Research On High Precision Time-interval Measurement Based On Band-pass Filter

Time interval measurement is widely used in daily life,industrial production and defense aerospace.In particular,picosecond time interval measurement plays an extremely important role in high-precision scientific research,such as precision instrument manufacturing,lidar speed measurement,missile guidance and high-altitude communication.With the advancement of science and technology and the continuous improvement of the industrial level,the demand for measurement accuracy of time interval measurement has also been improved continuously.How to further improve the measurement accuracy of time interval measurement has been an urgent problem to be solved.Due to factors such as measuring equipment and measurement methods,picosecond time interval measurement has not yet matured,and there is much room for research and development.Based on the time interpolation method,a high-precision time interval measurement method based on band-pass filter is studied.Based on this,a measurement system is designed to realize the measurement of the picosecond time interval.The time interval measurement method in this paper can be used to measure the time interval between two event signals.The measurement idea is: the event signal is converted into a narrow pulse signal by a conversion circuit capable,which could accurately detect the trigger edge of the event signal.And then let the pulse signal pass through the amplification shaping circuit and the bandpass filter,so the pulse signal is converted into an envelope signal with a certain time width,thereby stretching and expanding the sampled data.The envelope signal is then sampled,stored,and transmitted by a high speed ADC and FPGA.Finally,the sample response reconstruction and the secondary correlation operation are performed on the sampled data,and the corresponding time interval is calculated.In the time interval measurement method of this paper,the time interpolation signal is the envelope signal output by the band pass filter,and the specific implementation of the band pass filter uses the SAW filter based SAW technology,which can narrow the pulse.The signal is converted to an envelope signal of a certain width,which in turn converts a single measurement into multiple measurements.In the process of correlation,a data search algorithm based on binary search is added.The experimental test shows that the calculation amount can be reduced by at least 90%,which greatly improves the response speed of the time interval measurement.Due to the average effect of the correlation function operation,the additional noise components in the two uncorrelated signals can be effectively removed,and the noise floor of the measurement system is reduced,thereby reducing the measurement error of the measurement system.The measurement system can be divided into four sub-modules according to the function,including signal pre-processing,band-pass filtering,sampling and storage,and data processing,in which the data processing is the software part and the rest is the hardware part.The measurement system can measure the two input signals.In the measurement process,the pre-processing,band-pass filtering and sampling of the input signal are divided into two paths,and then the two sampling data are stored and transmitted through the FPGA.The simulation and specific experiments of the measurement system show that the measurement system has a measurement accuracy of 0.87 ps rms at a sampling rate of 105 MHz and an input signal of 1 MHz.