Method and device for extracting maximum frequency from spectrogram

Abstract

The invention relates to the technical field of ultrasound and specially relates to the technical field of Doppler ultrasonic measurement of flow of fluid, in particular to a method and a device for extracting maximum frequency from a spectrogram. According to the method and the device, disclosed by the invention, the maximum frequency can be obtained in a simple way against frequency spectrum data under strong noise and weak noise. On the basis of a geometric method, interference caused by larger noise points can be resisted under the strong noise, weak signals can be effectively detected under the weak noise, and the loss of signals can be avoided.

Description

technical field [0001] The present invention relates to the technical field of ultrasound, in particular to the technical field of ultrasonic Doppler measurement of fluid velocity, in particular to a method and device for extracting the maximum frequency of an acoustic spectrogram. Background technique [0002] Ultrasonic Doppler technology is widely used in the clinical diagnosis of human blood flow conditions due to its non-destructive nature, and many diseases can be reflected from the maximum frequency curve of the ultrasonic Doppler signal. When Doppler technology is applied clinically, the frequency spectrum of the obtained blood flow signal is first analyzed to obtain the spectrogram, and then the spectrogram is used to calculate the spectrogram parameters used for diagnosing vascular diseases, such as S / D, RI, PI, etc. . The estimation of the maximum frequency is the basis for calculating the Doppler parameters. In order to obtain a small error, the maximum frequenc...

AI Technical Summary

Problems solved by technology

The three-line fitting method was proposed by Wang Yuanyuan in "Estimation of the Maximum and Minimum Frequency of Pulse Doppler Signal" in 1998. Three straight lines are used to fit the integrated power spectrum curve. The two intersection points are the maximum and minimum frequencies respectively, but due to the middle A straight line is not enough to fit wideband signals, and only has high estimation accuracy for narrowband signals

This method is similar to the geometric method, looking for the maximum value of the integrated power spectrum curve minus the noise threshold, which can detect weak signal edges, but is not robust to large speckle noise

[0006] In the technical solution disclosed in Chinese patent CN200510036372.0, a method of automatically updating the noise threshold according to the historical noise level and the current noise level is proposed. Spectrum locates the maximum frequency, but the method of initializing the noise threshold is not clear, and it is difficult to initialize the noise level without increasing the amount of calculation in actual operation

[0007]The disadvantage of the above method is that there is no robust maximum frequency curve extraction method for the spectrum with strong noise and weak signal

Images