Abstract
In this thesis, the theory and measurement methods of phase noise, including measurements in frequency domain and time domain, were discussed. Phase noise in signal spectrum is usually measured by using spectrum analyzer. However, the spectrum analyzer can not measure the phase noise in time domain. In this thesis, a coherent demodulation technique is utilized for measuring the phase noise in time domain. A new frequency estimation method is proposed to compensate the measurement error due to the frequency deviation between the demodulation signal and carrier signal. A DSP-based phase noise measurement system was developed to implement the aforementioned phase noise measurement in both time domain and frequency domain. It employs a high-speed A/D converter to acquire the signal under test. The Fast Fourier Transform was utilized to compute the signal spectrum and analyze the phase noise component of the signal in frequency domain. Meanwhile, the digital demodulation technique proposed above is used to obtain the phase noise waveform. The system can operate in stand alone mode via the EEPROM, or be controlled by a PC via ISA Bus. The control program on the PC side was also written to help users observe the phase noise measurement results. Some field measurements were performed and the results were comparable with those of HP8560E and 8595A spectrum analyzers.