Patent RU-2392635-C2 (RU)
Inventor: BRYZGALOV ALEKSANDR PETROVICH
IPC: G01S5/02
Filed: 2008-06-04
Granted: 2010-06-20
Abstract: FIELD: physics, navigation. 
     SUBSTANCE: invention relates to methods for radar detection on the locality of small objects. The location method, which is based on using side-looking synthetic aperture radar (SAR) mounted on a carrier in form of aircraft, involves generation of preliminary data on the search object and its coordinates, determination of the flight path of the carrier and the location zones for the SAR based on these data, flying the aircraft to the given path and location of these zones using SAR with simultaneous determination using the navigation system (NS) of the aircraft and recording the spatial position of phase antenna centres (PAC) of the SAR during each probing, obtaining long-wave holograms at the output of the SAR and recording the said holograms, formation of a radar image of given location zones based on the long-wave holograms and spatial positions of the PAC, detection of an object on that radar image, its identification and determination of its geodesic coordinates; K≥2 SAR channels operating in different frequency ranges are used. Resolution in the channel with the greatest carrier frequency and with the best resolution is matched with dimensions of the detected object. During location, primary detection of the object in the location zone is carried out first, selecting a SAR channel with the best contrast of the signal of the search object on the background of the locality, and results of primary detection are used in the channel with the greatest carrier frequency, for which fragments of the detailed radar image are formed, the number, position and dimensions of which correspond to primary detection data. The search object is detected and identified on these fragment and its position in the screen coordinate system is determined, the position in a geodesic coordinate system of which is determined from estimations of geodesic coordinates of the SAR PAC of that channel, and further, geodesic coordinates of the object are recalculated. To increase efficiency of the method, additional location of selected sections of the locality using a high resolution channel is carried out based on results for primary detection of the object. For the same purpose, a search zone is further formed on radar images formed in primary detection channels and primary detection of the object is carried out in that zone. If there is a passive locator (PL) on the carrier during detection and determination of the coordinates of the object, whose position is related to a radiofrequency radiation source, generation of preliminary data on the search object and selection of SAR parametres is carried out from data of this PL, where if possible, the path of the carrier is used to make a synthesised passive antenna system, optimising it and operating time of the PL and SAR. To achieve the required accuracy of determining coordinates of the object, requirements are specified for NS data when evaluating PAC during single probing of the location zone and during repeated probing while changing the aspect by an angle close to 90 degrees. Proposed also are methods for smoothing NS data based on features and requirements for side-looking SAR in the solved tasks, as well as use of self-focusing in a long-wave channel in order to correct NS errors. 
     EFFECT: method increases efficiency of on-line detection of a small object and accuracy of determining its geodesic coordinates. 
     11 cl, 6 dwg