Abstract

Disclosed is a navigational system for accurately determining the position of a vehicle, such as a boat, truck, automobile or airplane in relation to two or more commercial AM radio transmission antenna or other signal sources of known longitude and latitude. The frequencies and exact coordinates (longitude and latitude) of the radio antenna are entered by keyboard input into the memory of the system. The null angles from the vehicle to the radio antenna are determined automatically by a computer controlled radio direction finder antenna mounted on the vehicle. The heading of the vehicle is determined and the relative null angles (in relation to the heading of the vehicle) are converted to standard null headings (North, 0°) by the system. The known positions of the stations are automatically compared by the system to the respective true and false (180° opposite) null headings and the correct angles are selected according to the proper trigonometric relationship (the sum of the internal angles of a triangle must equal 180°). Once the system has selected the proper null headings, the exact position of the vehicle can then be determined automatically and the coordinates displayed on a visual display. The system can also be adapted to allow input of one or more sets of destinational or navigational coordinates and the system will display the correct compass heading to be steered to reach the selected coordinates. The coordinates of hazards can also be entered and the system will provide a warning if the vehicle comes too close to the hazards.

Other References

• Landfall A High-Resolution Automatic Vehicle-Location System; D. King, GEC Journal of Science & Technology, vol. 45, No. 1, 1978, pp. 34-44