Digital Implementation Of Parallelism Multi-beam Reconnaissance For Wideband Radar

Electronic warfare has become an important part of modern and future wars.Whoever can monitor and control the spectrum resource in real time will be able to obtain more priorities in the wars.As an essential part of most current electronic warfare systems,the reconnaissance receiver plays a crucial role in the interception and detection of radar signals.In this paper,the following research contents are conducted about the principle and design of parallelism reconnaissance receiver for wideband radar.(1)Based on the theory of wideband beamforming,a parallelism receiving method for wideband radar signal beams with different directions in the complex electromagnetic environment by using array antennas is researched.Then,the purposes of multi-beam and multi-direction parallelism reconnaissance are achieved.At the same time,the method also improves the signal-to-noise ratio of the received signals and suppresses the interference.(2)In the fractional delay compensation part of broadband beamforming,an implementation method of the fractional delay compensation filter is proposed based on Lagrange interpolation algorithm and parallelism filter theory,which can be applied to the input data with features of parallelism and multi-channel.After processed by the cache and speed reducer,the high-speed serial data stream from analog-to-digital converter will be changed into low-speed parallelism and multi-channel data streams.The problem of fractional delay compensation for the output data streams from the cache and speed reducer has been successfully solved with this method.(3)The theory of digital channelization is deeply studied.The relationship between overlapping mode of sub-channels’ transition zone and the ratio of sub-channels’ number with decimation factor is discussed.The design method of the prototype low-pass filter under the optimal overlapping condition of sub-channels’ transition zone is given as well.Simultaneously,this thesis implements an efficient structure of digital channelization by taking advantage of variable substitution method and multi-channel filter theory.Compared with the traditional one,this structure reduces about 50% of the hardware resource consumption.In order to improve the efficiency of multipliers and reduce the resource consumption,time division multiplexing method and pipeline processing technology are employed to implement the modules of multi-channel filter bank and inverse fast fourier transform in the efficient digital channelization structure.(4)The output data from digital channelization is detected by means of multi-point energy accumulation and finite state machine.As a result,the measurement error due to the truncation of channels can be avoided in this way.In case of the false alarm caused by the signal frequency crossing channels,a signal processing and detecting approach with two-levels of digital channelization is proposed.Signal detection results of the second level are used to discriminate the pulse descriptive word obtained from the first level,which removes the false signal and significantly reduces the false alarm probability of the receiver.