10-04-2017, 09:09 PM
Image formation for Synthetic Aperture Radar using MATLAB
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EXECUTIVE SUMMARY
The main aim of this project will be to analyse the code in MATLAB to extract images from the data downloaded of a SAR (Synthetic Aperture Radar) satellite (ERS-2). These satellites by sending a chirp to the earth and acquiring the reflection of the ground surface, obtain some data. This data must be treated correctly though to acquire the images of the surface we want to define. To obtain the final image there are some basic steps to follow to do it properly. Moreover there will be some steps which will be done on board in the satellite; these would be the demodulation and the digitization of the data.
TERMS OF REFERENCES
Defining the scope in which the project will be done, we start from the premise that it will be a research project, based on the information available in the library and internet source. The program which is going to be used to treat the images is the MATLAB, this program works perfectly due it is a numerical computing environment and programming language which allows you to manipulate matrix, plotting of functions and data, implementation of algorithms and create your own code. That program is quite complex and wide so it will be useful to know what kind of functions and statements will be useful for this kind of project, and study them in depth. It will also be necessary to find and understand any other code created to plot the satellite data.
Brief History
Radar beginnings are based on the electromagnetic waves behaviour, proposed by James Clerk Maxwell in 1864. Heinrich Hertz was the first one to demonstrate these laws in 1886 with his physical experiments. And the first one who suggested take advantage of the echo in the naval navigation was Christian H lsmeyer. On the other side Guglielmo Marconi develop an instrument with the same characteristics [1].
Basic Concepts
The operation of the RADAR s (RAdio Detection And Ranging) consists of a pulse radiated into the free space through an antenna. The electromagnetic energy propagates outward at light velocity, scattering from all the objects finds on its way. The objects can be detected because the energy they scatter imitates the frequency and the duration of the transmitted pulse and provides the information on:
1. - magnitude
2. - phase
3. - time interval between pulse emission and return from the object
4. - polarization
5. - Doppler frequency
Doppler Effect
In 1842 Christian Doppler, an Austrian mathematic and physicist wrote his monograph On the coloured light of the double stars and certain other stars of the heavens . In this monograph he talked about the shift in frequency and wavelength of waves which results from a source moving with respect to the medium, a receiver moving with respect to the medium, or even a moving medium.