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The test system consists of a microcontroller (STM32F103ZET6), a temperature measurement system, an ultrasonic transmission circuit, an ultrasonic receiving circuit, and a display system. First,the square wave signal of 40KHZ is generated by STM32F103ZET6, and then it is sent to the ultrasonic transmitting probe through the signal adjusting circuit. Then, the echo signal which is collected by the ultrasonic receiving probe is shaped and sent to the MCU controller for processing to obtain the required data, and is displayed through the display module. The ambient temperature is collected by a temperature sensor, and the signal of the collected temperature sensor is processed and analyzed by the STM32F103ZET6 controller to obtain an ambient temperature, which is displayed by the display module. And at different temperatures, the measurement of the propagation speed of ultrasonic waves in air and water is achieved.