Signal acquisition and tracking system
First Claim
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1. A circuit for use in a signal acquisition and tracking system in a known frequency range with a signal of known modulation characteristics comprising:
- means for receiving electromagnetic signals originating omnidirectionally in azimuth with respect to a predetermined location and from within a narrow beam width which is of variable elevation;
a tuning network varying the frequency received over said frequency range operably connected to said receiving means; and
means for controlling the variation in elevation of said receiving means sensitivity and for simultaneously and selectively controlling the frequency variation accomplished by said tuning network, operably connected to said receiving means and said tuning network.
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Abstract
Microprocessor controlled electronically scanned collinear array receiver stem includes a dipole antenna mounted atop the array to provide complete scan coverage from horizon to horizon. The microprocessor controls the scan angle and the frequency range to provide full search coverage for all scan angles in a hemisphere. Simultaneous angle tracking and frequency tracking are accomplished when the desired signal is acquired.
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Citations
18 Claims
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1. A circuit for use in a signal acquisition and tracking system in a known frequency range with a signal of known modulation characteristics comprising:
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means for receiving electromagnetic signals originating omnidirectionally in azimuth with respect to a predetermined location and from within a narrow beam width which is of variable elevation; a tuning network varying the frequency received over said frequency range operably connected to said receiving means; and means for controlling the variation in elevation of said receiving means sensitivity and for simultaneously and selectively controlling the frequency variation accomplished by said tuning network, operably connected to said receiving means and said tuning network. - View Dependent Claims (6, 7, 8, 9)
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2. A circuit according to claim one wherein said receiving means comprises:
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a vertically oriented array of bicone elements; a base upon which said array is mounted; an electronics chassis in said base; a corporate radio frequency feed network mounted in said chassis; a plurality of phase shifters operably connected to said feed network; coaxial cables, each connecting an individual array element and a phase shifter, said cables being routed through the center of said array; means for searching for overhead signals, mounted atop said array; a switch connected to said radio frequency feed network for selecting reception via said array or said searching means; and a coaxial cable, routed through the center of said array connecting said selector switch and said searching means. - View Dependent Claims (3, 4, 5)
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10. A method of signal acquisition and tracking utilizing a microprocessor controlled electrically scanned antenna and receiver system comprising the steps of:
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searching a frequency range while varying the antenna pattern elevation in excess of 90°
;validating any signal received from said search; and tracking said validated signal. - View Dependent Claims (11, 12, 13, 14, 16, 17)
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15. A method of signal acquisition and tracking utilizing a microprocessor controllable electrically scanned antenna/receiver unit and a signal in a known frequency range and modulation format comprising the steps of:
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producing an antenna pattern that is omnidirectional in azimuth and directional in elevation; varying the frequency received across the frequency range to be searched while holding the elevation of the antenna pattern constant; increasing the elevation of the pattern one beam width when said varying step has been completed; repeating said varying and increasing steps to search for the desired frequency from sub-horizon elevation to +60°
of elevation in elevation increments equivalent to one band width;producing an omnidirectional antenna pattern above +60°
of elevation;tuning said receiver across the frequency range to be searched while the antenna pattern is above +60°
elevation;providing said microprocessor with reference information as to said desired signal'"'"'s modulation format; comparing any received signal with said reference; angle tracking any signal which by comparison matches the reference for as long as the signal is present; frequency tracking said matched signal concurrently with said angle tracking; and extracting data from said tracked signal.
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18. An antenna system for use with a microprocessor as a scan controller, having a radiation pattern that is omnidirectional in azimuth and directed in elevation comprising:
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a base; an array of bicone elements vertically mounted on said base; a plurality of coaxial cables, each connected to a bicone element and running down the central axis of said array; a plurality of phase shifters, each connected to one of said coaxial cables, and mounted in said base; a cylindrical radome which also serves as a polarizer mounted about said array and fastened to said base; a crossed dipole antenna mounted above said array and fastened to the top of said cylindrical radome; a hemispherical radome covering said dipole and fastened to said cylindrical radome; a switch for choosing either said array or said dipole as the active antenna; a coaxial cable connecting said switch and said dipole; a chassis mounted within said base, an RF feed network marked as said chassis and connected to said phase shifter; scan electronics connected to phase shifter and having an input from said microprocessor.
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Specification