Application of the normal spectrum technique to the calculation of distortion noise in delta modulators

The paper establishes the theoretical behaviour of the linear delta modulator with the aid of the normal spectrum technique. The spectral density functions of the signal at the output of the decoder and of the distortion due to quantization effects are calculated for band-limited white noise input signals. The expressions of these spectral density functions derived with the normal spectrum technique enable the results of computer simulation to be easily explained. Graphical results are presented of the spectral density function of the distortion signal for the coder having different step-sizes and clock rates, and of the decoded signal to noise ratio against input signal power. The computer simulation verifies the authenticity of the theory.