Piezoelectric shock wave detector

A shock or pressure wave detecting transducer assembly for detecting air-borne shock or pressure waves generated on movement of a projectile therepast, said transducer comprising, a head, said head having a hemispherical front surface to receive shock or pressure waves received over a wide range of angles of incidence of up to approximately 80.degree. with respect to a central axis of the transducer assembly and to transmit them to a point on the rear face, which is at the centre of said hemispherical front surface characterized by;

• a transducer element mounted behind said head and connected with the rear face of the head by a zone which embraces said point, said zone being substantially smaller in cross sectional area measured perpendicular to the propagation direction through said zone than that of said rear face, the element being responsive to those pressure or shock waves which propagate through said zone, said zone comprising a means for providing polar response signal outputs from said element, said outputs having the same signal polarity and do not have a zero value over said wide range of the angles of incidence.

A shock or pressure wave detecting transducer assembly for detecting air-borne shock or pressure waves generated on movement of a projectile therepast, said transducer comprising a head for receiving said shock or pressure waves and a transducer element mounted behind said head and connected with the rear face thereof;

• said head and said transducer element being mounted by mounting means on a body which is used for fastening said transducer assembly to frame means characterized by;
• said mounting means comprising means for enhancing isolation of frame borne shock or pressure waves from said head and permitting high stability of the position of mounting of said transducer assembly to said frame said enhancing means comprising a series path of acoustic mismatches between said head and said body, said path including at least four interfaces.

A shock or pressure wave detecting transducer assembly for detecting air-borne shock or pressure waves on movement of a projectile therepast, said transducer comprising a head, said head having a front surface to receive shock or pressure waves received over a wide range of angles of incidence of up to approximately 80.degree. with respect to a central axis of the transducer assembly and to transmit them to a point on the rear face thereof, a transducer element comprising a piezoelectric member connected with said rear face by a spigot which embraces said point, said spigot being substantially smaller in cross sectional area measured perpendicular to the direction of propagation of shock or pressure waves through said spigot than that of said rear face characterized by;

• said piezo-electric element being mounted within an electrically conductive tube which has a partly closed end, said piezo-electric element being mounted at said partly closed end so that one face of said piezo-electric element electrically connects with said partly closed end and wherein said spigot connects with said one face of said piezo-electric element through an opening in said partly closed end whereby electrical connection to said one face can be obtained by taking a lead from the other end of said tube.