A novel beamformer for circular sonar arrays
A new Beamformer (BF) technique using Linear Deltamodulation (DM) on the spatially sampled circular array sensor signals is presented. In this method, the FIR-type of beam-former implementation for circular arrays results in an extremely simplified hardware which does away with multipliers and retains basically adders. Thus, the immediate problem of large word-size is considerably resolved. The DM-type of BF by virtue of the implementation, provides an additional advantage of beam-space interpolation. Various aspects of array gain, sidelobes and noise performance are dealt with the help of simulation studies. Hardware structures both for fixed and programmable beamformer coefficients are also proposed which bring out the potential of this technique for compact sonar systems.
A novel compact beamformer for a high resolution sonar
A novel technique for implementing the CZT-beamformer for high-resolution sector scanning sonar which results in a very compact hardware is presented. A Delta-modulator is used to encode the spatially sampled sensor signals from a linear array in single-bit format, thus allowing the use of shift registers in place of analog bbd's. Another novel feature is the combination of bandpass sampling and spatial multiplexing into a single operation. The paper discusses this implementation of the CZT-beamformer, and provides simulation results and comparison with the conventional CZT-beamformer. These results demonstrate the potential of the novel technique for compact systems. A complete beamformer hardware has also been developed for a specific application.
Quantizing Characteristics for Signals Having Laplacian Amplitude Probability Density Function
The optimum (minimum mean-squared-error criterion) and optimum uniform quantizer characteristics for signals characterized by the Laplacian amplitude probability density function are given in tabular form. These results correct and extend previously published results.