The design of the digital electronics of the field test unit was shifted to an IBM AT compatible base, and special digital-to-analog and analog-to-digital boards for the field test unit were designed and their construction begun. Alternate technologies for airborne ultrasound transmitters and receivers for the field test unit were identified and their incorporation into the detection system begun. The demonstration unit designed and built detected four natural frequencies among three known handguns, automatically, in less than 1 second. A literature search and studies with three animal models showed that the ultrasound used by the detection system does not pose a biohazard. This report recommends that a Phase III be undertaken to complete the development of the Hallway Version of the field test unit and begin field testing the unit. Procedures for this are proposed.