On design of continuous-and-discrete extremum control systems immune to low frequency disturbances

The paper is concerned with behaviour of nonsearehing continuous-and-discrete systems with synchronous detection in face of drift of the extremum characteristic. It is shown that in conventional systems with odd searching signals the stability is limited by the rate of horizontal drift while the search performance is unsatisfactory because of significant scatter of the steady state mode due to variations in the horizontal and vertical drift rate. The use of ecen searching signals is shown to remove stability constraints on the drift velocity and eliminates the effect of vertical drift on the searching performance.