K omega beamforming implementation on IBM cell processor

Abstract

The frequency domain beam forming techniques specially using 2D-FFT process are used mostly in passive sonar. It provides good results mostly in applications like towed arrays that are towed behind submarines and ships. The linear hydrophone array is sampled in time .The data is transformed from time domain into frequency domain by FFT process. Then another FFT is applied along the nth frequency bin in space. This provides good frequency contents of the towed arrays. The plot obtained from this 2D-FFT process is called k-omega plot. In which frequency is on x axis and wave number k on y axis. K-omega beam forming is widely used in passive sonar for detection, classification and localization purposes. The technique requires uniform linear array for beam forming. The linear hydrophone arrays are split into further sub arrays. These sub arrays are spaced spatially according to different cut frequencies. With the introduction of long passive arrays for naval and oil exploration purposes, the parallel K-omega processing problems becomes complex. Traditionally the implementation is done on cluster of IBM PowerPCs or more recently Intel Xeon clusters. The heavy computation load is often compromised with more optimized algorithms fit to specific architecture. This in practice requires major overhaul in the system if new feature is to be incorporated in the passive towed array sonar system. In this research paper the K-omega beam forming is implemented on IBM cell processor. The cell processor with its inherent parallelism in architecture provides an opportunity to execute processing of sub arrays concurrently. The K-omega beam forming is implemented on simulated 5 to 7 nested sub arrays and results are computed in simulator and tested against the Matlab outputs. The k omega beam forming used in this implementation depends on FFTW library along with IBM math, vector and matrix libraries. The implementation is benchmarked using IBM cell processor simulator. Another aspect of cell processor found in this research paper is its very fine memory handling capability. This is vital for Matrix calculations and iterative tasks. From the implementation it is evident that this can be easily ported to commercially available system i.e. Sony playstation 3. The Sony playstation 3 with Linux fedora core 6 is ideal for such an application and it can be used for training of passive sonar operator.