Research On Hardware Implementation Method Of Array Ultrasonic Signal Sparse Sampling Based On Finite Rate Of Innovation

Ultrasonic array detection technology has been widely used in industrial and medical fields due to its high scanning efficiency,rich information on defects,and easy imaging.However,with the development of array detection technology,problems such as large amount of data collected are becoming more and more prominent,which makes it difficult to transmit,collect,store,and post-process signals.Nyquist conventional data sampling is based on the integrity of the frequency information,which is ensured by the denseness of the sampled signal in the time domain,so the amount of data collected is large,more over the frequency of the ultrasonic signal is high,the massive data generated during test severely restricts the development of ultrasonic testing technology.The sparse sampling theory based on the Finite Rate of Innovation(FRI)has received extensive attention in recent years.But both theoretical research and physical circuit implementation methods are directed to single-channel ultrasound signals,no further research on FRI sparse sampling of ultrasonic sensor array.If the single-sensor sparse sampling circuit is superimposed to achieve the sparse sampling of the array signal,the circuit system will inevitably become too complicated and huge.To this end,the thesis constructs an array ultrasonic FRI sparse sampling framework based on synthetic shared sampling kernel.After study the framework theoretically,we propose an array pulse synthesis method based on positive sequence rules and an array pulse synthesis signal FRI sanpling kernel based on elliptical lowpass filter.The array sparse sampling hardware circuit based on the framework is designed and fabricated,and the feasibility of the method is verified by simulation and experiment.The experimental results show that the method can effectively reduce the complexity of the array signal FRI sampling system and reconstruct actual array pulse separately from the obtained single-path sparse data.The main research contents of the thesis are as follows:(1)Based on the analysis of the domestic and foreign research status of sampling theory,the related theories of FRI sampling are briefly introduced.The implementation principles of two typical FRI sampling frames are analyzed.Several common FRI signals and FRI sampling kernels are listed.Based on this,an FRI model of single-shot and multi-receiver array ultrasound signals is established,and an FRI sampling frame for array ultrasound signals based on synthetic shared sampling kernels is constructed.(2)Based on the theoretical derivation,an array ultrasonic pulse stream acquisition framework based on quadrature demodulation is constructed.An array pulse synthesis method based on positive sequence rules is proposed.And by analyzing the arrival time of the array detection echo signals,the method of determining the minimum delay time of array pulse in two ways of incidence is given.The FRI sampling preprocessing hardware circuit of array ultrasonic signal is designed and fabricated,and the circuit performance is verified by experiments.(3)The FRI sampling kernel implementation method of array pulse stream synthesis signal based on Fourier coefficient is proposed after comprehensively analyzing the characteristics of the array pulse stream synthesis signal and the existing types of sampling kernels.The FRI sampling kernel based on Elliptical-LPF is designed.According to the characteristics of the array pulse synthesis signal,the selection basis of the sampling kernel parameters is analyzed,and the reconstruction performance of the sampling kernel under noise is verified by simulation experiments.Finally,the sampling kernel circuit is designed and fabricated.(4)According to the FRI sampling frame of array ultrasonic signal,the hardware system of FRI sparse sampling of single-shot and multi-receiver array ultrasonic signals and its overall working sequence are designed.Then the array transducer transceiver circuit is designed,and FRI sampling of array ultrasound is realized on hardware.(5)The array ultrasonic sensor defect detection platform is built.In the actual test,a single sampling kernel and data acquisition channel are used to achieve the sparse sampling and reconstruction of 8 array detection signals with 4 MHz center frequency at rate of 850 kHz.Compared with multiple single-channel sparse sampling hardware superposition methods,the hardware complexity of the sampling system is reduced,and the amount of data collected is further reduced.