Sampling requirements and alias-free processing in stripmap SAS systems

• Autorzy: Szczegielniak M. , Szczegielniak D.
• Języki publikacji: EN

Abstrakty

EN

Synthetic Aperture Sonar (SAS) is the high-resolution acoustic imaging technique which allows us to improve along-track resolution. In the era of digital processing, the proper sampling of signals and alias-free processing have an enormous influence on the efficiency of modern SAS systems. SAS processing without taking into account the aliasing phenomenon can cause a serious degradation of the reconstructed SAS image. Therefore, understanding the causes of this phenomenon in real SAS systems and ways of suppressing or avoiding its harmful effects seems to be indispensable. The aim of this paper is the comprehensive discussion of the along-track sampling problem, taking into account the slow-time Doppler support of the raw SAS signal, along-track mapping, effective target area and spatial filtering process as well as practical limitations of the along-track sampling connected with the SAS platform velocity or an maximum unambiguous range to imaged objects. The discussion was extended by mathematical dependencies derived or presented by authors. Moreover, numerical simulations in the Matlab environment was carried out by authors and the results are presented and discussed in this paper. The received raw signal was generated for a stripmap SAS system. Then, the spatial filtering by means of the Polar Formatting with the subdivision of the synthetic aperture was applied to filter out undesirable SAS signal contributions - the reason of the aliasing appearance in real SAS images. The final reconstructed SAS images were obtained by the ɷ-k algorithm. The carried out experiments confirmed the effectiveness of the presented approach for assumed SAS system parameters.

• Wydawca: Polskie Towarzystwo Akustyczne. Oddział Gdański
• Czasopismo: Hydroacoustics
• Rocznik: 2014
• Tom: Vol. 17
• Strony: 199--210
• Opis fizyczny: Bibliogr. 7 poz., rys.

Twórcy

autor

Szczegielniak M.

• University of Technology and Life Sciences,Kaliskiego 7, 85-792 Bydgoszcz, Poland

autor

Szczegielniak D.

• University of Technology and Life Sciences,Kaliskiego 7, 85-792 Bydgoszcz, Poland

Bibliografia

• [1] D.R. Wilkinson, Efficient Image Reconstruction Techniques for a Multiple-Receiver Synthetic Aperture Sonar, MSc thesis, 13-18, Electrical and Electronic Engineering at the University of Canterbury, New Zealand 2001.
• [2] M. Soumekh, Synthetic Aperture Radar Signal Processing, John Wiley & Sons, 238- 241, 402-411, USA 1999.
• [3] M. Szczegielniak, Spatial SAS Signal Filtering by Means of Polar Format Processing, Hydroacoustics, Vol. 9, 191-198, 2005.
• [4] M. Szczegielniak, Motion Compensation Problem in Stripmap SAS Systems, Hydroacoustics, Vol. 10, 45-54, 2007.
• [5] Hayden J. Callow, Signal Processing for Synthetic Aperture Sonar Image Enhancement, PhD thesis, 23, 24, 29, Electrical and Electronic Engineering at the University of Canterbury, New Zealand 2003.
• [6] Roy Edgar Hansen, Hayden John Callow, Challenges in Seafloor Imaging and Mapping With Synthetic Aperture Sonar, 3679, IEEE Transactions on Geoscience and Remote Sensing, Vol. 49, No. 10, October 2011.
• [7] Stefan Leier, Abdelhak M Zoubir, Aperture undersampling using compressive sensing for synthetic aperture stripmap imaging, content/2014/1/156, EURASIP Journal on Advances in Signal Processing (2014).