## Efficient image reconstruction techniques for a multiple-receiver synthetic aperture sonar (2001)

Citations: | 1 - 0 self |

### BibTeX

@TECHREPORT{Wilkinson01efficientimage,

author = {David R. Wilkinson and B. E. (hons},

title = {Efficient image reconstruction techniques for a multiple-receiver synthetic aperture sonar},

institution = {},

year = {2001}

}

### OpenURL

### Abstract

Christchurch, New Zealand. Fast and efficient imaging techniques have been developed for reconstructing data from the single-receiver synthetic aperture sonar (SAS). Therefore, it is advantageous to be able to combine multiple-receiver SAS data into the single-receiver data equivalent to employ these existing algorithms. In this thesis, a method is developed for combining the data efficiently. This method can be used with SAS systems containing any number of hydrophones arbitrarily located in a linear array and with the imaging platform travelling at any velocity. Motion errors resulting from the towed platform deviating from its straight path need to be determined and compensated accordingly. Sway and yaw are the primary motion errors of concern in low glancing angle side-looking sonar, since they are the major cause of image errors and artifacts in the reconstructions. Algorithms for es-timating both sway and yaw are presented based on prominent points. These have shown to work well in simulations.

### Citations

470 | FFTW: an adaptive software architecture for the FFT
- Frigo, Johnson
- 2001
(Show Context)
Citation Context ...ents of two to three times may be expected over the corresponding Matlab functions. The FFTW package was developed by Matteo Frigo and Steven G. Johnson at the Massachusettes Institute of Technology [=-=Frigo and Johnson 1998-=-].s5.3 Using FFTW with Matlab 67 Before determining how we can use FFTW with Matlab, we need to briefly look at some of the operations of FFTW. For each transform of a given size the best routine or p... |

69 |
Matrix Eigensystem Routines— EISPACK Guide Extension
- Garbow, Boyle, et al.
- 1977
(Show Context)
Citation Context ... Matlab is a software program originally developed in Fortran to provide an easy interface to the very efficient numerical routines designed by the LINPACK and EISPACK projects [Dongarra et al. 1979, =-=Smith 1976-=-]. Since then, Matlab has considerably evolved to provide more extensive features that are specifically tailored to the engineer or research scientist. Matlab also has its own Application Program Inte... |

32 |
signal processing view of strip-mapping synthetic aperture radar
- Munson, Visentin
- 1989
(Show Context)
Citation Context ...focusing problems [Sheriff 1992]. Speckle may also be seen in reconstructed images as a mottled background. This is due to the coherent nature of synthetic aperture imaging [Bates and McDonnell 1986, =-=Munson and Visentin 1989-=-]. k x B kys12 SAS Image ReconstructionsChapter 3 MULTIPLE TO SINGLE RECEIVER SAS DATA COMBINING Several fast image reconstruction techniques, such as the wavenumber, chirp-scaling, and range-Doppler ... |

20 |
The theory and design of chirp radars
- Klauder, Price, et al.
- 1960
(Show Context)
Citation Context ...d pulse with a time delay shifted to baseband ω0 = carrier radian frequency k0 = carrier wavenumber ( ω0 c )s2.3 Pulse Compression 9 2.3 PULSE COMPRESSION Typically a method called pulse compression [=-=Klauder et al. 1960-=-] is used to improve the signal to noise ratio (SNR) of the signals. This reduces the peak power requirements of the transmitter without sacrificing range resolution. The most commonly used waveform f... |

20 |
Image reconstruction from frequency-offset Fourier data
- Munson, J, et al.
- 1984
(Show Context)
Citation Context ... spatial frequency domain. Thus, any window of the complete Fourier space is able to reconstruct the object reflectivity function to the resolution governed by the equivalent bandwidth of that space [=-=Munson and Sanz 1984-=-]. Therefore, accurate images from small portions of the object’s Fourier data may be generated.s8 SAS Image Reconstruction 2.2 RECEIVED ECHO COMPOSITION A simplification commonly used in synthetic ap... |

17 |
Synthetic Aperture Imaging Algorithms with application to wide bandwidth sonar
- Hawkins
- 1996
(Show Context)
Citation Context ...oes and the benefits of using pulse compression with our transmitted signal. The wavenumber algorithm is outlined, since this is the preferred method for reconstructing our synthetic aperture images [=-=Hawkins 1996-=-]. Finally, we describe the source of artifacts in the reconstructed images and how they differ between data from single and multiple-receivers. 2.1 REFLECTIVITY FUNCTION For each pulse, we transmit a... |

17 |
Fourier Array Imaging
- Soumekh
- 1994
(Show Context)
Citation Context ...nce between pulses. Thus, each pulse number can be translated into the corresponding aperture position u. Therefore, we can describe approximately the echoes detected at the receiver by equation 2.2 [=-=Soumekh 1994-=-]. � � eem(t, u) ≈ where: x y � � ff(x, y) · a(t, x, y − u) ⊙t pm t − 2 c �� � x2 + (y − u) 2 dx dy (2.2) eem(t, u) = received echoes for each transmitted pulse at position u ff(x, y) = object reflect... |

