Digital circuit for the introduction of dither into an analog signal

Abstract

An electronics circuit for digitizing an analog audio data signal into a ital equivalent signal and then introducing digitized nyquist dither data into the digital equivalent signal to substantially eliminate the need for removing the nyquist dither data from the digital equivalent signal prior to its conversion to an analog signal which is a substantial replica of the incoming analog audio or like data signal. The electronics circuit comprises a first pseudo-random number generator which generates a series of digitized nyquist dither bits for addition to the digital equivalent signal. The digitized nyquist dither bits are, in turn, provided by an external computer using a computer program which first generates a pseudo-random sequence of positive integers over a first predetermined range. The computer program implements a high pass filter which processes the pseudo-random sequence of positive integers to generate the digitized nyquist dither bits for use by the programmed read only memory as the dither bits to be added to the digital equivalent signal. A binary adder adds the digitized nyquist dither bits to the digital equivalent signal and then provides the resulting digital equivalent signal with dither to a first clipping circuit. The first clipping circuit clips the digital equivalent signal with dither to a maximum binary value having every bit at the logic one state and a minimum binary value having every bit at the logic zero state.