stages ~10 min
  • Linear-phase FIR filters and the four symmetry types ~12 min
  • The windowing method ~12 min
  • The frequency-sampling method ~12 min
  • Chebyshev polynomials and minimax approximation ~12 min
  • The Paley-Wiener theorem ~12 min
  • The alternation theorem and equiripple design ~14 min
  • Special FIR filters: differentiators ~10 min
  • Special FIR filters: Hilbert transformers ~10 min

11 Design of IIR filters πŸ”’

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  • The Butterworth analog prototype ~12 min
  • The Chebyshev I analog prototype ~12 min
  • Chebyshev II and elliptic prototypes ~10 min
  • The three conditions for a valid transformation ~10 min
  • The impulse-invariance transformation ~12 min
  • The bilinear transformation ~12 min
  • Frequency prewarping ~10 min
  • Frequency transformations: lowpass to highpass, bandpass, bandstop ~12 min
  • Choosing FIR vs. IIR ~10 min

12 Random signals πŸ”’

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  • Recall: random variables, joint distributions, and covariance ~10 min
  • Why deterministic-signal tools don't apply to random signals ~10 min
  • Stationarity of random processes ~10 min
  • Wide-sense stationarity and ergodicity ~12 min
  • The autocorrelation sequence ~12 min
  • Power spectral density ~12 min
  • White noise and AR/MA/ARMA process models ~12 min
  • Linking process statistics to filter design ~10 min

13 Random signal processing πŸ”’

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  • Estimating statistics from data: bias, consistency, asymptotic unbiasedness ~12 min
  • The periodogram: a poor PSD estimator ~12 min
  • Bartlett and Welch averaging ~12 min
  • The Wiener filter and the orthogonality principle ~14 min
  • The matched filter and signal detection ~12 min
  • Cross-correlation for time-delay estimation ~10 min
  • Linear prediction and all-pole modeling ~14 min
  • The Karhunen-LoΓ¨ve transform ~12 min

14 Multirate signal processing πŸ”’

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  • Decimation, downsampling, and anti-aliasing ~12 min
  • Interpolation, upsampling, and anti-imaging ~12 min
  • Rational-factor sample-rate conversion ~12 min
  • Polyphase decomposition and the noble identities ~12 min
  • Half-band filters and interpolated FIR (IFIR) design ~12 min
  • Two-channel filter banks: quadrature mirror filters and perfect reconstruction ~14 min
  • Why multirate design is a systems-engineering trade-off ~10 min

15 Finite wordlength effects πŸ”’

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  • Fixed-point, floating-point, and two's-complement number representation ~12 min
  • The uniform quantization-noise model ~12 min
  • Signal-to-quantization-noise ratio (SQNR) ~12 min
  • Oversampled A/D and D/A conversion, noise shaping, and a first look at sigma-delta ~12 min
  • Filter-coefficient quantization and pole/zero sensitivity ~12 min
  • Limit cycles and overflow oscillation in fixed-point IIR filters ~12 min
  • Finite-wordlength effects in FFT algorithms ~10 min
  • What "no extensive math background" claims miss: calibrating this course's own difficulty honestly ~8 min

16 The 2D DSP connection: from signals to images πŸ”’

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  • Recalling 1D convolution and the 1D DFT ~10 min
  • 1D vs. 2D signals: an image as a 2D array ~10 min
  • 2D convolution ~12 min
  • 2D correlation ~12 min
  • The 2D DFT and separability ~12 min
  • Spatial aliasing and 2D downsampling ~12 min
  • What a dedicated Digital Image Processing course adds ~14 min