| With the rapid development of wireless communication technology,the transmission method and transmission range of information have been changed greatly,which makes it a reality for the whole world to be connected easily.In fact,different application scenario of wireless communication determines that various communication standards,frequency range and modulation schemes will be needed.Though it enjoys great popularity,the fourth generation mobile communication technology is moving forward to the fifth generation mobile communication technology,which accelerates the speed of information transfer.Meanwhile,it is likely to be accompanied by the incompatibility between the new protocol standards and the original hardware devices.By then,the existing equipment will not be able to meet the satisfaction of the new standards.Moreover,to replace the incompatible equipment will cost a large amount of money.As one of multi-port application,the multi-port receiver can receive and demodulate the signal which is different in frequency,communication protocol and modulation methods by adjusting the software parameters without changing the hardware device.And multi-port reflectometer,which is simple and compatible with different standards,can achieve accurate measurements of wide band data.Once hardware and signal errors occur,the accuracy of demodulation and the speed of multi-port will be affected.Out of necessity,deeper significance should be attached to the research on the calibration techniques of multi-port and its application.Above all,it analyzes the principle and structure of multi-port microwave network as well as the circuit component and microwave parameter.And on this basis,the classification,component and demodulation process of six-port and five-port direct conversion receiver are discussed.By studying the sources of error and calibration standards,the error models and calibration method of multi-port microwave network are also proposed.Besides,on the basis of the analysis of main parameters of multi-port microwave network,the calibration method for multi-port microwave network is put forward.By analyzing microwave theory and calculating,the calibration equation of multi-port reflectometers got and calibration method for the error items by the least square method with weight factor is proposed.At the same time,mismatch error for load is calibrated by using error box and the result shows that the performance in magnitude and phase is good while the reflectometer is calibrated by this method.Last but not least,the calibration technique of multi-port direct conversion receiver is discussed.By means of studying the error items of the receiver,this thesis presents a novel calibration algorithm in software based on real-valued delay-time and genetic algorithm’s neural network.It is desirable that the accuracy of demodulation can be improved without changing the hardware and overall imperfections in the receiver are calibrated using this calibration algorithm.What’s more,the results show that the receiver calibration method can help with a higher precision and smaller error vector magnitude(EVM)when it demodulates different signals. |
