Recursive system for image forming by means of a spotlight synthetic aperture radar

• US 5,061,931 A
• Filed: 07/23/1990
• Issued: 10/29/1991
• Est. Priority Date: 07/23/1990
• Status: Expired due to Fees

• Current Assignee: Selenia-Industrie Elettroniche Associate SPA (Leonardo S.p.A.)
• Original Assignee: Selenia-Industrie Elettroniche Associate SPA (Leonardo S.p.A.)
• Inventors: Morabito, Carlo F., Farina, Alfonso
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US07/557,309
• Time in Patent Office: 463 Days
• Field of Search: 342/25
• US Class Current: 342/25.00F
• CPC Class Codes: G01S 13/9004 SAR image acquisition techniques
• CPC Class Codes: G01S 13/904 SAR modes
• CPC Class Codes: G01S 13/9052 Spotlight mode

Abstract

Recursive system for the forming of a radar image by means of a SAR sensor, for application preferably related to the radar field, essentially having a monodimensional transformation system (1) of the signal received by the radar; a convolution element (2) of the same signal by means of a monodimensional inverse transformation (3). The result of the convolution is retro-projected by means of element (4). In turn, the result of this operation, envelope-detected (5), provides an estimate of the electromagnetic characteristics of the teledetected scene. The invention belongs to the radar application field, and more precisely to that of synthetic aperture radars for teledetection. It finds its best application in the area of synthetic aperture radar signal processing.

Claims

1. A recursive signal processing device for forming an image of a teledetected scene from a radar signal through use of synthetic aperture radar signal in spotlight mode, comprising:

means for receiving said radar signal;

monodimensional transformation element means for acting upon said radar signal in accordance with a monodimensional FFT algorithm for producing a first processed signal;

inverse monodimensional transformation element means for acting upon said radar signal in accordance with an inverse monodimensional FFT algorithm for producing a second processed signal;

convolution means for convoluting said first and said second processed signals together to produce a third processed signal;

retroprojection means for performing a retroprojection integration of said third processed signal to produce a fourth processed signal; and

envelope detection means for extracting a module of an estimated reflectivity function from said fourth processed signal for providing an estimate of the electromagnetic characteristics of said teledetected scene.

2. A recursive signal processing device for forming an image of a teledetected scene from a radar signal through use of synthetic aperture radar in spotlight mode, comprising:

means for receiving an analog radar signal;

an a/d converter for converting the form of said received analog radar signal into a first digital signal;

a first shift register for receiving said first digital signal from said a/d converter and storing said digital signal as a first stored digital signal;

first transforming means for transforming said first digital signal into a first processed signal by acting upon said first digital signal in accordance with a monodimensional FFT algorithm;

a second shift register for receiving said first processed signal from said transforming means and storing said first processed signal as a first processed stored signal;

look-up table means for generating a second digital signal;

transforming means for transforming said second digital signal into a second processed signal by acting upon said second digital signal in accordance with an inverse monodimensional FFT algorithm;

convolution means for taking said first and said second processed signals and convoluting them together to produce a third processed signal;

a third shift register for receiving said third processed signal from said convolution means and storing said third processed signal as a third processed stored signal;

switching means for manipulating each of said first, second and third processed stored signals in accordance with switching logic means and coordinate transformer means, and producing an output;

a multiplicity of memory elements for receiving and storing said output as data;

envelope extraction means for extracting data from said memory elements which is a function of the teledetected image; and

recording means for receiving and recording said extracted data.