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Abstract

Apparatus for the cross-correlation of two complex sampled digital data signals X and Y uses a first N-stage CORDIC rotator of pipeline sequential form for rotating each of the real and imaginary data portions of the first (X) complex sampled signal sequentially through a summation of angles .theta.=.xi..sub.i .alpha..sub.i where .xi..sub.i =+1 or -1, .alpha..sub.1 =90.degree. and .alpha..sub.n-2 =tan.sup.-1 (2.sup.-n) for n=0, 1, 2, 3, . . . N-2) until X.sub.Im is approximately zero and a substantially zero phase angle is reached. The sign from each i-th stage, of this first pipeline is also utilized to determine the sign of rotation in each like-positioned i-th stage of a plurality M of additional CORDIC pipeline rotators, where M is the total number of time delays at which the cross-correlation function is evaluated. The real and imaginary portions of the complete M-th interval cross-correlation product are each obtained by multiplying the associated complex output of each of the Y pipeline rotators by the first pipeline magnitude signal output; N samples are then summed to provide at the j-th rotator output the appropriate pair of the real and imaginary parts of the j-th complex digital data output sample C(j).

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