Method and apparatus for adaptively determining the bearing angle of a radio frequency signal
First Claim
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1. An apparatus for determining the bearing angle of a radio frequency (RF) signal comprising:
- means for commutating between a plurality of RF signal receiving antenna elements to provide a sampled RF signal, the commutating means providing commutation induced phase and amplitude modulation to the RF signal;
means for modulating the sampled and modulated RF signal to an intermediate frequency (IF) signal, the IF signal including the commutation induced phase and amplitude modulation;
means for detecting the IF signal;
means for filtering the IF signal and providing detected frequency modulation (FM), amplitude modulation (AM), single sideband (SSB) and pulsed signals; and
means responsive to the detecting means for removing the commutation induced phase and amplitude modulation from the IF signal whereby the bearing angle of the RF signal is determined.
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Abstract
A system and method for obtaining the bearing angle of radio frequency is utilized in a direction finding system to determine the signal of interest. The system utilized an adaptive interferometric processor to null out modulation occurring due to commutation between the antenna elements. Through this system the bearing angle can be determined accurately and efficiently.
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Citations
18 Claims
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1. An apparatus for determining the bearing angle of a radio frequency (RF) signal comprising:
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means for commutating between a plurality of RF signal receiving antenna elements to provide a sampled RF signal, the commutating means providing commutation induced phase and amplitude modulation to the RF signal; means for modulating the sampled and modulated RF signal to an intermediate frequency (IF) signal, the IF signal including the commutation induced phase and amplitude modulation; means for detecting the IF signal; means for filtering the IF signal and providing detected frequency modulation (FM), amplitude modulation (AM), single sideband (SSB) and pulsed signals; and means responsive to the detecting means for removing the commutation induced phase and amplitude modulation from the IF signal whereby the bearing angle of the RF signal is determined. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for determining the bearing angle of a radio frequency (RF) signal comprising:
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a switch for commutating between a plurality of RF signal receiving antenna elements to provide a sampled RF signal, the switch providing commutation induced phase and amplitude modulation to the RF signal; a vector modulation for modulating the sampled and modulated RF signal to an intermediate frequency (IF) signal, the IF signal including the commutation induced modulation; means for detecting the IF signal; narrowband filter for filtering the IF signal and providing selected frequency modulation (FM), amplitude modulation (AM), single sideband (SSB) and pulsed signals; and a processor responsive to the detecting means for adaptively removing the commutation induced phase and amplitude modulation from the IF signal whereby the bearing angle of the RF signal is determined. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method for determining the bearing angle of a radio frequency (RF) signal comprising the steps of:
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(a) commutating between a plurality of RF signal receiving antenna elements to provide a sampled RF signal, and to provide commutation induced phase and amplitude modulation to the RF signal; (b) converting the sampled and modulated RF signal to an intermediate frequency (IF) signal, the IF signal including the commutation induced modulation; (c) detecting the IF signal; (d) removing the commutation induced phase and amplitude modulation from the IF signal whereby the bearing angle of the RF signal is determined and (e) filtering the IF signal and providing selected frequency modulation (FM), amplitude modulation (AM), single sideband (SSB) and pulsed signals. - View Dependent Claims (15, 16, 17)
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18. A method for adaptively determining the bearing angle of RF signal utilizing a plurality of antenna elements comprising the steps of:
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(a) initializing each of the antenna elements; (b) switching between each of the plurality of antenna elements to sample an output signal from each of the plurality of antenna elements; (c) measuring the output signal for phase and amplitude from each of the plurality of antenna elements to provide an impulse transient from each of the antenna elements; (d) computing an average of the measurements from step (c) of the impulse transients from the plurality of antenna elements; (e) removing a bias term from the average of the measurements; and (f) computing the bearing angle from the results of steps (a)-(e).
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Specification