Constant beamwidth receiving arrays for broadband detection and power estimation of signals
J. Lardies, J. P. Flenner · The Journal of the Acoustical Society of America · 1986
The detection at low frequencies and power estimation of broadband signals may often be accomplished with an array of sensors. Four beamformers are studied; the conventional end-fire beamformer, and the maximum-likelihood estimator, the maximum-entropy estimator, and a new broadband constant beamwidth beamformer. It is shown that it is impossible to detect and estimate the power of small signals at low frequencies by the conventional end-fire array, by the maximum-likelihood, or by the maximum-entropy methods. An algorithm with superior low-frequency performance is studied. The proposed method estimates the signal powers from the correlation between sensors. We find that the beamwidth of the processor is remarkably insensitive to frequency variations and is under operator's control. This technique may detect and estimate the power of signals, at low frequencies, which could not be found using the other techniques.