Bessel wave is a kind of non-diffraction wave in many types of ultrasonic field. In theory, it can propagate infinitely far without divergence. The non-diffraction characteristics of Bessel wave make it have potential application value. To quantitatively study Bessel wave, first of all, we need to calculate and analyze its sound field. There are many simulation methods, such as Rayleigh Sommerfeld method, finite difference time domain algorithm and so on. Generally speaking, these methods are time-consuming, computational complexity and low accuracy. In this paper, a simple method is proposed to simulate Bessel sound field by using the concept of angular spectrum. Firstly, the original angular spectrum is obtained by Fourier transform of the sound field distribution on the sensor boundary. Then, the angular spectrum distribution on any other plane perpendicular to the direction of sound field propagation is calculated according to the principle of angular spectrum propagation. Then, the field distribution on the plane can be obtained by inverse Fourier transform, and all the fields perpendicular to the direction of sound field propagation can be obtained. The results of the whole sound field distribution can be obtained by combining the field distribution of the plane. The simulation results of different methods show that this method has fast calculation speed and high simulation accuracy due to the introduction of Fourier transform. It can not only simulate Bessel sound field effectively, but also simulate other types of sound field. Therefore, the work of this paper has a certain significance for the study of non-diffraction sound field.
Ultrasound Doppler blood flow measurement is to measure the velocity of blood flow through the frequency shift characteristics of Doppler signal. It has the advantages of high sensitivity, non-invasive, strong direction and simple operation. The simulation of ultrasonic Doppler signal is an important aspect in the research field of ultrasonic Doppler signal. Computer simulation of Doppler signal can be used to evaluate the accuracy of Doppler velocity measurement method in early stage. It is an effective way to improve the accuracy of Doppler velocity measurement. Generally speaking, the theoretical model of the existing simulation method is relatively complex and the calculation amount is large. In this paper, a relatively simple simulation algorithm is proposed to simulate the Doppler echo signal in time and space domain. This method is based on the physical concept of wave front propagation. According to the time of moving object passing through two adjacent wave front with the same phase, the relationship between Doppler signal data and primary ultrasonic signal data is determined. The Doppler signal data is established by extracting the data of the primary transmitted ultrasound signal. A simple, efficient and intuitive simulation algorithm of Doppler echo signal is realized. The experimental results show that the simulation results are consistent with the theoretical calculation. It can more intuitively simulate the characteristics of real Doppler signals, accurately simulate continuous wave Doppler signals and pulse wave Doppler signals, and provide an effective and reliable signal source for Doppler signal analysis and processing methods.