System and method for providing timing services and DME aided multilateration for ground surveillance
First Claim
1. A method DME aided multilateration, the method comprising:
- transmitting interrogation pulses from at least one DME interrogator that are received by at least one DME transponder;
transmitting reply pulses from at least one DME transponder in response to the interrogation pulses received from the at least one DME interrogator;
providing at least one DME listener forreceiving and demodulating the interrogation pulses transmitted by the at least one DME interrogator and the reply pulses transmitted by the at least one DME transponder,cross correlating the received interrogation pulses and reply pulses and determining a cross correlation output;
determining an interrogation pattern of the received interrogation pulses and reply pulses by selecting overlapping pulses of the received interrogation pulses and reply pulses when a maximum peak for cross correlation occurs in the cross correlation output,determining a time difference of arrival (TDOA) for the associated interrogation pulses and reply pulses using the position of the maximum peak of cross correlation, known time delay of the DME transponder and known distance between the at least one DME transponder and the at least DME listener,transmitting at least the determined TDOA, interrogation pattern information, and the ID of the DME listener to a central computer;
wherein the central computerreceives at least the determined TDOA interrogation pattern information, and DME listener ID from the at least one DME listener,associates the determined TDOA to a specific transmission of interrogation pulses from the at least one DME interrogator using the interrogation pattern information to form a DOA cluster, anddetermines a position for the at least one DME interrogator when three or more TDOAs are clustered.
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Accused Products
Abstract
The present invention utilizes the existing DME transponder system infrastructure to augment existing ground surveillance multilateration (MLAT) capabilities by providing additional measurements for determining the position of an aircraft equipped with a DME transponder. DME listeners receive DME interrogation signals and DME reply signals, determine TDOA between the DME transponder and each DME listener, and transmit data to a central computer that clusters TDOAs between the DME transponder and the DME listeners and computes the aircraft position using the clustered TDOAs. The DME-aided MLAT can be used as a backup surveillance system when GNSS-based systems are unavailable. The DME-aided MLAT can be integrated with SSR receive units (RUs) performing multilateration (MLAT) calculations.
31 Citations
27 Claims
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1. A method DME aided multilateration, the method comprising:
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transmitting interrogation pulses from at least one DME interrogator that are received by at least one DME transponder; transmitting reply pulses from at least one DME transponder in response to the interrogation pulses received from the at least one DME interrogator; providing at least one DME listener for receiving and demodulating the interrogation pulses transmitted by the at least one DME interrogator and the reply pulses transmitted by the at least one DME transponder, cross correlating the received interrogation pulses and reply pulses and determining a cross correlation output; determining an interrogation pattern of the received interrogation pulses and reply pulses by selecting overlapping pulses of the received interrogation pulses and reply pulses when a maximum peak for cross correlation occurs in the cross correlation output, determining a time difference of arrival (TDOA) for the associated interrogation pulses and reply pulses using the position of the maximum peak of cross correlation, known time delay of the DME transponder and known distance between the at least one DME transponder and the at least DME listener, transmitting at least the determined TDOA, interrogation pattern information, and the ID of the DME listener to a central computer; wherein the central computer receives at least the determined TDOA interrogation pattern information, and DME listener ID from the at least one DME listener, associates the determined TDOA to a specific transmission of interrogation pulses from the at least one DME interrogator using the interrogation pattern information to form a DOA cluster, and determines a position for the at least one DME interrogator when three or more TDOAs are clustered. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method DME aided multilateration, the method comprising:
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transmitting interrogation pulses from at least one DME interrogator that are received by at least one DME transponder; transmitting reply pulses from at least one DME transponder in response to the interrogation pulses received from the at least one DME interrogator; providing at least one DME listener for receiving and demodulating the interrogation pulses transmitted by the at least one DME interrogator and the reply pulses transmitted by the at least one DME transponder, cross correlating the received interrogation pulses and reply pulses and determining a cross correlation output; determining an interrogation pattern of the received interrogation pulses and reply pulses by selecting overlapping pulses of the received interrogation pulses and reply pulses when a maximum peak for cross correlation occurs in the cross correlation output, determining a time difference of arrival (TDOA) for the associated interrogation pulses and reply pulses using the position of the maximum peak of cross correlation, known time delay of the DME transponder and known distance between the at least one DME transponder and the at least one DME listener, transmitting at least the determined TDOA, interrogation pattern information, and the ID of the DME listener to a central computer; wherein the central computer receives at least the determined TDOA interrogation pattern information, and DME listener ID from the at least one DME listener, associates the determined TDOA to a specific transmission of interrogation pulses from the at least one DME interrogator using the interrogation pattern information to form a TDOA cluster, determines Mode C information for the DME interrogator from another source, and when two or more TDOAs are clustered, determines a position for the DME interrogator from the two TDOAs and the Mode C information. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for DME aided multilateration, the method comprising:
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transmitting interrogation pulses from at least one DME interrogator that are received by at least one DME transponder; transmitting reply pulses from at least one DME transponder in response to the interrogation pulses received from the at least one DME interrogator; providing at least two DME listeners for receiving and demodulating the interrogation pulses transmitted by the at least one DME interrogator and the reply pulses transmitted by the at least one DME transponder, determining a time of arrival (TOA) of each pulse pair in the received interrogation pulses and reply pulses and a received signal strength (RSS) for the received interrogation pulses and reply pulses at each of the at least two DME listeners, and transmitting at least the determined TOA of each pulse pair and RSS for the received interrogation pulses and reply pulses and the ID of the DME listener from each of the at least two DME listeners to a central computer; wherein the central computer receives at least the determined TOA of each pulse pair and RSS for the received interrogation pulses and reply pulses and DME listener ID from each of the at least two DME listeners, associates the received interrogation pulses and reply pulses using the received TOA of each pulse pair and RSS, derives TDOAs between each DME listener of the at least two DME listeners and the at least one DME transponder from the received TOA of each pulse pair and RSS of associated interrogation pulses and reply pulses and the known distance between each DME listener of the at least two DME listeners and the at least one DME transponder, clusters the derived TDOAs to a specific transmission of interrogation pulses from the at least one DME interrogator, and determines a position for the at least one DME interrogator when three or more TDOAs are clustered. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A method for DME aided multilateration, the method comprising:
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transmitting interrogation pulses from at least one DME interrogator that are received by at least one DME transponder; transmitting reply pulses from at least one DME transponder in response to the interrogation pulses received from the at least one DME interrogator; providing at least two DME listeners for receiving and demodulating the interrogation pulses transmitted by the at least one DME interrogator and the reply pulses transmitted by the at least one DME transponder, determining a time of arrival (TOA) of each pulse pair and a received signal strength (RSS) for the received DME interrogation pulses and reply pulses at each of the at least two DME listeners, and transmitting at least the determined TOA of each pulse pair and RSS for the received interrogation pulses and reply pulses and the ID of the DME listener from each of the at least two DME listeners to a central computer; wherein the central computer receives at least the determined TOA of each pulse pair and RSS for the received interrogation pulses and reply pulses and DME listener ID from each of the at least two DME listeners, associates the received interrogation pulses and reply pulses using the received TOA of each pulse pair and RSS, derives TDOA between each of the at least two DME listeners and the at least one DME transponder from the received TOA of each pulse pair and RSS of associated interrogation pulses and reply pulses and the known distance between each of the at least two DME listeners and the at least one DME transponder, clusters the derived TDOAs to a specific transmission of interrogation pulses from the at least one DME interrogator, and determines Mode C information for the DME interrogator from another source; and when two or more TDOAs are clustered, determines a position for the DME interrogator from the two TDOAs and the Mode C information. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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Specification