Research And Implement Of Baseband Vector Signal Software Simulation Technology

With the rapid development of modern communication systems and the emergence ofnew communication equipments, there are high requirements for test methods and testinstruments in accuracy, test parameters, test speed, frequency range and other aspects. Thevector signal generator as one of important test and measurement instruments also developsrapidly. The method of the baseband signal generation has developed into a softwareimplementation. Vector signal source simulation software can not only shorten thedevelopment cycle, reduce costs, but also own high stability, ease of use and scalability.In this thesis, in order to achieve the design goal of using software to produce a basebandsignal, using Visual C++6.0development platform combined with Microsoft SQL2008, thegeneration of baseband vector signal is fulfilled, and constitute vector signal generator bysending the data to hardware platform, in addition, the software also has the function of signalwaveform analysis, saving the parameters set by users, queriing the history data. The mainresearch and innovation are as follows:1. Based on the research of vector signal generator’s theory, the architecture, logicarchitecture, physical architecture, overall framework of vector signal generator are designed,and this framework owning high scalability and high ease of use are proposed.2. The theory of baseband signal quadrature modulation is studied, and a new method offufilling the quadrature modulation of FSK is propsed. This software fulfill more than twentykinds of modulation, including ASK、PSK、FSK、QAM. The achievement of the quadraturemodulation of FSK is not only difficult but also innovative. Usually, the method of FSKimplementation is DDS (direct digital frequency synthesis), but signal generated by thismethod is not consisteny with other kinds of modulation in this software. The method of FSKwhich is put forward in this thesis not only overcomes the difficulty, but also produces imagesuppression, improves the transmission rate, effectively reduces the interference.3. I, Q imbalance is artificially added in the module of code source mapping module totest the anti-systematic errors performance of the receiving device, in order to realize the errorsignal bit easier insertion.4. In this software, signal graphical analysis function is designed. Users can visuallyobserve a baseband signal through analysis and query historical data of the constellation, vector diagram, time domain diagram, spectrum. The function of queriing historical data isfulfilled by Visual C++6.0combined with Microsoft SQL2008database.It has been proved that using the software to generate baseband signal not only shortensdevelopment cycles, accelerates the progress of research and development, greatly reduces thecost, saves manpower, but also has a high value in engineering.