Design And Implement Of Fiber-optic Preprocessing Board For Ship-borne Fire Control Radar

With application of Beam Forming technology,phased array radar can scan beams fast and easily realize the low side-lobe and beam-shaped antenna patterns.Compared with conventional radar,phased array radar has been greatly improved in the performance of multi-object detection and tracking precision and capability of anti-interfere.At the present time,conformal array radar has already become the main development direction of phased array radar.Due to the characteristic of conforming to a prescribed shape,conformal array radar can utilize the surface area of the carriers effectively.Conformal array radar not only has a good aerodynamic performance,but also can save the carrier space and simplify the installation.So the conformal array radar is widely applied in the fields of reconnaissance,communication and navigation etc.This paper proposes design methods about realizing the low side-lobe of the sum and difference beam and the adaptive side-lobes cancellation,which is based on a ship-borne bended surface conformal phased array radar.Then project development and implementation of digital beam forming algorithm are carried out on this radar by expounding the design methods.Firstly,this paper introduces the basic principle of digital beam forming,and the sum and difference beams of uniform polygonal linear array and circular array are optimized by using the convex optimization,so that the arrays can generate the low side-lobe of the sum and difference beam patterns and weak the interference in the required direction,at the same time,the optimized angle error curve is consistent with the original angle error curve,which has no affection with the angle measuring performance.Then deduces the beam forming formula of a bended plane array,and proposes a method about forming low side-lobe sum and differential beam patterns based on the form of a two-stage weighted theory.Next,the corresponding simulation system model is established and the simulated program is validated by MATLAB simulation.According to the principle of adaptive sidelobes cancellation,a scheme of adaptive sidelobes cancellation is proposed based on a bended plane array and the performance of cancellation is analyzed with simulation.Secondly,according to the methods about realizing the low side-lobe of the sum and difference beam and the adaptive sidelobes cancellation,this paper designs and implements the digital beam forming system of a ship-borne bended surface conformal phased array radar.Through the analysis of the ability of data throughput and signal processing capabilities,a FPGA and DSP-based hardware processing platform was determined.With the part of peripheral circuit in the design,such as the power,clock,communication interface,etc.,we got the hardware platform meeting the requirements of the digital beam forming system.On this hardware platform,in accord with the design requirements we divide the function modules of the system,includes the data communication module,the beam forming module the calibration module and so on.The tasks and implementation of each functional module is analyzed and the compiling and debugging of the corresponding program is completed.Then each functional module of the system was simulated by software and tested online by using some test data,in order to verify the feasibility and correctness of the system design.Finally,this paper analyzes the problems of bit errors and lost packets when data is transmitted by fiber and link ports during the system intermodulation and proposes some corresponding solutions.For the problems of bit errors and lost packets when data is transmitted by fiber,this paper proposes some solutions,includes,using pre-weighted technology at the transmitter,increasing the equalizer in the receiver to compensate channel properties,extending the elastic buffer.For the problems of bit errors when data is transmitted by link ports,this paper proposes some solutions,includes,carrying on the timing and location constraints,setting the Frame Reset feature,which can reduce the rate of error codes from the data transmission and enhance the stability of the system.