Adaptive radio direction finding system
First Claim
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1. A radio direction finding system for determining the direction of radio frequency signal transmissions with respect to a receiving location, comprising:
- an antenna which performs 360°
sweeps for receiving radio frequency signals from sources of radio frequency signal transmissions;
receiver means coupled to said antenna and responsive to said received radio frequency signals for producing a plurality of output signals, each one of said plurality of output signals corresponding to said received radio frequency signals, said output signals containing information indicative of the signal strength and bearing of said received radio frequency signals;
means responsive to said output signals for extracting said signal strength and bearing information and for providing corresponding signal strength signals and bearing signals indicative thereof;
characterized by;
means responsive to said signal strength signals and said bearing signals for determining if the magnitude of said signal strength signals are greater than a threshold magnitude, and for determining that a source of radio frequency signal transmissions is present at a bearing if signal strength signals of a magnitude greater than said threshold magnitude are present at a corresponding bearing for a statistically significant number of antenna sweeps.
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Abstract
RF energy received by an antenna (10) of a radio direction finding system is evaluated for determining the presence of a RF signal transmission source at bearing values at which the received RF energy is statistically strong (33) and which have a relatively stable signal strength (35). The scanning pattern (sequence) ( 12, 15) of the antennae is altered to increase the dwell time of the antennae at bearings having a statistically strong and relatively stable signal strength combination, and decrease the percentage of time spent scanning the remainder of the 360 degree search spectrum. External sensors (30) are used to sense changes in antennae orientation with respect to a fixed reference to thereby reduce bearing errors (27) during changes in the attitude and heading of the platform carrying the radio direction finding system.
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Citations
31 Claims
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1. A radio direction finding system for determining the direction of radio frequency signal transmissions with respect to a receiving location, comprising:
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an antenna which performs 360°
sweeps for receiving radio frequency signals from sources of radio frequency signal transmissions;receiver means coupled to said antenna and responsive to said received radio frequency signals for producing a plurality of output signals, each one of said plurality of output signals corresponding to said received radio frequency signals, said output signals containing information indicative of the signal strength and bearing of said received radio frequency signals; means responsive to said output signals for extracting said signal strength and bearing information and for providing corresponding signal strength signals and bearing signals indicative thereof; characterized by; means responsive to said signal strength signals and said bearing signals for determining if the magnitude of said signal strength signals are greater than a threshold magnitude, and for determining that a source of radio frequency signal transmissions is present at a bearing if signal strength signals of a magnitude greater than said threshold magnitude are present at a corresponding bearing for a statistically significant number of antenna sweeps. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method for determining the direction of radio frequency signal transmissions with respect to a receiving location, comprising the steps of:
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performing 360°
sweeps with an antenna for receiving radio frequency signals from sources of radio frequency signal transmissions;providing output signals corresponding to radio frequency signals received during said 360°
sweeps, said output signals containing information indicative of the signal strength and bearing of said received radio frequency signals;extracting said signal strength and beating information from said output signals and providing corresponding signals strength signals and bearing signals indicative thereof; determining if the magnitude of said signal strength signals are greater than a threshold magnitude; and identifying a source of radio frequency signal transmissions at a beating if signal strength signals of a magnitude greater than a threshold magnitude are present at a corresponding bearing for a statistically significant number of antenna sweeps. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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Specification
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Current AssigneeUnited Technologies Corporation (Rtx Corporation)
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Original AssigneeUnited Technologies Corporation (Rtx Corporation)
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InventorsAnttila, Donald S.
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Primary Examiner(s)Blum, Theodore M.
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Application NumberUS08/156,124Time in Patent Office652 DaysField of Search342/400, 342/449US Class Current342/400CPC Class CodesG01S 3/20 derived by sampling signal ...
