Fast Realization Of High Resolution Multi-subarray Detection Method Based On FPGA

High resolution multi-subarray amplitude-phase united detection method is a new technique for seafloor topograph detection. It has high estimation accuracy, high resolution and good reliability in practical applications. This method is different from traditional methods. It divides a multi-sensors linear array into multiple overlapped subarrays, and applies beamforming technology to each subarray, then estimates the amplitude and phase using interested directional data, but the method involves huge computation, it's difficult to accomplish real-time operation with a single DSP, even if using one with high speed. Therefore, in this paper, the research focuses on the real time implementation of this high resolution seabed terrain detection method. It puts forward a fast realization means. In the design, we combine FPGA with DSP to process, but FPGA is employed as core processor, let FPGA accomplish the algorithms based on data streaming whose structure is fixed, and also the matrix operations whose computational complexity is very large. In doing so, it will bring many advantages, such as making full use of the characteristics and advantages of FPGA, saving resources, ae well as greatly improving work efficiency and detection performance. And it solves the problem that the method is difficult to realize in real time in pratical project.The design of FPGA's inner logic part is the core content of this paper. The system chooses EP2C50F484, one of the Cycloneâ…¡series chips from Altera company, as hardware flat. And the accomplished function modules include a 19-order hilbert convertor, data smoothing, window function weighting, data buffer, zero-padding, data result upload and FFT beamforming. Moreover, in order to improve the real-time performance of the system, the design on overlapped subarray formation, natural phase compensation and the solution of phase difference series which are based on multi-subarray amplitude-phase united detection method is also completed.The all design content has been applied to high resolution shallow multibeam bathymetric system. Its hardware plat has been validated for many times by computer emulation; furthermore, we have also undergone underwater tests and navigation tests to verify system function, specification and stability in the water tank of Harbin Engineering University, the anechoic tank of HaiYing factory in WuXi, the MoGanshan reservoir in Zhejiang province and the Songhua lake in Jilin province. And the result is satisfied, it proves that the method mentioned in the paper not only is of high calculation speed, but also has great stability and reliability.