Communications: directive radio wave systems and devices (e.g. – Synthetic aperture radar
Patent
1993-09-23
1994-06-21
Barron, Jr., Gilberto
Communications: directive radio wave systems and devices (e.g.,
Synthetic aperture radar
342161, G01S 1390
Patent
active
053231627
ABSTRACT:
A synthetic aperture radar system is mounted in a moving platform. The synthetic aperture radar system includes a multi-beam antenna having a plurality of reception beams different in direction from one another, the multi-beam antenna being adapted to receive radar echoes from objects. The width of each of the reception beams is selected such that the band width of a Doppler shift contained in the radar echo of a moving object is broader than that of a Doppler shift contained in the radar echo of a stationary object. The radar echo is pulse compressed to improve the range resolution before the frequency thereof is shifted such that the center frequency of the Doppler shift due to the velocity of the moving platform becomes zero. After the frequency shifting, the radar echo is filtered to separate the radar echoes of the moving and stationary objects from each other. The radar echoes of the moving and stationary objects are respectively subjected to Fourier transform with respect to the distance between the moving platform and the objects. The spectrum of the radar echo from the moving object is further shifted such that the center frequency of the Doppler shift due to the velocity of the object becomes zero. These reception, pulse compression, frequency shift and Fourier transform are executed for each reception beam. The spectrums in the radar echoes of the moving and stationary objects are respectively synthesized for all the reception beams. After the synthesization, the spectrums are respectively multiplied by a reference spectrum in the complex manner. The results of the multiplication are respectively inverse transformed from the spectrums.
REFERENCES:
patent: 4965582 (1990-10-01), Hellsten
patent: 4989008 (1991-01-01), Fujisaka et al.
patent: 5059966 (1991-10-01), Fujisaka et al.
patent: 5122803 (1992-06-01), Stann et al.
Donald R. Wehner "High Resolution Radar", 1987.
J. C. Kirk, Jr. "Motion Compensation for Synthetic Aperture Radar IEEE Transactions on Aerospace & Electronic Systems", May 1975.
Fujisaka Takahiko
Kondo Michimasa
Oh-Hashi Yoshimasa
Barron Jr. Gilberto
Mitsubishi Denki & Kabushiki Kaisha
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