Dayu Electronics: Algorithm Implementation for Waveform Reading of Ultrasonic Depth Sounder Transducers
The working principle of Dayu Electronics' ultrasonic depth sounder is based on the propagation and reflection characteristics of sound waves in water. The transducer emits an acoustic pulse toward the water bottom, and the pulse is captured by the receiving transducer after reflecting off the bottom interface. The core formula for water depth calculation is Z=Vt/2, where V is the propagation speed of sound in water, and t is the round-trip time from transmission to reception. Therefore, precise measurement of time t is key to ensuring measurement accuracy. The starting point of time t is exactly the start of the transmitted waveform, and the end point is the arrival time of the characteristic feature in the echo signal.
Technical Challenges and Solutions for Waveform Start Point Determination
In practical applications, factors such as ambient noise, scattering from suspended particles in the water, and the complexity of the bottom topography cause the echo signal to be mixed with volume reverberation, background noise, and other interferences. The traditional fixed-level threshold method is simple and real-time, but it is prone to false or missed detections in complex environments, and its accuracy is limited.
The core of Dayu Electronics' solution lies in advanced backend software algorithms. As our technical team has stated, the feature-based method is one of the mature and efficient approaches. This method precisely locates the echo by analyzing the waveform characteristics of the received signal. For example, it can compare A/D sampling points point-by-point to find the feature waveform with the maximum amplitude, and then determine the zero-crossing point of that feature waveform as the time end point. The start point of the ultrasonic transmission time can be precisely determined as the zero-crossing point of the last wave in the transmitted signal waveform.
In addition to the feature-based method, several other high-precision algorithms are available in the industry for reference and integration:
1. Cross-correlation algorithm: This method uses the cross-correlation function between the transmitted signal and the echo signal for detection. When an m-sequence code with sharp two-level characteristics is used for driving, its autocorrelation function approaches a delta function, providing good range resolution and thus accurately determining the echo arrival time.
2. Wavelet transform method: This method analyzes transient and singular points in the signal. By constructing a specific wavelet base and performing convolution transformation with the sampled signal, it can more precisely capture the arrival time of the echo signal. It performs better than the traditional threshold method, especially in environments with severe noise interference.
3. Square-law detection method: In shallow-water depth measurement, processing the echo signal with square-law detection can filter out clutter while determining the depth characteristics of the target area.
Dayu Electronics has deeply integrated these algorithmic concepts into the R&D of its depth sounder products. Our backend processing system can intelligently select or fuse the most appropriate algorithm for waveform start point determination based on different hydrological conditions and measurement requirements. We place great emphasis on the reliability and robustness of algorithms. Some basic algorithm modules reference widely validated open-source programs, and on this foundation we have carried out extensive engineering optimization and scenario adaptation, ensuring stable and accurate water depth data in complex waters such as rivers, lakes, reservoirs, and even ports and docks.