Method of synchronizing navigation measurement data with S.A.R radar data, and device for executing this method
First Claim
1. A method of correcting imaging signals generated from a wave unit mounted on a moving platform, whereinthe platform includes a navigational system outputting a navigational deviation signal Δ
- rNAV (t) indicative of deviations from a smooth platform motion;
the wave unit outputs a wave deviation signal Δ
rRDM (t) indicative of the deviations from the smooth platform motion;
the method comprising;
deviation cross-correlating the navigational deviation signal Δ
rNAV (t) and the wave deviation signal Δ
rRDM (t) to obtain a cross-correlation result K(t);
determining a maximum of the resulting cross-correlation result K(t) as a function of time;
setting the cross-correlation result K(t) equal to a time offset Δ
t; and
delaying the wave data by the time offset Δ
t prior to any image generation.
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Abstract
In a method of synchronizing navigation measurement data according to the invention, first radar data are evaluated by means of the reflectivity-offset method, by means of which the aircraft deviation in the antenna viewing direction is determined. The aircraft deviation in this direction is also determined from the outputs of a navigation system. The temporal courses of the two obtained deviations are cross-correlated. The position of the cross-correlation maximum is determined, and indicates the temporal offset between two associated deviation signals. The radar data are delayed by this amount of time, so synchronization is effected between navigation measurement data and radar data. An optimum compensation of the motion errors can be effected with the synchronized data. The invention can be used in on-board aircraft SAR systems.
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Citations
19 Claims
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1. A method of correcting imaging signals generated from a wave unit mounted on a moving platform, wherein
the platform includes a navigational system outputting a navigational deviation signal Δ - rNAV (t) indicative of deviations from a smooth platform motion;
the wave unit outputs a wave deviation signal Δ
rRDM (t) indicative of the deviations from the smooth platform motion;the method comprising; deviation cross-correlating the navigational deviation signal Δ
rNAV (t) and the wave deviation signal Δ
rRDM (t) to obtain a cross-correlation result K(t);determining a maximum of the resulting cross-correlation result K(t) as a function of time; setting the cross-correlation result K(t) equal to a time offset Δ
t; anddelaying the wave data by the time offset Δ
t prior to any image generation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
- rNAV (t) indicative of deviations from a smooth platform motion;
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16. An apparatus, mountable on a moving platform, for generating images from wave signals, comprising:
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a navigational system outputting a navigational deviation signal Δ
rNAV (t) indicative of deviations from a smooth motion of the platform;a wave unit receiving the wave signals and outputting a wave deviation signal Δ
rRDM (t) indicative of the deviations from the smooth motion of the platform;a deviation cross-correlator cross-correlating the navigational deviation signal Δ
rNAV (t) and the wave deviation signal Δ
rRDM (t) to obtain a cross-correlation result K(t); anda determining unit determining a maximum of the resulting cross-correlation result K(t) as a function of time and setting the cross-correlation result K(t) equal to a time offset Δ
t;
wherebythe wave data is delayable by the time offset Δ
t prior to any image generation to improve image quality. - View Dependent Claims (17, 18)
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19. An apparatus, mountable on a moving platform, for generating images from wave signals, comprising:
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means for outputting a navigational deviation signal Δ
rNAV (t) indicative of deviations from a smooth motion of the platform;means for receiving the wave signals and outputting a wave deviation signal Δ
rRDM (t) indicative of the deviations from the smooth motion of the platform;means for cross-correlating the navigational deviation signal Δ
rNAV (t) and the wave deviation signal Δ
rRDM (t) to obtain a cross-correlation result K(t); andmeans for determining a maximum of the resulting cross-correlation result K(t) as a function of time and setting the cross-correlation result K(t) equal to a time offset Δ
t;
wherebythe wave data is delayable by the time offset Δ
t prior to any image generation to improve image quality.
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Specification