Digital ultrasonic transcranial Doppler digital demodulation signal processing method and device

Abstract

The invention discloses a digital ultrasonic transcranial Doppler digital demodulation signal processing method and device. The method comprises the following steps: performing the A / D (analog / digital) sampling on an input frequency-modulated wave which is a non-demodulated ultrasonic echo signal, and then performing the amplitude limiting through a digital comparator; detecting a modulation signal reflected on the frequency conversion in a frequency-modulated save subjected to the amplitude limiting; and taking the absolute value of the modulation signal, responding the changes of the amplitude of the modulation signal to an envelope line, and acquiring a low-frequency modulation signal through a down-sampling low-pass filter. The device comprises an AD converter, at least two large-capacity high-speed caches FIFO (first in first out), a DSP digital signal processor), and an FPGA (field programmable gate array). According to the invention, the wide frequency band scanning and the full-depth scanning can be realized, the timeliness and signal-to-noise ratio (SNR) of the system are improved, a blood flow dynamic parameter is accurately extracted, the SNR of a detecting signal is improved, and the quality of a frequency spectrum image is improved.

Description

technical field [0001] The invention belongs to the field of high-precision and intelligent detection in medical equipment, and specifically includes high-speed signal collection and processing, high-precision, intelligent signal detection and analysis. Background technique [0002] Ultrasonic transcranial Doppler system is currently an important electronic medical instrument system for cerebral blood flow detection and brain disease analysis. It is mainly composed of transducers, ultrasonic conversion analog circuits, digital signal acquisition systems, data analysis systems and software systems. composition. [0003] During the propagation of ultrasonic waves, when encountering a moving object, the frequency of the reflected wave will change, and the magnitude of the frequency change is proportional to the moving speed of the object. This principle can be used to measure the blood flow velocity and dynamic characteristics of human brain vessels, which is the theoretical b...

AI Technical Summary

Problems solved by technology

At present, the method used to process Doppler data is short-time Fourier transform. This method increases the sidelobe effect of the blood flow spectrum, thereby affecting the measurement accuracy. It is difficult to accurately judge the condition of the tester

Due to the limitations of high-speed signal acquisition and real-time processing technology, there is no full-depth digital ultrasound transcranial Doppler system yet

The signal sampling speed required by digital transcranial Doppler is at least 120 times that of the analog transcranial Doppler system, and the frequency shift demodulation is converted from the original analog demodulation to real-time digital demodulation, and the demodulation accuracy must be guaranteed, and the algorithm is difficult increase

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