The Effects of Clipping on Linear Beamforming With Sinusoidal Inputs.
PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB
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The problem addressed in this thesis is the overload of a linear transducer array. Under normal conditions, such overload results in clipping of the input signal. Such clipping may occur at the array elements or at the output of the beamformer with differing results. This paper presents a comparative study of the effect on beamformer performance of clipping at the transducer elements and of clipping at the beamformer output for sinusoidal signal and interference. The study was made using a computer simulation of a linear, single-line array connected to a bandpass spectrum analyzer. It was found that even hard clipping, i.e., clipping at a level far below that of the input signals, at the transducer elements had very little effect on the directivity of the array. Clipping at the output of the beamformer was found to have considerable effect on the directivity. This effect was strongly dependent upon the signal-to-interference ratio and upon the signal level at which clipping occurred. It was concluded that the beamformer should be designed so as to guarantee that if clipping is to occur, it be made to take place at the elements. Author
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