Linear signal processing systems consisting of time-invariant circuits and carrier-actuated modulators are widely used. An analysis program, PAMS, developed specifically for such systems, and its application for design and analysis (including sensitivity studies) is discussed. Two application examples are given: namely (a) the variation of a single design parameter is shown to vary the response of a two-path filter from that of a lowpass to that of a bandpass filter, and the variation of a hardware parameter is shown to produce ‘forbidden’ output frequencies; and (b) two versions of a quadrature modulation-type vestigial sideband system are analysed; the suitability of two different filtering symmetry conditions is demonstrated, but the sensitivity of the system amplitude and phase responses to carrier-phase errors is shown to depend on the symmetry condition chosen.