FMCW SAR THESIS

It corrects for the non-linearity effects for the whole range profile at once, and it allows a perfect range focussing, independently of the looking angle. In addition, the voltage controlled oscillator VCO adds a certain degree of phase noise and nonlinearity to the transmitted signal that degrades the signal-to-noise ratio SNR , range accuracy and image resolution. A flight test campaign has been organized during the last part of Again, proper processing methods to overcome such limitation due to frequency non-linearities were not available to the scientific community. They consume little power and, due to the fact that they are continuously operating, they can transmit a modest power, which makes them very interesting for military operations. Also the concept of synthetic aperture with FMCW sensors has already been put forward in literature, and some experimental systems have been described. This work seeks to overcome the three design issues mentioned above through the development of simulation platforms, which has been shown to be well-suited for the comprehensive study of these effects.

Within the framework of the project, the following novelties and main results have been reached and are presented in the thesis: As in conventional pulse SAR systems, the stop-and-go approximation could be used; such an approximation assumes the radar platform stationary during the transmission of the electromagnetic pulses and the reception of the corresponding echoes. The novel combination of FMCW technology and SAR techniques leads to the development of a small, lightweight and cost-effective high resolution imaging sensor. Also the concept of synthetic aperture with FMCW sensors has already been put forward in literature, and some experimental systems have been described. A flight test campaign has been organized during the last part of

Consequently, FMCW radar technology is of interest for civil and military airborne earth observation applications, specially in combination with high resolution Synthetic Aperture Radar SAR techniques.

For airborne FMCW aar, however, the stop-and-go approximation can be not valid anymore because the platform is actually moving while continuously transmitting.

Again, proper processing methods to overcome such limitation due to frequency non-linearities were not available to the scientific community.

fmcw sar thesis

Skip to main content. Electrical Engineering, Mathematics and Computer Science. Finally, several avenues of further study and applications are suggested. Thanks to the special algorithms developed, FMCW SAR images with a measured 45 cm times 25 cm resolution including windowing were obtained for the first time.

  CHAPTER 14 TRICARE AND CHAMPVA CRITICAL THINKING

SAR techniques have been successfully applied in combination with coherent pulse radars. In practical FMCW sensors, specially when using cheap components, the presence of unwanted non-linearities in the frequency modulation severely degrades the radar performances for long distances.

One of the limiting factors of FMCW radars is that the ramp signal modulates fmxw received signal, which limits the f,cw achievable range resolution.

Moreover, to be of interest for the civil market, cost effectiveness is mandatory.

To demonstrate the effectiveness and versatility of the proposed signal processing procedure, an S-band FMCW radar system, using off-the-shelf components, is designed for near distance target imaging using linear and circular SAR techniques.

Subject sar radar fmcw To reference this document use: The proposed method operates directly on the deramped data tyesis it is very computationally efficient.

FMCW-SAR System For Near Distance Imaging | ERA

dmcw It corrects for the non-linearity effects for the whole range profile at once, thesiis it allows a perfect range focussing, independently of the looking angle.

The results were very successful. They consume little power and, due to the fact that they are continuously operating, they can transmit a modest power, which makes them very interesting for military operations. However, the practical feasibility of an airborne FMCW SAR was not evident; the experimental sensors described in literature were, in fact, radars mounted on rail supports operating in ground SAR configurations and at short distances.

fmcw sar thesis

A flight test campaign has been organized during the last part of Additionally, the effect of bandwidth, integration angle and phase noise of the received pulses on the SAR image resolution in both range and cross-range directions are comprehensively studied.

In addition, the voltage controlled oscillator VCO adds a certain degree of phase noise and nonlinearity to the transmitted signal that degrades the signal-to-noise ratio SNRrange accuracy and thesi resolution. The novel combination of FMCW technology and SAR techniques leads to thesix development of a small, lightweight and cost-effective high resolution imaging sensor.

The FMCW radars could perform measurements in each position of the synthetic aperture and then be moved to the next one.

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fmcw sar thesis

Fmc signal processing procedure with system calibration methods to mitigate the effects of deramp, phase noise and nonlinearity of the VCO on the beat spectrum is proposed. Also the concept of synthetic aperture with FMCW sensors has already been put forward in literature, and some experimental systems have been described.

FMCW-SAR System For Near Distance Imaging Applications

Within the framework of the project, the following novelties and main results have been reached and are presented in the thesis: Such sensors are foreseen to play an important role in small-scale remote sensing applications, such as the monitoring of dikes, watercourses, or highways. Furthermore, such sensors are of military interest; reconnaissance tasks could be performed with small unmanned aerial vehicles UAVsreducing in this way the risk for one’s own troops.

To resolve these issues, a multitude of hardware and software approaches have been proposed for the suppression of phase noise and nonlinearity of the transmitted signal.

To improve the range accuracy, different calibration methods are also comprehensively studied. As in conventional pulse SAR systems, the stop-and-go approximation could be used; such an approximation assumes the radar platform stationary during the transmission of the electromagnetic pulses and the reception of the corresponding echoes.

This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law. The reconstructed images show the improvement of image quality and accuracy in the target position.

The author has developed a very novel processing solution, which completely solves the problem of the presence of frequency non-linearities in FMCW SAR.

In order to be operated from small, even unmanned, aircrafts, such systems must consume little power and be small enough to fulfill the usually strict payload requirements.