Research On Signal Detection Algorithm Of Bridge Vibration Radar In Range Doppler Domain

Radar has become one of the most important tools in the field of bridge health detection,mainly because of its non-contact,high precision,and continuous detection,comprehensive detection and other advantages,radar detection of bridge health mainly through the vibration signal generated by the bridge For analysis,since the radar signal contains phase information,it is convenient to extract the deformation variable.The detection of traditional bridge radar vibration signals usually requires deformation inversion of the original signal,and then the vibration signal is detected on the inversion signal,but the bridge vibration signal is usually in a complex environment,under the influence of clutter and noise,the inversion signal is difficult to show the characteristics of the vibration signal itself,and it is not easy to detect.Some clutter filtering methods will reduce the energy of the weak vibration signal and increase the detection difficulty.In view of the above problems,this paper detects the vibration signal from the characteristics of the vibration signal itself,and processes the signal in the range Doppler domain.In the range Doppler domain,the signal will be accumulated,which improves the signal-to-noise for the vibration signal.Compare.In this paper,two algorithms are proposed to adapt to the detection of vibration signals under different environmental conditions.In the frequency detection algorithm,the basic idea of the two detection methods is the same.First,the range unit is detected in the range Doppler domain,and then the frequency of the vibration signal is detected based on the characteristics of the vibration signal itself.The method in this paper directly detects the frequency of the radar signal,which reduces the error caused by the inversion of the deformation variable.The main research work is as follows:(1)In view of the problems that the existing methods need to filter the original echo signal,deformation inversion,etc.,which will affect the detection results,this paper directly starts from the characteristics of the vibration signal itself,and analyzes the vibration signal according to the characteristics of the vibration signal itself.its detected.Firstly,the signal model of the vibration radar signal is established,the variables in the signal model are analyzed,and then the vibration signal is simulated.By setting certain parameters,the simulation model of the Doppler frequency and deformation inversion of the vibration signal is simulated.In the Doppler frequency simulation model and the deformation inversion model,it can be observed and analyzed that the vibration signal has the characteristics of multiple harmonics and periodicity.The theory that the signal-to-noise ratio is relatively improved and the vibration signal is easier to be detected in the range Doppler domain is proposed,and the simulation verification is carried out,which provides theoretical support and detection environment for the subsequent vibration signal detection.(2)Aiming at the problem that bridges are usually in a complex environment,the signal-to-noise ratio is low and the clutter is strong,it is difficult to detect the vibration target position.This paper proposes a CA-CFAR-based bridge vibration target position and frequency detection algorithm.CA-CFAR is a unit average constant false alarm detection algorithm,which can automatically adjust the detection threshold according to the average power in the sliding window,which is suitable for the environment with low signal-to-noise ratio.The detection of the vibration target position and the fundamental frequency of the vibration signal is well completed in the environment.(3)Since the radar signal has side lobes,the detection results usually appear false alarms,resulting in inaccurate detection results.Therefore,this paper proposes a bridge vibration target position and frequency detection algorithm for secondary peak detection.It is necessary to set the detection sliding window,which reduces the difficulty of the algorithm.The unit at the detection position itself is compared with the two units before and after,and two detections are performed to complete the screening of the peak points.The second detection can solve the existence of side effects.There is a problem of false alarms in the flaps.After the simulation and the test of real data,the algorithm can accurately complete the detection of the target position and fundamental frequency of the bridge vibration.