In the early 1990s, portable phones were all the rage. As laptops shrink in size, they are also known as "backpack phones." At present, the electronics industry has made great strides. Today's mobile phones can send e-mails and text messages, take photos, check stock prices, schedule meetings, and of course, talk to anyone in the world. Also in the medical field, previously known portable ultrasound systems are loaded on carts and can be towed, but in reality they are difficult to tow. Fortunately, the ultrasound system is also constantly improving, and is called "new stethoscope" by doctors. This article reviews the classic ultrasound signal links, discusses the different system partitioning strategies and their advantages and disadvantages, and demonstrates the implications of these system partitioning strategies in portable ultrasound applications. Ultrasonic signal link Figure 1. Typical ultrasound signal link Figure 1 shows a simplified schematic of an ultrasound system. The sensors of the system are located at the end of a relatively long cable, which is about two meters long. These cables contain at least 8 to 256 miniature coaxial cables and are among the most expensive components of the system. In almost every system, the cable is driven directly by the sensor unit. The capacitance of the cable becomes a load on the sensor element, causing a large signal loss, which imposes sensitivity requirements on the receiving end in order to maintain dynamic range and achieve optimal system performance. At the transmitting end (Tx path), the beamformer determines the delay mode and pulse sequence, which is set for the desired focus. The high voltage transmit amplifier that drives the sensor then amplifies the output of the beamformer. These amplifiers can be controlled by a digital-to-analog converter (DAC) or a high-voltage FET switch array to shape the transmit pulses for better energy transfer to the sensor unit. At the receiving end, a transmit/receive (T/R) switch (usually a diode bridge) blocks the Tx high voltage pulse. The use of high voltage (HV) multiplexers/demultiplexers in some arrays reduces the complexity of the transmit and receive hardware, but at the expense of flexibility. The Time Gain Control (TGC) path consists of a low noise amplifier (LNA), a variable gain amplifier (VGA), and an analog-to-digital converter (ADC). Under the control of the operator, the TGC path is used to maintain image uniformity during the scan. Good noise performance depends on the LNA, which reduces the contribution of the back VGA to noise. For applications that benefit from input impedance matching, active impedance control optimizes noise performance. The wide dynamic range input signal is compressed by VGA to meet the input range requirements of the ADC. The LNA's conversion to the noise at the input limits the minimum input signal that can be resolved, and the noise that is converted to the output depends primarily on the VGA, which limits the maximum instantaneous dynamic range at a particular gain control voltage. This limit is set based on the quantized noise floor, which is determined by the resolution of the ADC. The anti-aliasing filter (AAF) limits the signal bandwidth while also limiting other noise in the TGC path before the ADC. Beamforming of medical ultrasound is defined as the phase alignment and summation of the signals generated by a common source but received by the multivariate ultrasound sensor at different points in time. In the CWD path, the receiver channels are phase shifted and summed to extract consistent information. Beamforming has two functions: one is to indicate the direction to the sensor, ie to increase its gain, and the other is to define the focus in the human body from which the echo is located. Fruit and vegetable powder is the fresh fruits and vegetables through the international advanced level of freeze-drying technology and equipment, after pretreatment, quick-freezing, vacuum drying, ultraviolet sterilization, packaging storage and other more than 10 processes. Fruit And Vegetable Powder ,Wheat Straw Juice Powder ,Alfalfa Juice Powder,Celery Juice Powder Xi'an Double H Health Technology Co., Ltd , https://www.xahnhcj.com