Design And Implementation Of Gyrotron Travelling Wave Tube Detection Signal Acquisition And Processing System

Gyrotron traveling wave tube(gyro-TWT)is a kind of vacuum device which works in millimeter wave and submillimeter wave band.It is widely used in wireless communication,high resolution radar and electronic warfare.Gyro-TWT must be tested at high frequency before delivery to customers to ensure that gyro-TWT can work continuously and stably for several hours under specified or optimal characteristic parameters.The existing high frequency test system can test the saturation output power characteristics by observing the waveform of cyclotron travelling-wave tube detection signal and the typical high frequency test system adopts the oscilloscope with large volume and high price to collect the gyro-TWT detection signal,which is not good for the miniaturization and integration of the system.And the oscilloscope is limited by the length of the time base of the instrument itself,only a few cycles of the detection signal can be displayed on the screen,which is not conducive to the high efficiency debugging of characteristic parameters.In addition,the detection signal will be affected by noise and cause signal fluctuation,which makes the saturated output power characteristic results obtained by high-frequency debugging inaccurate,and makes the gyro-TWT unable to give full play to its maximum performance and even causes damage to the gyro-TWT.Therefore,it is necessary to design a gyro-TWT detection signal acquisition and processing system which can solve the above problems.This thesis designs a gyro-TWT detection signal acquisition and processing hardware system that integrates signal conditioning,signal acquisition,data processing and transmission and realizes the acquisition of detection signals with different frequency and duty cycle.At the same time,the collected detection signals containing noise are denoised based on FPGA.The denoising algorithm adopts the wavelet threshold algorithm and LMS algorithm.Besides,the threshold function of the wavelet threshold algorithm is optimized for the characteristics of the detection signal.The simulation results show that SNR and MSE are optimized by 21.55% and 47.86%respectively which performance is better than the traditional soft and hard threshold function processing effect.Finally,the thesis implements the wavelet threshold denoising module using Haar wavelet basis function,two-layer decomposition layer number,Visu Shrink threshold and self-defined threshold and other modules on FPGA which realizes effective denoising processing for detection signals.The final test result of the system shows that the acquisition link of the signal acquisition board can normally collect and transmit the detection signal to FPGA.The control and algorithm functions realized by FPGA are verified,and the detection signals can be collected,processed and transmitted in the actual working environment.The system has the advantage of low cost,strong portability and noise reduction for the detection signal of cyclotron travelling-wave tube which has great engineering value and significance.