Abstract: A volumetric/planar array structure for detection of low frequency active pulses in shallow water. The structure is such that the array can be repeatedly deployed and retrieved. The invention utilizes folding array arms that are deployed at a pre-selected depth using only gravity once the release mechanism for deployment has been initiated. Rigid vertical support rods attach to all array levels preventing rotation down below the desired horizontal position during operation. Retraction of array arms for array structure retrieval is initiated by activating an electronic underwater release mechanism which then allows compliant rubber members to pull array arms in place. Once the array arms are in place, they are protected by a skid/crash cage fixture and the array structure is then ready for retrieval.

Abstract: Users of facsimile communications systems may test their fax transceivers by transmitting a test fax page over the public switched telephone network to a system that makes measurements of the test transmission and of telephone line characteristics. Measurements are analyzed to locate possible anomalies. Results of analysis, the measurements themselves and a copy of the user's test fax are incorporated into a test report. The test report is delivered to users as a fax message or spoken announcement during the same call or a second call.

Abstract: Mobile air cleaning apparatus comprising a base, a cabinet which is mounted on and extends upwardly from one end of the base, and a hood which is supported by the upper end of the cabinet and extends over the base. A circular air flow path is formed which includes the open space between the hood and the base, and ducts in the base, the cabinet and the hood. In the air flow path are particle filters, an activated carbon filter, and a blower. The base is mounted on wheels so that the entire apparatus is readily movable.