Abstract: A positioning, communication, and detection system designed to provide a three dimensional location of an object, navigation tools, and bidirectional surface-to-subsurface communications, and methods of using the system. The system can include one or multiple transmitters comprising electromagnetic beacons, software defined radio receivers with an associated processing unit and data acquisition system, and magnetic antennas. The system may use theoretical calculations, scale model testing, signal processing, and sensor data.

Abstract: A positioning, communication, and detection system designed to provide a three dimensional location of an object, navigation tools, and bidirectional surface-to-subsurface communications, and methods of using the system. The system can include one or multiple transmitters comprising electromagnetic beacons, software defined radio receivers with an associated processing unit and data acquisition system, and magnetic antennas. The system may use theoretical calculations, scale model testing, signal processing, and sensor data.

Abstract: In an orthophotograph recorder, a three dimensional optical model of a terrain produced by a stereo pair of aerial transparencies is projected onto an imaging plate. The optical model is scanned by an optically produced reference point while the height of the viewing plate is manually adjusted by the operator to maintain the reference on the apparent ground level of the terrain. The scanning motion of the reference point, as well as the height of the imaging plate, is digitally encoded and formatted into data blocks. Each block of digital data represents an individual scan line on the optical model, and is characterized by a starting coordinate and incremental coordinate data. This data format minimizes storage requirements and permits editing of individual scan lines. The encoded data are scaled and stored on magnetic tape to be used to control exposure of a photosensitive sheet in an orthophotograph printer. The printer comprises a light projector located above a platen carrying the photosensitive sheet.