Color Doppler ultrasound generally uses autocorrelation technology for Doppler signal processing. The blood flow signal obtained by autocorrelation technology is color-coded and superimposed on a two-dimensional image in real time to form a color Doppler ultrasound blood flow image. Usually consists of probes (phased array, linear array, convex array, mechanical fan scan, 4D probe, endoscopic probe, etc.), ultrasonic transmitter/receiver circuit, signal processing and image display.