Research And Implementation Of High-Resolution Short Intervals Measurement Based On FPGA

Time interval measurement has been widely used in many areas, such as navigation and positioning, aerospace, communications, electronics, astronomy, metrology, electronic technology. With the technology development in these areas, accuracy of time interval measurement has been proposed higher requirements.In this paper, the equivalent pulse-counting method is proposed based on pulse-counting method. Its principle is that: firstly of all, several count clock signals of relative phase shift are obtained by multiplying and shifting the phase of the original count clock signals. Then count the interval gate signal used these clock signals. Finally the measured time interval gate signal is obtained by the sum of the value of counters. However, in the equivalent pulse-counting method, in order to obtain these signals, several PLL often are taken. So in order to reduce the number of PLL, the improved Equivalent pulse-counting method is proposed in view of the internal structure of the FPGA. Its principle is that: firstly, several gate signals which phase followed by a difference ofτare obtain by delaying the original gate signal. Then use PLL to multiply the frequency of original clock signals, then use these signals to count each of gate signal. Finally, measured time interval gate signal is obtained by the sum of the value of counters.In this paper,the software and hardware achieved of equivalent pulse counting and improved equivalent pulse-counting method are described in detail. Software implementation is used hardware description language Verilog to program. Hardware implementation includes FPGA and its peripheral circuits and microprocessor and its peripheral circuit design. The experiments prove that Improved Equivalent pulse- counting method has some advantage to Equivalent pulse-counting method based on FPGA. The time interval measurement system based on the improved equivalent pulse counting method can achieve a resolution of 400ps. Measurement time range of up to 1100s. Used FPGA as the core chip, the system is stability and reliability and simplified in circuit design. With the development of microelectronics technology also Improved Equivalent pulse counting method has room for improvement.