TECHNIQUE FOR MITIGATING MULTIPATH IMPACTS ON AZIMUTH ACCURACY IN A MONOPULSE INTERROGATOR
First Claim
1. A method for mitigating multipath impacts on azimuth accuracy in a monopulse interrogator the steps of the method comprising:
- calculating samples of monopulse ratio for samples of antenna boresight angle using interrogation replies from a target;
calculating samples of traditional target azimuth from the samples of monopulse ratio;
calculating a mean of the samples of traditional target azimuth;
calculating a standard deviation of the samples of traditional target azimuth from the samples of monopulse ratio; and
comparing the standard deviation to a predetermined threshold to determine if a multipath signal exists.
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Abstract
A method for mitigating multipath impacts on azimuth accuracy in a monopulse interrogator is accomplished by calculating samples of monopulse ratio for samples of antenna boresight angles based on data received from an interrogation of a target. Samples of traditional target azimuth from the samples of monopulse ratio are calculated. A mean of the samples of traditional target azimuth is calculated. An alternative target azimuth from the samples of monopulse ratio is calculated. Whether a multipath signal exists is determined from observing a standard deviation of the samples of traditional target azimuth, and using the mean of the traditional target azimuth if a multipath signal does not exist and using the alternative target azimuth if a multipath signal does exist.
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Citations
25 Claims
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1. A method for mitigating multipath impacts on azimuth accuracy in a monopulse interrogator the steps of the method comprising:
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calculating samples of monopulse ratio for samples of antenna boresight angle using interrogation replies from a target; calculating samples of traditional target azimuth from the samples of monopulse ratio; calculating a mean of the samples of traditional target azimuth; calculating a standard deviation of the samples of traditional target azimuth from the samples of monopulse ratio; and comparing the standard deviation to a predetermined threshold to determine if a multipath signal exists. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for mitigating multipath impacts on azimuth accuracy in a monopulse interrogator, the steps of the method comprising:
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calculating samples of monopulse ratio for samples of antenna boresight angle using interrogation replies from a target; calculating a magnitude for each of the samples of the monopulse ratio; calculating a quadrature angle for each of the samples of the monopulse ratio; calculating a magnitude for each quadrature angle for each of the samples of the monopulse ratio; calculating a real part for each of the samples of the monopulse ratio; calculating samples of traditional target azimuth from the samples of monopulse ratio; calculating a mean of the samples of traditional target azimuth;
calculating a standard deviation of the samples of traditional target azimuth;comparing the standard deviation to a predetermined threshold to determine if a multipath signal exists, the multipath signal does exist if the standard deviation is above a predetermined value and the multipath signal does not exist if the standard deviation is not above a predetermined value; and outputting the mean of the samples of traditional target azimuth if the multipath signal does not exist and outputting the alternative target azimuth if the multipath signal does exist. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for mitigating multipath impacts on azimuth accuracy in a monopulse interrogator the steps of the method comprising:
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calculating samples of monopulse ratio for samples of antenna boresight angles from an interrogation of a target; calculating a magnitude for each of the samples of the monopulse ratio; calculating a quadrature angle for each of the samples of the monopulse ratio; calculating a real part for each of the samples of the monopulse ratio; calculating samples of traditional target azimuth from the samples of monopulse ratio; calculating a mean of the samples of traditional target azimuth; searching for antenna boresight angles at which one or more minima of the magnitudes of the samples of monopulse ratio occur; searching for antenna boresight angles at which one or more maxima of the magnitudes of the samples of quadrature angles occur; determining a target azimuth region using the one or more minima of the magnitudes of the samples of monopulse ratio and the one or more maxima of the magnitudes of the samples of quadrature angle; calculating an alternative target azimuth from the samples of monopulse ratio within the target azimuth region; comparing the standard deviation to a predetermined threshold to determine if a multipath signal exists, wherein the multipath signal does exist if the standard deviation is above a predetermined threshold value and the multipath signal does not exist if the standard deviation is not above a predetermined threshold value; and outputting the mean of the samples of traditional target azimuth if the multipath signal does not exist and outputting the alternative target azimuth if the multipath signal does exist. - View Dependent Claims (16, 17)
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18. A monopulse interrogator comprising:
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an antenna for interrogating a target and receiving data from the target; a monopulse ratio calculation module connected to the antenna for receiving the target data and calculating samples of monopulse ratio for samples of antenna boresight angles using the samples of data; a traditional target azimuth calculation module connected to the monopulse ratio calculation module for receiving the samples of monopulse ratio and calculating a mean of traditional target azimuths using the samples of monopulse ratio; an alternative target azimuth calculation module connected to the monopulse ratio calculation module for receiving the samples of monopulse ratio and calculating a second target azimuth using the samples of monopulse ratio; and an azimuth selection module connected to the traditional target azimuth calculation module for receiving the mean of the traditional target azimuth and connected to the alternative target azimuth calculation means for receiving the alternative target azimuth, the azimuth selection module selecting the mean of the traditional target azimuths if multipath signals do not exist, or the alternative target azimuth if multipath signals exist. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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Specification