Design And Implementation Of Digital Phase Measuring Instrument Based On FPGA

With the rapid development of electronic information technology,phase measurement technology as a very inportant means of signal feature detection has received increasing attention from researchers.At present,the measurement accuracy of the self phase measuring instrument in the domestic market is low and the type are few,which has gradually been unable to meet the practical engineering application needs.Based on this situation,a phase measuring instrument based on FPGA has been designed in this paper.The phase measuring instrument has two functions:generating two sinusoidal signals with the same frequency and adjustable phase difference,and measuring the phase difference between two channels of the same frequency sine signal.First of all,this article introduces the implementation principle of the same-channel phase-difference adjustable signal generator implementation scheme and the two-channel same-frequency signal phase difference measurement often used in the current project,and their deficiencies;then it proposes this system implementation scheme.One FPGA controls a dedicated DDS chip with high degree of integration and phase-shift accuracy of 0.022°to generate two sine wave signals with the same frequency and adjustable phase difference,and controls a 16-bit synchronous acquisition ADC chip AD7606 to perform data acquisition on the dual-channel sinusoidal signals.The collected data is logically operated in the FPGA to complete the phase difference measurement function.Second,the paper introduces the hardware modules of the system in detail,then uses the hardware description language to implement the logic functions of each part of the FPGA,and focuses on the difficulties in each logic function.The system uses the mature open-source graphical interface framework QT to write the system’s host computer software.The host computer software will use the 3σ rule and the mean filter rule to remove the measurement data after the coarse measurement value and display it in a real-time manner in a curve graph manner.Finally,on the basis of completing the software and hardware design and debugging of each module of the system,the overall functional verification test of the system is performed with the corresponding instrument.The results show that the frequency stability of the tunable sinusoidal signal with the same frequency phase difference can reach 10-4 level,the phase difference accuracy is within ±0.10,and the preset phase difference of the two-channel sine wave signal at the target frequency point is measured,and the measurement result is analyzed.The zero-phase-determined coarse measurement accuracy can be achieved ±0.5°,the correlation function method and Fourier transform method measurement accuracy can be achieved ±0.1°,and all the functional accuracy indicators meet the expected design goals.