Parallel hardware implementation of radar electronics equipment for a laser inspection system

An amplitude modulated laser radar has been developed by ENEA (Italian Agency for new technologies, energy and environment) for periodic in-vessel inspection in large fusion machines (ITER). The system is able to obtain a complete 3D mapping of the in-vessel surface. First, a digital signal processing system was developed to modulate the laser beam and to detect both the amplitude of the back scattered light and the phase difference between it and the modulation signal. This system is based on commercial digital receiver and parallel DSP (digital signal processing) boards on a VME bus. It reaches a speed of 100 K measures/s showing good accuracy and stability. Starting from this, further development has been done to increase the speed up to 2.328 M measures/s. To reach the sub-microsecond speed it was necessary to implement the mathematical algorithm in a highly parallel hardware architecture using FPGAs (field programmable gate array). Looking at the good results of previously developed system it was decided to maintain the same acquisition front-end. The last release of A/D converters was used to increase the operating frequency up to 200 MHz, but the previously used software algorithm was completely redesigned and optimized to be used in the FPGA hardware architecture.