A method for the design of phase-lead demodulating compensators for use in carrier control systems

A fairly new type of compensator for carrier control systems consists of a passive electric network that contains one or more periodically-conducting branches. This type of compensator (referred to as a demodulating compensating network) is superior to other types, used previously, in terms of size, weight, cost, and sensitivity to variations in carrier frequency. Although a detailed analysis of the operation of a demodulating compensating network is usually very tedious, it is possible to describe the effect of such a network in a feedback control system very simply by the use of an equivalent time-invariant passive electric network. A procedure for designing a phase-lead demodulating compensating network to meet specifications on system performance is presented in this paper. In essence, this procedure consists of the following steps. First, the uncompensated frequency response of the system is examined. Then an acceptable and realizable phase and/or gain characteristic is selected. Finally, by the use of design curves, the parameters of the demodulating compensator required to provide the desired frequency response are determined. Numerical examples are included to illustrate the application of the design procedure, and experimental results are reported to reveal the value of the procedure.