The first part of this thesis is a general review of signal processing. Correlation theory is discussed with special reference to quantized signals and a number of techniques for correlation function measurements are described and evaluated. The second part of the thesis deals with the design considerations and practical aspects of building an inexpensive hybrid correlator. One was breadboarded and tested by measuring the autocorrelation functions of 3one signals. A practical design is presented and suggestions for improvements are made. It is concluded that this hybrid technique is a powerful method for online determination of correlation functions.