The dynamic filter is an important part of the entire Veterinary Ultrasound system, which directly affects the resolution of the echo signal at the full detection depth. By analyzing the attenuation of ultrasound in the human body, it was found that a dynamic filter with coefficients that vary over time must be utilized, which led to the concept of dynamic filters and the variation law of filter coefficients.

There are various types of veterinary B-ultrasound probes, and there are currently multiple classification methods. According to the working principle, probes are divided into pulse echo type and Doppler type. The commonly used linear array, convex array, mechanical fan scan, and phased array probes all belong to pulse echo probes, which use pulse waves to achieve two-dimensional scanning of animal tissues and organs.

As the frequency of ultrasound increases, the attenuation coefficient of the medium on ultrasound energy also increases. Therefore, when the emitted ultrasound has a wide frequency band, the frequency components in the received echo are inevitably related to distance. In the near-field, the echo frequency components are mainly concentrated at the high end of the frequency band. As the detection depth increases, the echo frequency components gradually shift towards the low end of the frequency band. This is because as the depth increases, the attenuation of high-frequency components is greater than that of low-frequency components,

When the detection depth is large, high-frequency components cannot even reach the deep part of the medium and are completely absorbed. Therefore, the valuable components in the near-field are high-frequency components, while low-frequency components are near-field echoes. The excessive occupation of low-frequency components can seriously affect the resolution of the near-field, so filtering should be considered; What is valuable in the far field are the low-frequency components, and the valuable high-frequency components have already been attenuated and should be filtered out.

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