Badanie przetwornika o nierównomiernie rozmieszczonych elementach

General object of nonuniform array design is the approximation of desired beam pattern with reduced number of elements which are required for uniform array of d/α=0,5. This work intends to study possibilities of design procedures lead to useful, nonuniform arrays with elements situated in raster d/α=0,5. Options of spacing elements for nonuniform arrays presented beneath are reduced to the raster d/α=0,5, which enable easier technical realisation of the beamformer. Arrays with equal excited elements have been used, what is highly practical, both for transmission and receiving. Many designs of arrays have been proposed and tested The beam patterns for steered beams are presented

Stationary sonar for shallow water

The aim of the paper is checking possibility of building active stationary sonar designed for work in very shallow water, depth 8 - 10 m. Sonar is designed for monitoring very weak and moving targets by TS about -20 dB at the range up to few hundred metres. This paper presents construction of wide-sector sonar consists of two linear transducers. Beampatterns of the transducers are adjusted to conditions existing in very shallow water, particularly to minimize bottom and surface reverberation and effect of multipath propagation. Below are presented results of tests and measurements made for different types of targets and different environmental conditions - including: state of the sea, strong aeration of the near surface water, and influence of different sound propagation conditions for detection of the targets. The paper contains results of influence few types of signal processing for improvement SNR, thus increasing probability of the targets detection

Theoretical problems of the wideband sonar time-spatial filtration

The paper presents the synthesis of the time-spatial matched filtration algorithm. First part specifies base for the algorithm-input data. Successively, the matched filtration for continuous junction is depicted. This leads to the canonical form of the time-spatial filter. Consecutively, the decomposition into series connection of the matched and spatial filtration is realized. The next step is the signals approximation by Fourier series due to equivalence between approximation and interpolation on uniformly distributed discrete sampIes. The equation of the spatial filtration - in frequency domain - results from this mathematical operations. Application of the Bluestein's method to solve this equation provides to the final algorithm version. Advantages of the developed algorithm are presented in conclusions