Browsing Technical Reports by Subject "Signal processing"
Now showing items 1-20 of 40
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A simple deconvolution method for NAPOLI'85
(NATO. SACLANTCEN, 1991/10)An inverse filter (deconvolution in the frequency domain) is applied -
Active signal detection in shallow water using the Page test
(NATO. SACLANTCEN, 1996/11)The use of active sonar in shallow water results in received echoes that may be considerably spread in time compared to the transmitted wave form. The duration and structure of the spreading and the time of occurrence of ... -
Alternative approach to passive sonar
(NATO. SACLANTCEN, 1987/10)An alternative approach to spatial processing for passive sonar is proposed and discussed. It is -
An analogue recording system for recording pulse series
(NATO. SACLANTCEN, 1964/04)An analogue recording system for the visual display of pulse series intermittently received from oceanographic sensors is described. It is composed of a mechanically-modified pen recorder and a newly designed electronic ... -
An analytical study of source localization in shallow water by matched-field processing of horizontal arrays
(NATO. SACLANTCEN, 1992/08)Over the last few years a large number of studies have reported results of range-depth localization of sound sources by matched-field processing of vertical arrays in known environments. The performance of matched-field ... -
An experimental study in forming a long synthetic aperture in the sea
(NATO. SACLANTCEN, 1992/09)Successful experimental testing of synthetic aperture techniques for sonar systems have been very limited and only few results, including very stable CW signals, have been published. These experimental results and theoretical ... -
Application of real data to sonar detection by neural networks
(NATO. SACLANTCEN, 1992/11)This memorandum describes the results of applying an artificial neural network for the detection of target echoes. The present study is a continuation of work conducted in 1989 in which a three-layer artificial neural ... -
Channel sensitive processor: real data processing
(NATO. SACLANTCEN, 1998/02)The CSP is applied to data collected during the DUSS97 sea trial. A one-way geometry is used and the transmitted signal propagation time is known a priori. As predicted by analytical and simulation studies, the CSP detector ... -
Channel-sensitive processor: development and detection performance evaluation
(NATO. SACLANTCEN, 1997/03)A Channel Sensitive Processor (CSP) which improves upon the detection performance of the traditional matched filter is developed. This method compensates for the performance degradation of the matched filter due to dense ... -
Delay-Doppler resolution performance of large time-bandwidth product linear FM signals in a multi- path ocean environment
(NATO. SACLANTCEN, 1989/04)Active sonar systems that transmit large time-bandwidth (TW)-product linear frequency modulated (LFM) waveforms and receive echoes from targets of unknow~r~an ge and speed can suffer considerable correlation losses that ... -
Detection of objects on a non Rayleigh background
(NATO. SACLANTCEN, 1995/12)Sector scanning sonar systems image the sea-bottom to detect objects that can be distinguished from the background structure of the seabottom. In current systems images are displayed and discarded as new image data become ... -
Digital analysis working group: proceedings of a conference held at SACLANTCEN on 25-27 May 1971
(NATO. SACLANTCEN, 1972/05) -
EM phenomena in the ELF range: natural background noise and instrumentation for its measurement
(NATO. SACLANTCEN, 1965/06)The report is the second of a series of three that discusses various EM phenomena in the ELF range. A general outline of the natural background noise in the frequency range between 1 and 50 cps is given and the measurement ... -
Estimators for model-based passive localization
(NATO. SACLANTCEN, 1988/07)A comparative study is made of the performance of four different estimators as used in the matched field technique of passive localization. The study is based on both real and synthesized data. In the synthesized data case, ... -
Extended towed-array processor by overlapped correlator
(NATO. SACLANTCEN, 1988/11)The development of an algorithm for extended towed-array measurements, which could be used by matched-field estimators to obtain information about depth and range of a source, is studied. This algorithm combines coherently ... -
Formulae for bistatic signal and reverberation
(NATO. SACLANTCEN, 2002/12)This report demonstrates that it is possible to obtain closed-form solutions for signal and reverberation in a wide variety of bistatic scenarios including ducts and bottom bathymetry. These formulae adapt earlier monostatic ... -
Frequency deviation indicator
(NATO. SACLANTCEN, 1963/11)A new type of discriminator was developed to measure the frequency variation of electrical signals; it has the special feature to indicate without any delay the difference between the signal frequency and some fixed reference ... -
High-resolution analysis of non-stationary data ensembles
(NATO. SACLANTCEN, 1980/10)Estimation of an unknown parameter of a random data ensemble is usually done by maximizing a certain power estimator by varying the unknown parameter. This method is convenient where the data are a nonlinear function of ... -
Impact of uncertain environmental knowledge on the shallow-water transfer function
(NATO. SACLANTCEN, 1992/12)It is assumed that the acoustic channel can be modeled as a linear time-invariant space-variant filter. In this case, from linear systems theory, it is known that the filter output, that is the predicted source signal ... -
Limitations on towed array gain imposed by a non-isotropic ocean
(NATO. SACLANTCEN, 1990/08)This study deals with the limitations imposed by ocean characteristics on hydrophone array gain and on attempts to create a synthetic aperture using towed-array measurements. The multi-element synthetic or physical aperture ...
