A collision avoidance system for sea navigation comprises, for each equipped ship, a transmitter that repeatedly transmits the geographic coordinates, course and speed of its own ship and a receiver that sends a display device similar data received from other ships. These received data are displayed, mostly in the form of symbols, on the panoramic screen of the display device.

A radio direction finding system comprises a receiving portion for receiving a radio signal and a direction determining portion coupled to the receiving portion for developing a direction signal corresponding to the direction of arrival of a received radio signal. A memory is also provided for storing direction data corresponding to the direction of arrival of at least one received radio signal, and a control circuit is coupled intermediate the direction determining portion and the memory for producing direction data corresponding to the direction signal for storage by said memory. In accordance with a further aspect of the invention, an indicator is provided for actuation by the control circuit to produce an observable indication of the direction of arrival of a received radio signal, and the direction finding system further includes an EPIRB detector portion for producing an EPIRB reception signal in response to reception of an EPIRB signal. The control circuit is responsive to the EPIRB detection signal for energizing an indicator to produce an indication of the direction of arrival of the EPIRB signal in place of any other indication of direction.

The present invention relates to a method and device for providing a graphical user interface between an individual soldier and a computer-based warfare system worn by him. The graphical user interface is made up of icon-based visual control and information screens that the soldier views on a display and manipulates with a computer mouse-like device. The interface allows the individual soldier to: view information gathered by a variety of sources, including sensor components, radios, and satellites; process information using a variety of input devices and software utilities; and, act on that information using weapons, communications devices, and the like. The graphical user interface organizes information into three distinct "combat task" groups and provides the soldier with easily understood pictorial icons to select. By tailoring the information to a particular situation, the graphical user interface allows the soldier to view critical data without being overwhelmed by too much information.

Systems and methods that add motion lines that indicate motion in a still image include selecting two or more video fields or frames, compensating for global motion in the selected fields or frames, determining the difference between positions of pixels in the selected fields or frames, identifying regions of motion with pixels having a difference that is greater than a threshold value, identifying points of interest in the regions of motion, selecting pixels from the points of interest, determining the motion of the selected points of interest, and adding lines to the still image that extend from the selected pixels.

A moving target discriminator uses only bearing information obtained from passive observations together with information about the movement of an observation platform to discriminate whether an object is moving. An underlying principle of the moving target discriminator is that the intercepts of successive line-of-sight observations taken from the moving platform will move only if the object is moving. In a specific embodiment, three line-of-sight observations are made, and an intercept is computed for two different pairs of observations. If the intercepts coincide, the cited object is classified as stationary otherwise, it is classified as moving. Measurement statistics are used to compensate the computed intercepts for navigational and observation errors.