FMCW SAR THESIS

FMCW SAR THESIS

The proposed method operates directly on the deramped data and it is very computationally efficient. The author has developed a very novel processing solution, which completely solves the problem of the presence of frequency non-linearities in FMCW SAR. 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. Skip to main content. The FMCW radars could perform measurements in each position of the synthetic aperture and then be moved to the next one. The reconstructed images show the improvement of image quality and accuracy in the target position.

The FMCW radars could perform measurements in each position of the synthetic aperture and then be moved to the next one. Subject sar radar fmcw To reference this document use: 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. 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. Electrical Engineering, Mathematics and Computer Science. 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.

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.

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. Within the framework of the project, the following novelties and main results have been reached and are presented in the thesis: 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.

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. 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.

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fmcw sar thesis

The FMCW radars could perform measurements in each position of the synthetic aperture and then be moved to the next one. In the field of airborne earth observation there is special attention to compact, cost effective, high resolution imaging sensors.

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FMCW-SAR System For Near Distance Imaging Applications

Also the concept of synthetic aperture with FMCW sensors has already been put forward in literature, and some experimental systems have been described. A combination of frequency-modulated continuous-wave FMCW technology with synthetic aperture radar SAR principles is a highly sought after method as it leads to a compact thesia cost effective high resolution near distance imaging system.

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. 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.

Such sensors are foreseen to play an important role in small-scale remote sensing applications, such as the monitoring of dikes, watercourses, or highways.

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. The proposed method operates directly on the deramped data and it is very computationally efficient.

Signal processing of FMCW Synthetic Aperture Radar data

The novel combination of Thesiis technology and SAR techniques leads to the development of a small, lightweight and cost-effective high resolution imaging sensor. A flight test campaign has been organized fmcs the last part of As in conventional fmccw 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.

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

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Electrical Engineering, Mathematics and Computer Science. One of the limiting factors of FMCW radars is that the ramp signal modulates the received signal, which limits the minimum achievable range resolution.

A low-power radar imaging system

Finally, several avenues of further study and applications are suggested. To improve the range accuracy, different calibration methods are also comprehensively studied.

fmcw sar thesis

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

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. Subject sar radar fmcw To reference this document use: The reconstructed images show the improvement of image quality and accuracy in the target position. The author has developed a very novel processing thfsis, which completely solves the fncw of the presence of frequency non-linearities in FMCW SAR.

fmcw sar thesis

A signal processing procedure with sat calibration methods to mitigate the effects of deramp, phase noise and nonlinearity of the VCO on the beat spectrum is proposed. Again, proper processing methods to overcome such limitation due to frequency non-linearities were not available to the scientific community.

The results were very successful. 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.