Sidelobe Cancellation Algorithm Study And Implementation Based On L-Band Phased Array Radar

With the wide used of the phased array radar in various fields, side-lobecancellation algorithm in phased array radar is becoming more and more important. Inrecent decades, scholars at home and abroad have paid more attention on side-lobecancellation algorithm, and have successfully applied it to array signal processingsystems. As well known, the general side-lobe cancellation algorithm is used to beemployed in narrow-band system. However if the narrow-band side-lobe cancellationalgorithm is directly utilized in the wide-band system, the performance of thecancellation capability will degrade.Firstly, this thesis analyzes a non-adaptive narrow-band side-lobe cancellationalgorithm. Based on the phased array, the algorithm firstly calculates the weight valuewhich can cancel array side-lobe, and then stores the right weight. In the process of thesystem, it firstly estimates the interference direction to determine the side-lobe whichneeds to be canceled, and then reload the stored value into cancel side-lobe. Thenon-adaptive side-lobe cancellation algorithm only cancel side-lobe of one interferencesignal，and estimation error of interference direction will greatly undermine the sidelobe cancellation capability of the system.Secondly, the thesis also studies the adaptive side-lobe cancellation algorithm. Thealgorithm overcomes the defects caused by the non-adaptive side-lobe cancellationalgorithm. Needing no estimating interference direction, it can cancel side-lobe of moreinterference signals by adding multiple secondary array elements, which improve thecancellation performance of the system.If a common adaptive side-lobe cancellation algorithm is directly used in thewidened bandwidth system, it will cause serious damage to the cancellation ability. Inother words, common adaptive side-lobe cancellation algorithm can not be directlyapplied to the wideband system. To solve this problem, the thesis also analyzes theinfluence of bandwidth on the common adaptive side-lobe cancellation algorithm, andstudies wide-band adaptive side-lobe cancellation algorithm based on sub-band. Thesimulation result shows that the algorithm can effectively cancel side-lobe of wide-band signal. Wide-band adaptive side-lobe cancellation algorithm based on sub-band resolvesthe received wide-band signal into a number of sub-band signals with the analysis filterbank, and then cancels side-lobe for each sub-band signals, respectively. At last the errorsignal output of each sub-band side-lobe is synthesis into the system output by synthesisfilter bank.Finally, the thesis desgians and analysizes the implementation of sub-bandside-lobe cancellation algorithm on FPGA, which includes the implemenation ofsub-band dividing of board-band signal and adaptive side-lobe cancellation algorithm ineach sub-band. What’s more, the function of every cell of FPGA design is vertified viathe behavior simulation.