Recording shielding testing system based on ultrasonic transducer

Information security plays an increasingly important role in various fields of society, making it a widely researched topic. This paper proposes an innovative recording masking testing system to address urgent issues in the field of information security - avoiding the leakage of voice information. The system is based on STM32F407 microcontroller and integrates key circuit modules such as ultrasonic transducer, TPA3138D2 power amplifier, attenuation circuit, VCA821 automatic gain control amplification circuit, DDS, etc. The system uses DDS to generate sine wave signals and drives ultrasonic transducers to generate shielding signals. The microcontroller accurately detects audio signals through an external clock counting method. When no voice signal is detected, the signal generator automatically stops and the indicator light goes out; When a speech signal is detected, the built-in ADC module is used to sample the signal and control the DDS to adjust the sine wave output to control the power output. In addition, the system is equipped with a human-computer interaction interface that can display real-time voice detection status and control output power step size, making it convenient for users to operate and monitor. This system has lower cost, complexity, and power compared to other similar systems. After actual testing, the system has demonstrated excellent shielding performance and audio signal recognition ability, with a shielding distance of 1 to 3 meters and a shielding angle of 0 to 70 degrees, providing strong technical support for the research and optimization of recording shielding equipment.