## 6 Conclusions  
In this paper, the theoretical model of phase noise and its simulation methods in frequency and time domains are firstly studied, and the power law spectrum model in the frequency domain and a typical method for solving phase noise jitter in the time domain are given. Then, for typical communication measurement systems, the two problems of phase-noise frequency-domain transfer and time-domain noise generation are studied, respectively. The frequency domain transfer function of phase noise in a carrier tracking loop is given, and the different effects of thermal noise and phase noise on the output of common third-order phase-locked loops are analyzed. A time-domain phase noise sequence generation algorithm based on discrete fractional integral operation is proposed. For the measured single-sideband phase noise spectrum of an OCXO, the proposed algorithm is used to generate the various order components of the power law spectral model and the integrated time-domain noise sequence, and the simulated SSB phase noise is generated by calculating again from this sequence. The result is in good agreement with the measured result of the instrument, which shows the effectiveness and accuracy of the algorithm. Finally, a communication measurement simulation system is built, and a discrete sequence simulation analysis method combining the frequency domain and time domain is provided, and the coupling relationship of key indicators such as phase noise, thermal noise, communication data rate, modulation method and bit error rate is synthesized. The results show that the bit error rate of the QPSK/BPSK communication system will not be significantly reduced if the phase jitter RMS caused by phase noise is less than 5 degrees, so 5 degrees can be used as a reference for the decomposition of the carrier SSB phase noise index. In addition, for modulation modes of 8 PSK and higher order, the effect of phase noise is more significant, and the Eb/No index of the channel containing the phase noise is significantly increased compared with the case of the Gaussian white noise channel. The simulation gives some analysis results under the common technical indicators of the satellite inter-satellite link system, which provides an effective reference for the engineering design of a certain type of payload.  
Conceptualization, X.L., H.L. and X.W.; Methodology, X.L., Y.H., F.W. and X.W.; Software, H.L. and F.W.; Validation, X.L., Y.H. and F.W.; Formal analysis, H.L., Y.H., F.W. and C.Z.; Investigation, X.L., H.L., Y.H., F.W., C.Z. and X.W.; Resources, Y.H., C.Z. and X.W.; Data curation, X.L., H.L., Y.H., F.W. and C.Z.; Writing--original draft, X.L.; Writing--review & editing, C.Z. and X.W.; Visualization, C.Z. and X.W.; Supervision, H.L. and Y.H.; Project administration, X.W.; Funding acquisition, X.W. All authors have read and agreed to the published version of the manuscript.  
Figure 16: Bit error rate curve under different modulation methods when phase noise RMS = 5\({}^{\circ}\).  
**Funding:** This research was funding by China Aerospace Innovation Fund (21 GFH-HT01-336).  
**Data Availability Statement:** (1) The phase noise test data used to support the findings of this study are included within the article, listed below: (a) Typical Ka signal phase noise test results as Figure 3 and Table 1, which can be read out directly; (b) Power law spectrum parameters of a typical oscillator which is used to support the tracking error of PLL in Section 3 are included in Table 3; (c) Phase noise measurement of 5 MHz OCXO in Figure 8 is used to support Figures 9-11. All relevant data can be found in Section 4. (2) The simulation data used to support the findings of Section 5 are available from Matlab/Simulink.  
**Conflicts of Interest:** The authors declare no conflict of interest.