Optimum Linear Amplitude-Continuous Block Codes.
Berkowitz,Sidney · Defense Technical Information Center (DTIC) · 1971
In transmitting data--say, speech or sonar signals--over a noisy channel, or in making measurements with imprecise instruments, i.e., instruments subject to a fluctuating error having some statistical regularity, it is possible to improve the accuracy of reception or measurement at the expense of bandwidth by a redundant mapping of the original signal space into a higher-dimensioned space. The mapping considered in this report is a linear transformation of a vector of unquantized signal samples. The transformation is called a linear amplitude-continuous (LAC) block code, and takes the form of a real-valued, rectangular matrix transformation A of a vector of real-valued, zero-mean signal samples with covariance matrix R sub x such that the average signal input/output power ratio is invariant over the coding process. A special class of LAC codes, called orthogonal codes, is constrained by (A sup T)A is proportional to I. (Author)