Constant Directivity Beamforming
Beamforming, or spatial filtering, is one of the simplest methods for discriminating between different signals based on the physical location of the sources. Because speech is a very wideband signal, covering some four octaves, traditional narrowband beamforming techniques are inappropriate for hands-free speech acquisition. One class of broadband beamformers, called constant directivity beam-formers, aim to produce a constant spatial response over a broad frequency range. In this chapter we review such beamformers, and discuss implementation issues related to their use in microphone arrays.
KeywordsAcoustics Sonar Aliasing Dole
Unable to display preview. Download preview PDF.
- 3.J.L. Flanagan, D.A. Berkeley, G.W. Elko, J.E. West, and M.M. Sondhi, “Autodirective microphone systems,” Acustica, vol. 73, pp. 58–71, 1991.Google Scholar
- 4.W. Kellermann, “A self-steering digital microphone array,” in Proc. IEEE Int. Conf. Acoust., Speech, Signal Processing (ICASSP-91), 1991, vol. 5, pp. 3581–3584.Google Scholar
- 5.F. Khalil, J.P. Jullien, and A. Gilloire, “Microphone array for sound pickup in teleconference systems,” J. Audio Eng. Soc., vol. 42, no. 9, pp. 691–700, Sept. 1994.Google Scholar
- 6.J. Lardies, “Acoustic ring array with constant beamwidth over a very wide frequency range,” Acoust. Letters, vol. 13, no. 5, pp. 77–81, 1989.Google Scholar
- 7.R. Smith, “Constant beamwidth receiving arrays for broad band sonar systems,” Acustica, vol. 23, pp. 21–26, 1970.Google Scholar
- 8.M.M. Goodwin and G.W. Elko, “Constant beamwidth beamforming,” in Proc. IEEE Int. Conf. Acoust., Speech, Signal Processing (ICASSP-93), 1993, vol. 1, pp. 169–172.Google Scholar
- 10.A. Ishimaru, “Theory of unequally-spaced arrays,” IRE Trans. Antennas Propagat., vol. AP-10, pp. 691–702, Nov. 1962.Google Scholar
- 11.A. Ishimaru and Y.S. Chen, “Thinning and broadbanding antenna arrays by unequal spacings,” IEEE Trans. Antennas Propagat., vol. AP-13, pp. 34–42, Jan. 1965.Google Scholar
- 12.T. Chou, “Frequency-independent beamformer with low response error,” in Proc. IEEE Int. Conf. Acoust., Speech, Signal Processing (ICASSP-95), Detroit, USA, May 1995, pp. 2995–2998.Google Scholar
- 13.S. Haykin and J. Kesler, “Relation between the radiation pattern of an array and the two-dimensional discrete Fourier transform,” IEEE Trans. Antennas Propagat., vol. AP-23, no. 3, pp. 419–420, May 1975.Google Scholar
- 14.J.S. Marciano Jr. and T.B. Vu, “Reduced complexity beam space broadband frequency invariant beamforming,” Electronics Letters, vol. 36, no. 7, pp. 682683; Mar. 2000.Google Scholar
- 17.C. Winter, “Using continuous apertures discretely,” IEEE Trans. Antennas Propagat., vol. AP-25, pp. 695–700, Sept. 1977.Google Scholar