Browsing by Subject "Beamforming"
Now showing items 1-19 of 19
-
A novel method to enlarge the scanning region of a focused beamformer
(NATO. SACLANTCEN, 1997)Often focused beamforming systems use the Fresnel approximation to compute the required delays. Unfortunately, such an approximation has a validity region that is very narrow around the broadside direction. To investrgate ... -
Alternative approach to passive sonar
(NATO. SACLANTCEN, 1987/10)An alternative approach to spatial processing for passive sonar is proposed and discussed. It is -
Application of beam-forming techniques to measurements of acoustic scattering from the ocean
(NATO. SACLANTCEN, 1986/10)Signals from an explosive source backscattered from the seafloor and received at long range by -
Detection of narrow-band low-level signals: simulated performance of high-resolution eigenstructure methods versus conventional beamforming
(NATO. SACLANTCEN, 1988/08)In this report the detection of narrow-band low-level signals by passive sonar is addressed, -
Evaluation of low-frequency bottom backscattering strength vs grazing angle by means of multiple beamforming
(NATO. SACLANTCEN, 1986/06)Bottom backscattering strength was measured in deep water as a function of grazing angle in the Balearic Abyssal Plain of the Mediterranean. The measurements were made with a towed, narrowband low-frequency omnidirectional ... -
High-resolution beamforming techniques performance analysis
(NATO. SACLANTCEN, 1986/11)Seven different beamforming techniques (including both conventional and high-resolution types) have been analyzed and compared in order to develop a quantitative relationship between resolution performance on the one hand ... -
Logarithmic least mean square sound-field estimation
(NATO. SACLANTCEN, 1987/03)The report deals with narrowband beamforming techniques for passive sonar applications. In particular, the Least Mean Square fit parameter estimation technique is used to estimate the spatial sound-field power density. To ... -
Measurement and interpretation of angular spreading from multiple boundary interactions in a shallow water channel
(NATO. SACLANTCEN, 1997)The problem of angular spreading of sound that has undergone multiple boundary scattering (both sea surface and sea bed) in a shallow water channel is discussed. Measurements made of the horizontal spatial coherence along ... -
Multiple beamforming
(NATO. SACLANTCEN, 1985/07)Beamforming techniques are generally based on the assumption that the received signal arrives from -
Noise measurements during MAPEX 2000
(NATO. SACLANTCEN, 2002/03)During MAPEX2000 some simultaneous ambient noise measurements with an HLA and satellite SAR images were collected. The aim was to predict shipping and wind noise from the satellite radar and to compare results with acoustic ... -
The ocean noise coherence matrix and its rank
(CMRE, 2019/05)An expression for the cross-spectral density matrix of ocean noise naturally separates into a Toeplitz part and a Hankel part [Harrison (2017). J. Acoust. Soc. Am. 141, 2812?2820]. The Toeplitz part is shown to be substantially ... -
Passive acoustic detection of marine mammals
(NATO. SACLANTCEN, 2000/04)A passive acoustic analysis of data recorded during the SACLANTCEN -
Performance assessment of the SACLANTCEN vertical array in shallow water
(NATO. SACLANTCEN, 1994/03)In this memoranduin the performance of the SACLANTCEN vertical -
Real-time expanded-band beamforming using a complex heterodyner and fast array processor
(NATO. SACLANTCEN, 1979/12)At the Defense Research Establishment Atlantic Dartmouth, Nova Scotia, Canada a data aquisition sytem been engineered to monitor and beamform data from element line arrays. This system has been designed to with either towed ... -
Results on the detection of narrow-band low-level signals in a ship-induced noise field using high-resolution beamforming
(NATO. SACLANTCEN, 1988/07)In this report the performance of a high-resolution beamformer is compared to that of the conventional -
Sonar beam-forming with an array processor in real time
(NATO. SACLANTCEN, 1979/12)A real-time sonar beam-forming system is described which consists of a minicomputer as host computer and an array processor. Beam-forming is accomplished by using the FFT algorithm in the processor. The system is also ... -
Sub-bands beam-space adaptive beamformer for port-starboard rejection in triplet sonar arrays
(CMRE, 2019/05)This paper addresses the problem of Port-Starboard (PS) beamforming for low-frequency active sonar (LFAS) with a triplet receiver array. The paper presents a new algorithm for sub-bands beam-space adaptive beamforming with ... -
Toeplitz constrained adaptive beamforming with auxiliary data
(NATO. SACLANTCEN, 1997/02)Submarine and mine detection using active sonar face similar problems when adaptive beamforming is required to provide high angular resolution or to suppress angularly isolated interferences. Both -
Virtual beams from an FFT beamformer and their use to assess the quality of a towed-array system
(NATO. SACLANTCEN, 1983/01)Linear towed arrays with sophisticated signal processing systems have become popular for passive sonar and seismic prospecting. This is due to the ease of mobility and the large spatial gains achievable. However, because ...