Design And Implementation Of An Optical Transmission System Fodigital Array Radar

Digital array radar refers to a fully digital array antenna radar in which both the receiving and transmitting beams are digitally formed.A large number of digital signals need to be transmitted between the antenna of digital array radar and the signal processor,but the amount of data of each antenna digitized T/R unit is not large.This requires first multiplexing the data of multiple T/R units to reduce the number of data channels,and then multiplexing the reduced data channels for the second time.In addition,a low phase noise clock signal needs to be transmitted between the antenna and the signal processor for synchronization.This thesis mainly solves the three key technical problems of data transmission,control signal transmission and clock transmission in digital array radar,and designs a typical optical transmission system for digital array radar.Two multiplexing technologies are adopted in the system.One is multiplexing on a physical channel,that the optical signals are multiplexed by using wavelength division multiplexing technology,and the optical signals of different wavelengths are multiplexed into one optical fiber.The other is time-division multiplexing technology.According to the characteristics of radar echo data,the data of multiple front(T/R)units are multiplexed into one higher speed data by using idle time.This thesis mainly proposes an architecture for the transmission of large-capacity digital signals and low phase noise analog signals through single-core fiber.Through the research of wavelength division multiplexing technology and time division multiplexing technology,the optical transmission system for digital array radar is realized.The system mainly achieves the following indicators:Optical signals of the same wavelength are converted into different wavelengths by wave length conversion,and then the wavelength division multiplexing is performed by wavelength division multiplexing.The system has a total of 18 channels,one of which is used to transmit analog clocks,and the other channels are used to transmit digital signals.The transmission rate of each channel is 10 Gbps.At present,the system uses 4 channels,and the remaining 13 channels are used for backup expansion,and the system transmission capacity is greater than 100 Gbps.Through the use of analog optical transmission technology,the operating point of the lase is rationally configured,including power control and temperature control,to achieve low phase noise clock signal transmission,and its phase noise is less than-140dBc@1KHz.The amount of data transmitted by each T/R unit of digital array radar is not large,and is generally less than 200 Mbps.The system utilizes FPGA's powerful logic resources,internal storage and high-speed transceivers to realize time division multiplexing technology,and multiplexes data of multiple T/R units into one channel of higher-speed data.One data multiplexing unit designed in this system can multiplex 30 channels of data into one channel.Two data multiplexing units are used in this system to interface with 60 T/R units.By selecting the digital optical transceiver module at the CWDM end,requiring the optical power of the optical transceiver module to be greater than-2dBm,and requiring the receiving sensitivity to be less than-20 dBm,the dynamic range of the system is greater than 10 dB,which achieved the system's indicator.Optical transmission systems using key technologies including time division multiplexing and wavelength division multiplexing can be widely used in other digital array radars.