Abstract: A plurality of submerged control station junction boxes each include a microprocessor having data storage and transmission capability, airgun firing and related electronic circuits to control a predetermined airgun or airgun groups. These junction boxes are towed at spaced positions along an airgun array. An electrical cable and sections of high pressure air supply line are detachably coupled to each junction box. The predetermined airguns to be controlled by a junction box are detachably coupled thereto. Thus, the number of airguns in the towed array can be changed by coupling or uncoupling junction boxes and the associated airguns controlled by them. The junction boxes are automatically cooled on shipboard by increasing low pressure air until a relief valve opens for establishing a continuous cooling flow of low pressure through a protective hose sheath and the junction boxes.

Abstract: A variable reluctance type firing sensor is mounted on an air gun for providing an electrical signal indicative of the instant of firing of the air gun. The firing sensor has a magnetic circuit which includes a permanent magnet, a pair of pole pieces and an armature including magnetically permeable material and which is free of mechanical restraint in its normal operating position, being held by magnetic attraction in position in the magnetic circuit. The armature freely "floats" on its "magnetic springs" within a thin walled chamber in which it is housed between the pole pieces, assuming a predetermined position of least magnetic reluctance. The armature which is acceleration-responsive is suddenly displaced from its predetermined position upon the firing of the air gun, and thus the reluctance of the magnetic circuit abruptly increases at the instant of firing.

Abstract: An air gun firing sensor apparatus and system are provided for determining the instant of firing of an air gun by sensing pressure changes within the air gun when it is being fired. A pressure-change-sensitive transducer assembly is inserted into a socket in the housing of a solenoid-controlled valve of an air gun with a passage from the air gun communicating with the transducer for transmitting to the transducer a pressure surge occurring within the air gun whenever it is fired. The transducer assembly has a cylindrical casing with a head mounted at one end. The head includes a plurality of spaced recesses which are adapted to communicate with the passage leading from the air gun.