Ankara : The Department of Electrical and Electronics Engineering and The Graduate School of Engineering and Science of Bilkent University, 2014.Thesis (Master's) -- Bilkent University, 2014.Includes bibliographical references leaves 66-68.Performance of coded signals in active Sound Navigation and Ranging
(SONAR) technology is studied in this work. In this work, the possibility of
having covertness and environment friendliness in SONAR systems is
investigated. Spread spectrum ping signal is considered to achieve low
probability of detection and interception, while maintaining good performance.
Direct Sequence Spread Spectrum (DSSS) coded transmitted signals having a
sequence type of maximal with lengths from 7 chips to 127 chips and tone burst
pulse having single length as a reference signal are used as spread spectrum ping
signal. The length of the tone burst pulse can not be increased indefinitely
because of the multipath propagation. The problem of detection and localization
of the targets and the cross correlation properties of the maximal length
sequences are investigated as well. The Signal to Noise Ratio (SNR) and Signal
to Interference and Distortion ratio (SINAD) are important parameters in
detection and localization of the targets. It is found that as the number of chip
length increases, the SNR and SINAD increase but the improvement of the
SINAD is comparatively less because of the cross correlation properties of the
maximal length sequences.Kumru, YasinM.S
