ACCURATE LOG AND INVERSE-LOG FUNCTION GENERATING CIRCUITS: FOR USE IN DIGITAL VOCODER PITCH CHANNEL,
Abstract
A novel synthesis technique, empirical in na ture, is developed for diode-resistance func tion generation circuits attaining accuracies higher than theoretically possible by classic methods of peicewise-linear approximation. By the technique, analog signals applied to a non linear function generating network transitional ly switch diode-resistance network branches. Curvi-linear rather than piecewise-linear ap proximation segments are thus generated. This is achieved by resistive non-linear network attenua tion techniques which take advantage of the transitional resistance states assimulated by a germanium diode during its switching cycle. The resulting network attentuation characteristic can thus be made to closely approximate a monotonic function. In particular, logarithmic and ex ponential (inverse-log) function generating tech niques are discribed. To justify the empirical synthesis technique, a varied theoretical analy sis is first carried out. Logarithmic and ex ponential functions are graphically and mathe matically reviewed. A novel presentation of diode characteristics and their equivalent cir cuits is given. Classic function generating cir cuit theory is reviewed using a basic model from which the transitional-resistance model is then developed. Implementation of the dynamic models into the AFCRL digial vocoder and data processor is described including tables of quantum fre quencies and voltages, calibration data and cir cuit diagrams. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1963
- Accession Number
- AD0413479
Entities
People
- Lawrence V. Kriger
Organizations
- Air Force Cambridge Research Laboratories