Research On Phase Noise Measurement Technology

Phase noise is an important index to measure signal fluctuation in the time and frequency domain.With technological innovations in the optoelectronic communication,satellite navigation and electronic countermeasures fileds,how to achieve wide-range,high-resolution phase noise measurement becomes a key problem.The relationship between phase difference and phase noise of periodic signals is clarified by studying the representation of phase noise.The theory and limitations of phase comparison technology and phase noise measurement technology are analyzed by researching the traditional phase noise measurement theory.On these basis,a high-precision single-sideband phase noise measurement scheme based on digital linear phase comparison method is determined.By discussing the special application of quantization theory in phase comparison,a phase-continuous,high-resolution digital linear phase comparison method based on the least common multiple period is proposed to achieve high-precision phase difference.The method utilizes a high-speed analog-to-digital converter as a counter and an equivalent phase detector to achieve direct phase comparison between arbitrary signals on the basis of the least common multiple period.Due to its fully digitalized mode and direct phase comparison characteristics,the digital linear phase comparison method has the advantages of low ground noise,simple measurement and easy implementation.Using the high-stability crystal oscillator 8607 for self-calibration phase comparison experiments,it is found that the frequency stability of phase processing has a 1/?law,and the second-order frequency stability can reach1.68?10^{-1 2}/s,which verifies the digital linear phase comparison method's high precision in the phase comparison between signals with different frequency.By analyzing the deviation and variance performance of the autocorrelation method,the power spectrum estimation error is effectively reduced by adopting the method of truncating the auto-covariance sequence,increasing the sample length and averaging multiple measurements.By studying the correspondence between the signal in the time domain and the frequency domain,it is found that the partial carrier frequency has a one-to-one correspondence with the phase-to-phase time.For the phase noise at the far carrier frequency,too little sample data will cause the stepped frequency value to be too large to reflect the power distribution of the signal;for the phase noise at the near carrier frequency,the phase comparison time is longer,and too much sample data will result in a system response time that is too long,too little sample data will result in large measurement errors.In addition,the phase noise of a single measurement has a large random error,but the response time of the system will be too long if the number of measurements is increased.Considering various factors,the length of samples,phase comparison time and average number of measurements in different partial carrier frequencies were determined by multiple comparison experiments.A high-resolution phase noise measurement scheme was designed and implemented.Using the scheme and PN8010phase noise measuring instruments to measure the phase noise of the TR2001 Rubidium clock and OSA 5585B PRS Cesium clock respectively,the relative error of the phase noise measurement scheme is determined by comparing the difference between the phase noise measurement results.