Signal Processing of full digital B-ultrasound (1)

Abstract: full digital B-ultrasound is the development direction of ultrasound medical instruments. Its basic technical feature is to use digital hardware circuits to achieve real-time processing of ultrasonic signals with extremely large data volumes. The development direction and main signal processing technologies of full digital B-ultrasound are outlined, including dynamic filtering, logarithm amplification, envelope detection, and secondary sampling, this article introduces the methods used in various stages of signal processing at home and abroad.

The key technologies of fully digital B-ultrasound include dynamic focus and full digital beam formation, and early digital analog signals.

Beam FormationThe main function is to calculate the delay of the received multi-channel Ultrasonic Echo Signal. Different channels can receive the focused ultrasonic echo signals through different latencies.Latency precisionIt is the core element for determining the ultrasonic beam quality and even the image quality. The latency methods can be divided into analog latency and digital latency. The traditional Analog Delay uses a trash delay line and a analog switch to control the echo signals of each channel. It is bulky and not easy to integrate. Therefore, the reliability and controllability are extremely limited. The performance of digital latency depends largely on the speed and integration of digital devices.

Figure 2 shows delayed focus. Ultrasonic Echo signals are received through multiple channels because the positions of elements in the receiving channel are different. The latency between the arrival of the same ripple is different. Digital Wave
The task of beam formation is to extend the echo signals of different channels. The echo signals of the same point are added in the same phase, the signal-to-noise ratio of the added-wave signal is called the receiving focus. The receiving focus changes with the depth, and the delay time changes with the depth of the dynamic state as the dynamic from-state focus. Add the echo signals of multiple channels to the airspaceTo match the filtering results, the signal-to-noise ratio of the High-echo data is weighted variation (amplitude variation ).