10 | Broadband Synthetic Aperture Sonar - Hayes, Gough - 1992 |

4 |
Imaging with a multiple-hydrophone synthetic aperture sonar
- Hayes, Gough
- 1999
(Show Context)
Citation Context ...ting image reconstruction algorithms are not lost. In this chapter an efficient and fast method is presented to combine data from any number of receivers with the platform travelling at any velocity [=-=Hayes and Gough 1999-=-]. 3.1 MULTIPLE-RECEIVER SAS MODEL The following sections describe the single-transmitter, multiple-receiver SAS model. Phase errors introduced by assumptions made in the SAS model are examined so the... |

4 |
Some early developments in synthetic aperture radar systems
- Sherwin, Ruina, et al.
- 1962
(Show Context)
Citation Context ...ON This chapter provides a brief overview of the field of Synthetic Aperture (SA) imaging [Wiley 1985]. From its humble beginnings in the field of Synthetic Aperture Radar (SAR) [Cutrona et al. 1961, =-=Sherwin et al. 1962-=-], applications using the underwater equivalent Synthetic Aperture Sonar (SAS) [Walsh 1969] are now being explored. The desire for increased mapping rates lead to the development of a multiple-receive... |

3 |
Synthetic Aperture Beamforming with Automatic Phase Compensation for High Frequency Sonars
- Sheriff
- 1992
(Show Context)
Citation Context ...defocusing, and speckle. Defocusing of objects in an image occurs when the actual and expected receiver’s along-track position differ. Variation in platform speed is one cause of defocusing problems [=-=Sheriff 1992-=-]. Speckle may also be seen in reconstructed images as a mottled background. This is due to the coherent nature of synthetic aperture imaging [Bates and McDonnell 1986, Munson and Visentin 1989]. k x ... |

3 |
Synthetic aperture radars
- Wiley
- 1985
(Show Context)
Citation Context ... MATLAB INTERFACE TO FFTW 87 E.1 FFTW M-Files 87 APPENDIX F CD CONTENTS 89 REFERENCES 91sChapter 1 INTRODUCTION This chapter provides a brief overview of the field of Synthetic Aperture (SA) imaging [=-=Wiley 1985-=-]. From its humble beginnings in the field of Synthetic Aperture Radar (SAR) [Cutrona et al. 1961, Sherwin et al. 1962], applications using the underwater equivalent Synthetic Aperture Sonar (SAS) [Wa... |

2 |
An efficient image reconstruction algorithm for a multiple hydrophone array synthetic aperture sonar
- Gough, Hayes, et al.
- 2000
(Show Context)
Citation Context ...tines typically compute two to three times faster than the equivalent Matlab routines. During the course of this thesis, two papers were written based on the algorithms developed in chapters 3 and 4 [=-=Gough et al. 2000-=-, Wilkinson et al. 2000]. 1.6 THESIS OUTLINE Chapter 2 presents the wavenumber algorithm, used as the algorithm of choice for reconstructing the SA data used throughout this thesis. The reconstructed ... |

2 |
Synthetic aperture sonar image reconstruction using a multiple-receiver towfish
- Pat
- 2000
(Show Context)
Citation Context ...pe of artifact is grating lobes. These occur in image space when the aperture is undersampled. Due to aliasing we get copies of the main lobe spaced evenly either side of the main lobe [Hawkins 1996, =-=Pat 2000-=-]. Two types of common image errors are defocusing, and speckle. Defocusing of objects in an image occurs when the actual and expected receiver’s along-track position differ. Variation in platform spe... |

2 |
Acoustic Mapping Apparatus
- Walsh
- 1969
(Show Context)
Citation Context ...85]. From its humble beginnings in the field of Synthetic Aperture Radar (SAR) [Cutrona et al. 1961, Sherwin et al. 1962], applications using the underwater equivalent Synthetic Aperture Sonar (SAS) [=-=Walsh 1969-=-] are now being explored. The desire for increased mapping rates lead to the development of a multiple-receiver SAS, introducing a new set of challenges to overcome. The chapter concludes with the con... |

1 | Stability of towfish used as sonar platforms - Preston - 1992 |

1 |
Azimuthal ambiguities in synthetic aperture sonar and synthetic aperture radar
- Rolt, Schmidt
- 1992
(Show Context)
Citation Context ...ed to slow forward velocities to prevent spatial undersampling along the aperture. Between transmitted pings, the platform can travel no further than half the linear extent of the largest transducer [=-=Rolt and Schmidt 1992-=-]. The other restricting factor is that the maximum unambiguous range is one-half the round trip distance travel in one pulse period. Thus, to improve the sampling rate either the pulse repetition rat... |

1 |
Sidescan sonar
- Somers, Stubbs
- 1984
(Show Context)
Citation Context ...ibutions made and an outline of this thesis. 1.1 REAL VERSUS SYNTHETIC APERTURE IMAGING Initially, sonar and radar imaging was typically performed using a side-looking real aperture (antenna) system [=-=Somers and Stubbs 1984-=-]. With the imaging system travelling along a straight path, a pulse is periodically transmitted perpendicular to the direction of travel. This pulse is then reflected back by targets of interest to t... |

1 |
Point spread variant acoustic imaging using synthetic aperture sonar
- Wilkinson, Gough, et al.
- 2000
(Show Context)
Citation Context ...pute two to three times faster than the equivalent Matlab routines. During the course of this thesis, two papers were written based on the algorithms developed in chapters 3 and 4 [Gough et al. 2000, =-=Wilkinson et al. 2000-=-]. 1.6 THESIS OUTLINE Chapter 2 presents the wavenumber algorithm, used as the algorithm of choice for reconstructing the SA data used throughout this thesis. The reconstructed images often have artif... |