US5539408A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the detection, localization and velocity determination of moving targets from raw radar data from a coherent, single- or multi-channel image system carried along in a vehicle
Assignee: Deutsches Zentrum für Luft- und Raumfahrt eV
Abstract In a method for the detection, localization and velocity determination of moving targets from raw radar data from a coherent, single- or multi-channel image system (SAR), for representing the surface of the earth with different backscatter ratios, chronologically successive azimuth spectra are continuously formed during a defined period of time and a frequency shift of the backscatter ratio portion is obtained by determining the position of the maximum of the correlations between respectively two azimuth spectra formed chronologically directly in succession. Then the frequency shifts of the entire raw radar data set are evaluated for producing a frequency shift map. By searching for values deviating from the nominal Doppler rate in the Doppler rate map, a respective moving target is detected and the center of an image of the detected moving target is formed from this. By neglecting its radial acceleration, the tangential velocity of the moving target is determined by means of a Doppler rate taken from the Doppler rate map, and finally the radial velocity of the moving target is determined from the ratio of a length of the moving target in the range direction on the Doppler rate map and the duration of a scanning time by the antenna.
A method for the detection, localization and velocity determination of moving targets from raw radar data from a coherent, single- or multi-channel image system (SAR) carried along in a vehicle, wherein, for representing the surface of the earth with different backscatter ratios, chronologically successive azimuth spectra are continuously formed during a defined period of time and a frequency shift (Delta F(t)) of the backscatter ratio portion is obtained by determining the position of the maximum of the correlations between respectively two azimuth spectra formed chronologically directly in succession, characterized in that the frequency shifts (Delta F(t)) of the entire raw radar data set are evaluated for producing a frequency shift map (Delta (t, r)); a Doppler rate map (D(t, r)) is obtained by dividing the frequency shift map (Delta F(t, r)) by the chronological distance (Delta t) of two azimuth aspects recorded in direct succession, next a respective moving target (B) is detected by searching for values deviating from the nominal Doppler rate (D nom ) in the Doppler rate map (Delta (t, r), the center of an image of the detected moving target (B) is formed in order to localize the moving target (B) in respect to its position in the flight and range direction, by neglecting its radial acceleration, the tangential velocity (v T ) of the moving target is determined by means of a Doppler rate (D mB ) taken from the Doppler rate map (D(t, m)), and finally the radial velocity (v R ) of the moving target (B) is determined from the ratio of a length (r B ) of the moving target in the range direction on the Doppler rate map (Delta (t, r)) and the duration (t B ) of a scanning time by the antenna.
Claim 2
Independent Claim
293 words
A method for the detection, localization and velocity determination of moving targets from raw radar data from a coherent, single- or multi-channel image system (SAR) carried along in a vehicle, wherein, for representing the surface of the earth with different backscatter ratios, chronologically successive azimuth spectra are continuously formed during a defined period of time and a frequency shift (Delta F(t)) of the backscatter ratio portion is obtained by determining the position of the maximum of the correlations between respectively two azimuth spectra formed chronologically directly in succession, characterized in that the frequency shifts (Delta F(t)) of the entire raw radar data set are evaluated for producing a frequency shift map (Delta (t, r)); a Doppler rate map (D(t, r)) is obtained by dividing the frequency shift map (Delta F(t, r)) by the chronological distance (Delta t) of two azimuth aspects recorded in direct succession, next a respective moving target (B) is detected by searching for values deviating from the nominal Doppler rate (D nom ) in the Doppler rate map (Delta (t, r), the center of an image of the detected moving target (B) is formed in order to localize the moving target (B) in respect to its position in the flight and range direction, by neglecting its radial acceleration, the tangential velocity (v T ) of the moving target is determined by means of a Doppler rate (D mB ) taken from the Doppler rate map (D(t, m)), and finally the radial velocity (v R ) of the moving target (B) is determined from the ratio of a length (r B ) of the moving target in the range direction on the Doppler rate map (Delta (t, r)) and the duration (t B ) of a scanning time by the antenna.