Limiting resolution of Capon method for correlated sources

Authors

  • A. A. Kirillov Nizhny Novgorod State University, Russian Federation
  • G. V. Serebryakov Nizhny Novgorod State University, Russian Federation

DOI:

https://doi.org/10.1109/ICATT.1999.1236166

Abstract

Use of the optimum/adaptive beamforming (so called, Capon method) in bearing estimation of closely located sources has become very popular due to its superresolution properties [1–4]. It has been shown that this method is capable of resolving two independent sources which are separated by an angle which is of the order of one standard beamwidth (SBW) and sometimes less. However, when some sources are fully or highly correlated (coherent), i.e. when one source is a scaled and delayed replica of another source, this method encounters significant difficulties concerning with signal cancellation effect [2, 3, 6, 7]. Note that coherent sources appear frequently in practical problems. A well-known example is the phenomenon of multipath propagation.

The purpose of this paper is to obtain analytical estimation of the potential capability for adaptive beamforming in the presence of correlation between the sources as a function of coherence coefficient, signal power and the parameters of the optimum processor. Our resolution analysis is based on the assumption that the covariance matrix of the received signal will be determined rigorously by averaging over an infinite period of time, thus enabling us to obtain an estimate of the limiting ability of resolution.

References

Capon, J. High-resolution frequency-wavenumber spectrum analysis. Proc. IEEE, 1969, Vol. 57, p. 1408-1418.

Gabriel, W. Spectral analysis and adaptive array superresolution techniques. Proc. IEEE, 1980, Vol. 68, p. 654-666.

De Graaf, S.; Johnson, D.H. Capability of array processing algorithms to estimate source bearings. IEEE Trans. Acoust., Speech, Signal Processing, 1985, Vol. ASSP-33, p. 1368-1379.

Cox, H. Resolving power and sensitivity to mismatch of optimum array processor. JASA, 1973, Vol. 54, p. 771-785.

White, W. Angular spectra in radar applications. IEEE Trans. Aerospace Electron. Syst., 1979, Vol. AES-15, p. 895-899.

Cantoni, A.; Godara, L.C. Resolving the directions of sources in a correlated field incident on an array. JASA, 1980, Vol. 67, p. 1247-1256.

Shan, T.; Kailath, T. Adaptive beamforming for coherent signals and interference. IEEE Trans. Acoust., Speech, Signal Processing, 1985, Vol. ASSP-33, p. 527-536.

Published

1999-09-14

Issue

Section

AA, AAA, smart antennas and signal processing