The Study Of Measuring Distance Precisely By Ultrasonic

The technology of measuring distance by ultrasonic signal is widely used in many social fields, such as backing -car radar and so on, but their precision is relatively low. At present, the request for high precision measuring distance system becomes stronger and stronger. So, grounding on the comprehension of measuring distance principle by ultrasonic, the paper completes an hardware design which based on time difference measuring distance theory , and presents a peripheral extended counting circuit of single-chip computer , which can increase the counting reference frequency so as to improve measurement accuracy of the system.In order to improve the measurement accuracy and system stability further, we add a temperature sensor in the hardware design and adopt the improved method which combines sound velocity presetting with medium temperature measurement to mend the sound velocity. By this means, the influence of temperature variation on distance measurement is decreased. In addition, in order to improve the system reliability in time counting, we adopt CPLD chip to realize the counting function in the design.In the end, on account of that ultrasound can be corrupted easily by Gaussian noise, a kind of algorithm based on Phase-shift detection is discussed, which can suppress the interference efficiently and be helpful to improve the measurement accuracy.