Phase Noise Of Automatic Test Methods Research

In the modem technology of wireless and radar communication, low-noise signal source is very important for improving system performance. The source phase noise is one of the most important limiting factors. In this paper, different methods to describe phase noise, both in time domain and frequency domain, are introduced. In the frequency domain, there are three common ways to measure phase noise: direct spectrum analyzer method, frequency detector method and quadrature method. Due to the high testing precision and wide testing frequency range, the quadrature method is widely used. The HP3047A phase noise measurement system is a typical instrument utilizing this method to test phase noise. The paper analyzes the algorithm and testing measure of 3047 and transplants the system control software to Windows platform. The system performance is highly improved. The system is transformed from a simple Automatic Measurement System to a Virtual Instrument with opening, blocking, reusable and interchange characters. The new system can measure a source in multi-frequency point automatically. The testing precision has reached the design requirement.