Abstract: The invention relates to a two state phase modulator with minimum amplitude modulation. The modulator assumes two phase states differing by .THETA. where .THETA. is a sub-multiple of 180.degree. which permits a phase variation of 180.degree. for phase coded transmissions when the frequency of the phase modulated carrier wave is multiplied by the reciprocal of the sub-multiple. Three equal components are derived in the phase modulator: an in-phase, an out of phase, and a quadrature phase component. The out of phase component is delayed in relation to the in-phase component by .THETA./2, while the quadrature phase component is delayed .THETA./4. The in-phase and out of phase components are then reduced by a factor (2 sin .THETA./2) selected such that when added to the quadrature component, the resultants have a magnitude equal to that of the quadrature component and differ in phase from the quadrature comonent by .+-..THETA./2.

Abstract: An intermediate frequency sidelobe canceller of the kind including a cancellation loop, with provision added for programming the correlation signal weights which control operation of the loop. This capability is provided by switch means interposed in the cancellation loop within the correlation signal branch thereof and selectively operable to break the loop and then either to substitute for the normally weighted correlation signal to the canceller another signal of different weighting, such as an externally supplied signal, or to retain or "hold" the current value of the correlation signal. Such substitution affords improved canceller operation and adaptability to otherwise difficult operating conditions such as strong clutter and transmitted pulse interference.