Method and apparatus for multiple reply rejection when decoding transponder replay signals
First Claim
1. A method for rejecting multiple reply signals received from a target transponder within a selectable time period, comprising the steps of:
- a. determining an angle of arrival (AOA) value for each reply signal using an antenna that produces, in response to said reply signals, phase related signals corresponding to target bearing;
b. determining an altitude code associated with each reply signal;
c. determining a differential time of arrival (DTA) value for each reply signal based on the difference between the time the reply signal was received and a predetermined reference time;
d. producing, for each reply signal, a target report that includes said altitude code, AOA and DTA values; and
e. comparing said altitude code, AOA and DTA data of an anchor target report with other target reports for matching, within defined limits, corresponding data of each other target report and said anchor target report to identify matched target reports and marking out such matched target reports as multiple replies from the target corresponding to the anchor target report.
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Accused Products
Abstract
Apparatus for rejecting multipath reply signals received from a target transponder within a selectable time period, comprising: a top antenna and a bottom antenna to detect reply signals; means for determining an altitude code associated with each reply signal detected by the antennas respectively; means for determining a differential time of arrival (DTA) value for each reply signal detected by the antennas respectively; and processing means for: 1) producing, for each top antenna reply signal, a top antenna target report that includes the altitude code and DTA values; 2) producing for each bottom antenna reply signal, a bottom antenna target report that includes the altitude code and DTA data; and 3) comparing each top antenna report data with corresponding data from each bottom antenna report, and marking out each bottom antenna report that is a multipath reply based on such comparison.
30 Citations
22 Claims
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1. A method for rejecting multiple reply signals received from a target transponder within a selectable time period, comprising the steps of:
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a. determining an angle of arrival (AOA) value for each reply signal using an antenna that produces, in response to said reply signals, phase related signals corresponding to target bearing; b. determining an altitude code associated with each reply signal; c. determining a differential time of arrival (DTA) value for each reply signal based on the difference between the time the reply signal was received and a predetermined reference time; d. producing, for each reply signal, a target report that includes said altitude code, AOA and DTA values; and e. comparing said altitude code, AOA and DTA data of an anchor target report with other target reports for matching, within defined limits, corresponding data of each other target report and said anchor target report to identify matched target reports and marking out such matched target reports as multiple replies from the target corresponding to the anchor target report. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for rejecting multipath reply signals received from a target transponder within a selectable time period, comprising the steps of:
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a. using a top antenna and a bottom antenna to detect reply signals; b. determining an altitude code associated with each reply signal detected by said antennas; c. determining a differential time of arrival (DTA) value for each reply signal detected by said antennas; d. producing, for each top antenna reply signal, a top antenna target report that includes said altitude code and DTA values, and producing for each bottom antenna reply signal, a bottom antenna target report that includes said altitude code and DTA data; and e. comparing each top antenna target report data with corresponding data from each bottom antenna target report, and marking out each bottom antenna target report whose altitude code and DTA value are matched to the corresponding altitude code and DTA value of a top antenna target report based on a predetermined matching criteria. - View Dependent Claims (13)
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14. Apparatus for rejecting multiple reply signals received from a target transponder within a selectable time period, comprising:
- antenna means for receiving the reply signals and producing phase related signals corresponding to target bearing;
means for determining an angle of arrival (AOA) value for each reply signal corresponding to target bearing;
means for determining an altitude code associated with each reply signal;
means for determining a differential time of arrival (DTA) value for each reply signal based on the difference between the time the reply signal was received and a predetermined reference time; and
processing means for;
1) producing, for each reply signal, a target report that includes said altitude code, AOA and DTA values; and
2) comparing said altitude code, AOA and DTA data of an anchor target report with other target reports for matching, within defined limits, corresponding data of each other target report and said anchor target report to identify matched target reports, and marking out such matched target reports as multiple replies from the target corresponding to the anchor target report. - View Dependent Claims (15, 16)
- antenna means for receiving the reply signals and producing phase related signals corresponding to target bearing;
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17. Apparatus for rejecting multipath reply signals received from a transponder of a mobile target within a selectable time period, comprising:
- a top antenna and a bottom antenna to detect reply signals;
means for determining an altitude code associated with each reply signal detected by said antennas respectively;
means for determining a differential time of arrival (DTA) value for each reply signal detected by said antennas respectively; and
processing means for;
1) producing, for each top antenna reply signal, a top antenna target report that includes said altitude code and DTA values;
2) producing for each bottom antenna reply signal, a bottom antenna target report that includes said altitude code and DTA data; and
3) comparing each top antenna target report altitude code and DTA data with corresponding altitude code and DTA data from each bottom antenna target report, and marking out each bottom antenna target report that is identified as a multipath reply based on such comparison. - View Dependent Claims (18)
- a top antenna and a bottom antenna to detect reply signals;
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19. A method for rejecting multiple reply signals received from a transponder of a mobile target within a selectable time period, comprising the steps of:
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a. determining an altitude code associated with each reply signal; b. determining a differential time of arrival (DTA) value for each reply signal; c. producing a target report for each reply signal which report includes said altitude code and DTA value; and d. comparing said altitude code and DTA value of each target report for matching, within defined limits, corresponding data of each other target report, and marking out target reports that identified as are multiple replies from the mobile target based on said comparisons. - View Dependent Claims (20)
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21. Apparatus for rejecting multiple reply signals received from a transponder of a mobile target within a selectable time period comprising:
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means for determining an altitude code for each reply signal; means for determining a differential time of arrival (DTA) value for each reply signal; and processing means for identifying multiple reply signals of said mobile target based on a comparison of said altitude code and DTA data for each reply signal with respect to each other reply signal.
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22. A method for rejecting multipath reply signals received from a transponder of a mobile target within a selectable time period, comprising the steps of:
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a. using a top and bottom antenna to detect reply signals; b. determining an altitude code for each reply signal; c. determining a differential time of arrival (DTA) value for each reply signal; and d. comparing the altitude code and DTA value of reply signals detected by the top antenna to the altitude code and DTA value of reply signals detected by the bottom antenna and identifying multipath bottom antenna detected reply signals based on matching criteria for the corresponding altitude codes and DTA values.
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Specification