Abstract: A digital discriminator having circuit means for discriminating a unidirectional transient in the input signal over a two or more compute cycle period. Noise spike clipping by providing a programmable constant in a feedback circuit is disclosed and serves to clip the signal in one given direction giving positive sensitivity of that signal in the other direction.

Abstract: An annular ram burner has a movable wall adjacent the flameholder to provide a large variation in area change at the flameholder plane. The movable wall comprises a number of flaps mounted around the ram burner. While a ram burner is shown a fan duct burner can also be used. The flaps are attached to an actuator mechanism through a linkage system which allows the wall to be moved rapidly and to be simply controlled by an engine control device, substantially in the same manner that the variable area exhaust nozzle is controlled. The flaps further are provided with a liner so that cooling air is directed therethrough to an annular liner around the combustion chamber.