Angle-of-arrival measurement via spectral estimation of radar time-of-arrival periodicities
First Claim
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1. A method to perform angle-of-arrival measurements (AOA) of radar signals using a first antenna and a second antenna separated by a distance d, wherein Time-Of-Arrival (TOA) values of the radar signals at the first and second antennas have been time tagged using Electronic Warfare (EW) receiver means and a TOA clock having a resolution T;
- the TOA values for the signals from the first and second antennas being represented respectively as
space="preserve" listing-type="equation">TOA.sub.1 (i)=δ
(n.sub.i)
space="preserve" listing-type="equation">TOA.sub.2 (i)=δ
(n.sub.i -mT)where k represents the discrete frequency components, the ni are the individual Time-Of-Arrival (TOA) data values and N is the last TOA value collected, and m =(0,1,2,. . . );
wherein said method comprises;
determining the Pulse Repetition Intervals using a Discrete Fourier Transform (DFT) X1 (k) for signals from the first antenna and X2 (k) for signals from the second antenna as ##EQU8## where k represents the discrete frequency components, the ni are the individual Time-Of-Arrival (TOA) data values and N is the last TOA value collected;
selecting peak values of k corresponding to the peaks of the modulus of the DFTs representing Pulse Repetition Frequency (PRF) for signals from the first and the second antennas;
taking the phase values φ
1 and φ
2 respectively from the DFTs for the signals from the two antennas as ##EQU9## determining the difference between the phase values φ
1 and φ
2 for a peak value of k as ##EQU10## estimating a value for TDOA as;
##EQU11## determining the angle-of-arrival AOA as ##EQU12##
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Abstract
The method provides the capability to estimate the angle-of-arrival (AOA) of radar pulses with respect to a ground or airborne based platform. It utilizes a spectral estimation technique which extracts the periodic properties of radar signals whose time-of-arrivals (TOAs) have been tagged by an Electronic Warfare receiver. The method can be used in a multiple signal environment and can separate and individually measure AOA of emitters that are spatially very close but have incommensurate Pulse Repetition Intervals (PRIs).
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1 Claim
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1. A method to perform angle-of-arrival measurements (AOA) of radar signals using a first antenna and a second antenna separated by a distance d, wherein Time-Of-Arrival (TOA) values of the radar signals at the first and second antennas have been time tagged using Electronic Warfare (EW) receiver means and a TOA clock having a resolution T;
- the TOA values for the signals from the first and second antennas being represented respectively as
space="preserve" listing-type="equation">TOA.sub.1 (i)=δ
(n.sub.i)
space="preserve" listing-type="equation">TOA.sub.2 (i)=δ
(n.sub.i -mT)where k represents the discrete frequency components, the ni are the individual Time-Of-Arrival (TOA) data values and N is the last TOA value collected, and m =(0,1,2,. . . ); wherein said method comprises; determining the Pulse Repetition Intervals using a Discrete Fourier Transform (DFT) X1 (k) for signals from the first antenna and X2 (k) for signals from the second antenna as ##EQU8## where k represents the discrete frequency components, the ni are the individual Time-Of-Arrival (TOA) data values and N is the last TOA value collected; selecting peak values of k corresponding to the peaks of the modulus of the DFTs representing Pulse Repetition Frequency (PRF) for signals from the first and the second antennas; taking the phase values φ
1 and φ
2 respectively from the DFTs for the signals from the two antennas as ##EQU9## determining the difference between the phase values φ
1 and φ
2 for a peak value of k as ##EQU10## estimating a value for TDOA as;
##EQU11## determining the angle-of-arrival AOA as ##EQU12##
- the TOA values for the signals from the first and second antennas being represented respectively as
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Current AssigneeThe United States of America As Represented By The Secretary of Agriculture
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Original AssigneeUnited States Of America As Represented By The Secretary Of The Air Force
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InventorsTsui, James B. Y., Sharpin, David L., Shaw, Rudy L.
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Primary Examiner(s)Sotomayor, John B.
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Application NumberUS08/053,758Time in Patent Office285 DaysField of Search342/424, 342/433, 342/434, 342/156, 342/442, 342/196, 342/13US Class Current342/424CPC Class CodesG01S 7/021 Auxiliary means for detecti...
