High-precision echo time of flight measurement method and its FPGA implementation

High-precision time measurement has been widely used in scientific experiments and industrial process control areas such as high energy physics, laser range measurement and high-precision positioning, ultrasonic flow measurement, etc. A new high-precision echo time of flight measuring algorithm is presented, which combines the pulse counting method with the phase delay interpolation. The pulse counting method is used to ensure a large dynamic measuring range, and the digital delay locked loops to improve the accuracy and reduce the counting quantization error. The phase delay interpolation is used to reduce the quantization error of pulse counting for further improving the time measurement resolution. Test data show that the system for echo time of flight measurement with this algorithm as its core and implemented on an FPGA has a shorter conversion time, and a measurement error less than 100 ps.