US 5,396,250 A · Spectral estimation of radar time-of-arrival periodicities

Abstract

Disclosed is a method to extract the periodic properties (or Pulse Repetition Intervals (PRIs)) of radar signals whose time-of-arrival at an airborne platform have been time tagged by an Electronic Warfare (EW) receiver. The PRIs are determined using a modified Discrete Fourier Transform (DFT) written as ##EQU1## where k represents the frequency components, the T.sub.i are the individual Time-Of-Arrival (TOA) data values and N is the last TOA value collected. Disclosed are three possible methods of reducing the number of computations involved with the modification of the Discrete Fourier Transform (DFT) equation to facilitate its use with Radar Time-Of-Arrival (TOA) to extract periodic properties of radar signals. This is particularly applicable to radar pulse trains which are interleaved in time and where each individual pulse train may be staggered or jittered in time so that a time domain deinterleaving scheme must be employed. A spectral estimator can be computed by taking the modulus of the DFT of the time series data and extending the periodogram estimator by making a slight modification of the DFT equation.

Claims8

Dependent claims

Apparatus to extract the Pulse Repetition Intervals (PRIs) of radar signals comprising a train of radar pulses, wherein said apparatus comprises:

an Electronic Warfare (EW) receiver at an airborne platform which includes means for receiving said radar signals and time tagging the time-of-arrival (TOA) of each radar pulse as a time data value.
a memory in which is stored M values of a quantity .sub.R(k)=e -j2.pi.k/N for values of k from 0 to (N-1) inclusive;
where k represents the frequency components, the T.sub.i are the individual time-of-arrival (TOA) data values and N is the last TOA value collected;
and
math means having inputs from the memory supplying said M values and input of the time date values from said Electronic Warfare receiver effective for each time data value T.sub.i for performing the operation ##EQU7## on each of the M values R(k) from the memory and supplying the M results to M summing means respectively;
wherein the M summing means include means to accumulate the values of R(k) for all values of T.sub.i in the train of radar pulses, and to supply the resulting M values to further processing means;
wherein the further processing means includes to determine the Pulse Repetition Intervals using a Discrete Fourier Transform (DFT) equation written as ##EQU8##

4 more elements

A method to extract the Pulse Repetition Intervals (PRIs) of radar signals comprising a train of radar pulses, wherein said method comprises:

using an Electronic Warfare (EW) receiver at an airborne platform for receiving said radar signals and time tagging the time-of-arrival (TOA) of each radar pulse as a time data value;
storing in a memory M values of a quantity .sub.R(k)=e -j2.pi.k/N for values of k from 0 to (N-1) inclusive;
where k represents the frequency components, the T.sub.i are the individual time-of-arrival (TOA) data values and N is the last TOA value collected;
using inputs from the memory supplying said M values and input of the time data values from said Electronic Warfare receiver effective for each time data value T.sub.i and performing the operation ##EQU9## on each of the M values R(k) from the memory and supplying the M results to M summing means respectively;
and
using the M summing means to accumulate the values of R(k) for all values of T.sub.i in the train of radar pulses, and supplying the resulting M values to further processing means;
wherein in the further processing means the Pulse Repetition Intervals are determined using a Discrete Fourier Transform (DFT) equation written as ##EQU10##

4 more elements

Dependencies are inferred from the claim text.

Spectral estimation of radar time-of-arrival periodicities

Life of this patent

Spectral estimation of radar time-of-arrival periodicities

Life of this patent

Abstract

Claims8