Vector Signal Analysis Software Design

In modern radio communication network system, digital transmission has become a widely used communication mode with its advantages in the spectrum efficiency and anti-interference.Consequently, demand for digital modulated signal analysis is becoming increasingly urgent. Among them, vector signal analysis technique have become the main method which used for the analysis of digital modulated signal. The vector signal analysis technology is an important direction of the Measuring and Testing Technology. At present, most of the vector signal analysis based on the idea of software radio, to deal with the vector signal using software has become a broader trend. Therefore, digital signal processing algorithms and the corresponding software are more and more important in the vector signal analysis.This paper aim at the demand and development trend above, taking modulation quality analysis software design on modulated signal such as ASK、FSK、QPSK as the research object. On the basis of in-depth analysis on the theory and technology of the vector signal, a new solution base on software radio on vector signal analysis has proposed. This solution is based on Digital Quadrature Demodulation method, carrier frequency offset and phase joint estimation algorithm in open-loop and timing phase estimation algorithm in open-loop to achieve the demodulation. Thus, to complete the digital modulation signal demodulation and judgment, finally get demodulation bit stream. Then, according to the theory of error vector, calculating the reference signal via demodulation result, comparing it with two I/Q signal, and finally obtaining the error vector magnitude(EVM), and the statistical results of parameters, such as amplitude errors and phase errors, as well as the constellation diagram that describe the quality of digital modulation signal.According to the above theory and algorithm researching, combining with the design method of automatic test system(ATS), using programmable instruments or DAQ(data acquisition boards) as the front-end data acquisition device with the personal computer to construct the hardware platform for automatic test system. Using Labwindows/CVI for the vector signal analysis software design and implementation, finally, formed into automatic test system. In the process of software design, following the standard software development process, through the demand analysis, software architecture design, module design, data processing and algorithm design and the system debugging, completed the establishment of software development and testing system.