Design And Implementation Of APSK32 Signal Demodulation

This thesis is based on the application development task of “Research on Digital Modulation Signal Test and Analysis in Hybrid/Heterogeneous Network”,which belongs to the project of the national key scientific instrument and equipment development program “Research and Application Development on High Performance Spectrum Analyzer”(No.2012YQ20022404).The vector signal analysis products with independent intellectual property rights need to be researched and developed and the relative studies on the techniques are with great significance and practical value since the products depend on massive import,which impose a fiscal pressure upon our nation.The Vector Signal Test Analyzer achieves a series of digital modulations.It demodulates measurement signals,and measurement results,IQ diagrams,spectrums,constellations,error parameters and other performance indicators are displayed.APSK32 signals demodulation framework and calculation the indicators of measurement are designed and implemented.The main ideas in the thesis as follows:Firstly,introducing the system framework of the Vector Signal Test Analyzer and depicting an outline about the key techniques in APSK32 signal demodulation.Specifically,according to the theories and required functions of the Vector Signal Test Analyzer,states the main problems to be solved in APSK32 signal demodulation,and lay the foundation for the relevant design and development.Secondly,designing and implementing the scheme of APSK32 synchronization.Considering the practical applications,the Vector Signal Test Analyzer is required to fastly demodulated the received signals so that the output of the measurement results can keep in pace with the signal generator.Thus,Gardner timing synchronization algorithm is adopted to achieve the demodulation of APSK32 signals.The Vector Signal Test Analyzer need to estimate and compensate the carrier frequency offset of the received signal with unknown frequency offset range.Accurate frequency offset estimation value can be obtained with this algorithm when the symbol length is short.Therefore,an M&M+Fitz joint frequency offset estimation algorithm is designed,which captures a wide range of frequency offset with precise value.At the same time,the M-power + V&V algorithm is designed and implemented to estimated and compensation the phase-offset to reduce the complexity in engineering implementation.The decision is made by de-mapping the amplitude and phase.Finally,developing and implementing the APSK32 demodulation framework.Given the software performance and the time complexity of the algorithm,the APSK32 signal demodulation framework is developed,and the outputs are compared with those of Agilent 89600 VSA software in the same condition.It shows that the APSK32 demodulation framework designed and implemented in this thesis meets the requirements of the project indicators,and the performance is closed to the Agilent 89600 VSA software.