Design Of Uniform Circular Phased Array Based On VxWorks And FPGA

Uniform circular array which is widely applied on sonar system is a kind of array form.It is facile to get redeeming delay time on circuit for the more uniform beam in different direction,and can only form the specified directivity under the circumstances of redeeming by electric delay.The item uses phased array technology.It adopts special calculator FPGA to delay time which is made by forming beam through real time controlling nodes,and make different phased vibrating wave.It can form wavy plan through theory of wave intervening in the scanning direction.In this paper,it simulates the directivity curves of forming beam,analyzes height of minor lobe and width of main lobe, and calculates the delay time of projecting nodes with MATLAB,establish academic base. The error required is less than one microsecond.Digital controller chooses eight nodes from eighteen to form beam between zero degree and three hundred and fifty-nine degree and delay the time of projecting beam.It can produce four modes which is A,B,C and D, and the minimum direction of scanning beam is five degree.The design of FPGA uses such a mode that combines schematics and VHDL,which is not only saving the number of logic units in FPGA,improving the utilization efficiency,but also enormously shortening the period of development.VxWorks which is real time system output the value of direction degree on the screen,making a function of real time watch.The results of simulation show that the design of uniform circular array with eighteen nodes based on FPGA is very available.In the different output of direction,signal pulse is stabilized with small error.It is provided with the characteristics of high delay accuracy, fast modulating phase and strong resisting disturbance,etc.The paper establishes the mathematics model of circular array in the foundation of design requirement,which draw the graphics of directivity curves with MALTLAB tool,and intuitively simulate the delay time of all the nodes with one microsecond precision.The directivity of forming beam are prominent,the width of main lobe is distinct,and producing wavy plan with more powerful, which make for scanning in space.Analyzing the delay error,mention tow improved plans. First,improving the delay precision by enhance the delay precision of FPGA to 0.5 microsecond.Second,discarding the node of maximum error,we can select one of them according to real situation.