A noise-adaptive digital null detector

This paper describes a digital null detector which is able to detect sinusoidal signals in the presence of correlated noise. It is therefore well suited for applications with multiple digital signal generators. In particular, it is shown that the apparatus is suitable for separating the glitch pulses of digital-to-analog converters from sinusoidal signals. Numerical simulations on the influence of harmonic distortion are also presented. Measurement uncertainties on a prototype were seen to be up to six times smaller than on comparable lock-in algorithm-based null detectors.