Navigation System In The Phase Noise Model Establishment And Analysis

Frequency drift and frequency offset exist not only in the atomic clock, whichusually as the source of time and frequency signals, but also in the oscillator of receivertracking loop. And they usually affect the precision of ranging and velocitymeasurement. Especially in high-precision navigation system, we should consider theimpact of phase noise on the satellite ranging and velocity measurement.As precision navigation electronic equipment, the output signals of frequencysource not only are influenced easily by all kinds of other inner electronic noise, butalso are influenced easily by external environmental changes, making output frequencyinconstant. So phase noise is generally the random fluctuation of output signals causedby various inner system noises, it mainly affects short-term frequency stability offrequency source. Thus carry out the research of phase noise in navigation system willmake grate sense.This dissertation focuses on phase noise’s concept, representation in time andfrequency domain, and describes the expression of phase noise with power law model.On this base, main research is on how to generate phase noise and this dissertation givesthe simulation results, providing theory basis and realization methods for study ofstandard frequency source’s short-term frequency stability.Firstly, this dissertation introduces standard frequency source’s output signalsfrequency spectrum both ideally and interfered by phase noise, physical meaning ofshort-term frequency stability, phase noise representation in time and frequency domainand gives the relation between these two expressions and transformation method.Then, based on the power law noise produced by three classical statistic modelsmethod, this dissertation extends to generate other four kinds of power law noise, andfinally add them together in accordance with their individual weight coefficient togenerate phase noise. These three methods are based on wavelet model method, ARMAand fractional order integral method (IIR). Three methods for generating power lawnoise are described and deduced by formulation in detail, and each power law noise’s results of time domain sequence, power spectrum estimation in frequency domain andAllan variance by Matlab are given. And compare the frequency-domain simulationresults of each power law spectral component with the ideal curve. At the same time,use Matlab to simulate the phase noise which is added five power law noises accordingto their weighting coefficients.At last, the correctness and feasibility of three methods are verified according todiscrete sampling points at the phase noise of oscillator’s real output. On this basis, thedissertation analyzes and simulates the impact of phase noise on the carrier trackingaccuracy. After that, comparison of these three methods and conclusion are given.