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An Overview of Delay-and-sum Beamforming

DSP Seminar (1 st semester, 2006 - 2007). An Overview of Delay-and-sum Beamforming. Outline. Objective Introduction Delay-and-sum Beamforming Future Works Q & A. Objective. Design a small-dimensional microphone array for beamforming in an acoustic environment with the presence of noises.

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An Overview of Delay-and-sum Beamforming

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  1. DSP Seminar (1st semester, 2006 - 2007) An Overview of Delay-and-sum Beamforming

  2. Outline • Objective • Introduction • Delay-and-sum Beamforming • Future Works • Q & A

  3. Objective Design a small-dimensional microphone array for beamforming in an acoustic environment with the presence of noises

  4. Introduction (1) Microphone • Characterized by a spatial directivity pattern, which specifies the gain and phase shift that the microphone gives to a signal coming from a certain direction (angle-of-arrival)

  5. Introduction (2) Spatial directivity pattern • Function of angle-of-arrival and frequency • Transfer function for source of a particular frequency  at angle 

  6. Spatial filtering Introduction (3) Received signals from different microphones Filtering Summing “Virtual” spatial directivity pattern

  7. Introduction (4) Spatial filter design is based on two factors • Microphone characteristics • Microphone array configuration

  8. Introduction (5) Beamforming • Can be thought of as spatial filtering • Can increase the receiver sensitivity in the direction of wanted signals • Can decrease the receiver sensitivity in the direction of interferences and noises

  9. Covered in this seminar Introduction (6) Two categories of beamforming • Fixed beamforming • Delay-and-sum beamforming • Weighted-sum beamforming • Filter-and-sum beamforming • Adaptive beamforming • LCMV beamforming • Generalized sidelobe canceller

  10. Introduction (7) Basic differences between fixed and adaptive beamforming

  11. Introduction (8) Assumptions • Microphone gain = 1 at all angles for all frequencies • Far-field source (plane waveforms)

  12. Delay-and-sum Beamforming (1)

  13. Delay-and-sum Beamforming (2)

  14. Delay-and-sum Beamforming (3) Simulation settings • Number of microphones M = 5 • Distance between neighbouring microphones d = 0.03 m • Sampling frequency fs = 16 kHz • Source frequency f = 5000 Hz

  15. Delay-and-sum Beamforming (4)

  16. Future Works • Investigate into adaptive beamforming, e.g. GSC, which has the ability to minimize noises • Perform simulations to compare the performances of various existing types of adaptive beamforming in a noisy environment

  17. Reference Microphone Array Processing, Marc Moonen, Dept. E.E., EAST, K.U.Leuven

  18. Q & A Thank You!

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