| Because of conventional narrowband adaptive beamforming technique can realize agilebeam direction control which can obtain high gain of signal processing and stronginterference rejection, it is now widely used in radar, communication, navigation, speechsignal processing, seismic testing, and etc. But when signals with a certain bandwidth neededto be processed, espaically broadband signal, the beam pattern of an array will be changedwith the factor of frequency, which can be heavily affecte performance of the array. Thecomputation of broadband beamforming is very large and there will be not enough resourcesto deal with it for most of the hardware system. So, how to use a limited amount ofcomputation to realize broadband signal receiving as well as broadband interferencesuppression of a certain communication system is worthwhile to study. This paper hasfinished the design and manufacture of the hardware platform for broadband beamformingfeaturing a low complexity and also finished the realization of a wideband adaptivebeamforming algorithm in the hardware platform.First of all, this paper introduces several narrow band adaptive beamforming algorithmbased on linear array model as well as two kinds of broadband adaptive beamformingalgorithm. There are several kinds of adaptive beamforming algorithms for narrow band, but alittle method such as method of signal processing in the frequency field for broadbandadaptive beamforming. In application of requirements for5%of the relative bandwidth range,this paper focuses on the uniform linear array and uniform circular array with thecharacteristics of non-sensitive to the frequency.Then, this paper analyzed hardware implementation for the broadband beamformingsystem and finally a DSP+FPGA structure is chosen for signal processing. It is usedintensively for the reasons such as taking account of the data processing and parallelism. Thispaper used the latest TMS320C6455devices of TI as well as XC6VLX240T of Xilinx todesign the hardware system and basic function of DSP and FPGA was tested. Finally, thispaper completed hardware implementation for broadband beamforming.At last, from the view point of array formation, this paper introduces a uniform circulararray to realize broadband digital beamforming algorithm in detail. With the characteristics of non-sensitive to the frequency, circular array only needed a set of weights in order to achievebroadband beamforming. Then this paper gave out solving steps of optimal weighted valuebased on array comprehensive method and the calculation method of total output power of anarray to estimate interference direction. Next, this paper summarized the whole steps ofadaptive beamforming featured in broadband signal processing and the specific function ofeach module. Finally, simulation result by the constraints of FPGA program timing for themain function modules is given and it shows system meet the design requirements. |
