Abstract: A filter bag support member for fastening a filter bag to an apertured bag header plate member disposed between the dirty gas inlet and the clean gas outlet of a filter bag housing comprising a flow-through venturi-like tube having one end releasably fastened to the plate member and a clamp at the other end receiving the filter bag in supporting sealed relation.

Abstract: A filter housing having one or more flow-through media support members releasably secured in the housing between the dirty gas inlet and the clean gas outlet to divide the housing into a dirty gas chamber and a clean gas chamber.

Abstract: A secure communication system for transmitting and receiving an encoded information signal. The system generates at transmitting and receiving locations a predetermined unique pseudorandom code. A synchronized tracking signal is imposed on the information to be transmitted and added to the information to form an intermediate signal. The pseudorandom code is then multiplied by the intermediate signal directly so that the ultimate result appears to assume the character of pseudorandom noise, which is then transmitted to the receiving location. The synchronization and transmitted encoded portion is decoded at the receiver and used to generate a base signal for a pseudorandom generator at the receiving location, as well as initiate initial clocking pulse time for operation of the receiver pseudorandom generator.