The composite time scale(CTS)provides a stable,accurate,and reliable time scale for modern society.The improvement of CTS’s real-time performance will improve its stability,which strengths related applications’perfo...The composite time scale(CTS)provides a stable,accurate,and reliable time scale for modern society.The improvement of CTS’s real-time performance will improve its stability,which strengths related applications’performance.Aiming at this goal,a method achieved by determining the optimal calculation interval and accelerating adjustment stage is proposed in this paper.The determinants of the CTS’s calculation interval(characteristics of the clock ensemble,the measurement noise,the time and frequency synchronization system’s noise and the auxiliary output generator noise floor)are studied and the optimal calculation interval is obtained.We also investigate the effect of ensemble algorithm’s initial parameters on the CTS’s adjustment stage.A strategy to get the reasonable initial parameters of ensemble algorithm is designed.The results show that the adjustment stage can be finished rapidly or even can be shorten to zero with reasonable initial parameters.On this basis,we experimentally generate a distributed CTS with a calculation interval of 500 s and its stability outperforms those of the member clocks when the averaging time is longer than1700 s.The experimental result proves that the CTS’s real-time performance is significantly improved.展开更多
Introduction Detecting a pulse correctly is a key process in nuclear detection.Because the radiation emission is a random process,it is hard to design a suitable peak-detection approach in FPGA.The error detection wil...Introduction Detecting a pulse correctly is a key process in nuclear detection.Because the radiation emission is a random process,it is hard to design a suitable peak-detection approach in FPGA.The error detection will influence the final energy spectrum and flood histogram.In order to improve the result of nuclear detection,this paper proposes a novel method for nuclear signal peak-detection,which can improve both the effective counting rate and the quality of pulses in real-time.Methods The main method is to establish a normalized reference pulse regardless of waveform through the least squares method.By calculating the loss between the incoming data stream and normalized reference pulse,this algorithm retains the pulses whose loss is below the threshold.We select the threshold based on statistical methods.The algorithm is implemented on field programmable gate array(FPGA)successfully,and this process is able to work in real-time.Conclusion The result shows that the effective counting rate can improve about 19.8%and more than 99%pile-up and error pulses will be suppressed.By analyzing reserved pulses,the energy spectrum and flood histogram could be well rectified.The energy resolution increases 11%compared with traditional algorithm.Furthermore,due to this new algorithm,the low-energy threshold can be lower.展开更多
基金the National Key Research and Development Program of China(Grant No.2021YFA1402102)the National Natural Science Foundation of China(Grant No.62171249)the Fund by Tsinghua University Initiative Scientific Research Program.
文摘The composite time scale(CTS)provides a stable,accurate,and reliable time scale for modern society.The improvement of CTS’s real-time performance will improve its stability,which strengths related applications’performance.Aiming at this goal,a method achieved by determining the optimal calculation interval and accelerating adjustment stage is proposed in this paper.The determinants of the CTS’s calculation interval(characteristics of the clock ensemble,the measurement noise,the time and frequency synchronization system’s noise and the auxiliary output generator noise floor)are studied and the optimal calculation interval is obtained.We also investigate the effect of ensemble algorithm’s initial parameters on the CTS’s adjustment stage.A strategy to get the reasonable initial parameters of ensemble algorithm is designed.The results show that the adjustment stage can be finished rapidly or even can be shorten to zero with reasonable initial parameters.On this basis,we experimentally generate a distributed CTS with a calculation interval of 500 s and its stability outperforms those of the member clocks when the averaging time is longer than1700 s.The experimental result proves that the CTS’s real-time performance is significantly improved.
基金This work is supported by the Instrument Developing Project of the Chinese Academy of Sciences Grant 29201707。
文摘Introduction Detecting a pulse correctly is a key process in nuclear detection.Because the radiation emission is a random process,it is hard to design a suitable peak-detection approach in FPGA.The error detection will influence the final energy spectrum and flood histogram.In order to improve the result of nuclear detection,this paper proposes a novel method for nuclear signal peak-detection,which can improve both the effective counting rate and the quality of pulses in real-time.Methods The main method is to establish a normalized reference pulse regardless of waveform through the least squares method.By calculating the loss between the incoming data stream and normalized reference pulse,this algorithm retains the pulses whose loss is below the threshold.We select the threshold based on statistical methods.The algorithm is implemented on field programmable gate array(FPGA)successfully,and this process is able to work in real-time.Conclusion The result shows that the effective counting rate can improve about 19.8%and more than 99%pile-up and error pulses will be suppressed.By analyzing reserved pulses,the energy spectrum and flood histogram could be well rectified.The energy resolution increases 11%compared with traditional algorithm.Furthermore,due to this new algorithm,the low-energy threshold can be lower.
