The Design And Implementation Of Key Test Cases For Satellite Terminal RF Conformance Test

Terminal RF conformance test instrument can be used in terminal research and development testing,terminal finalization,production testing and other stages.The development of satellite terminal RF conformance test instrument can help promote the development of satellite communications in China.Some key test cases including Error Vector Magnitude(EVM)and Bit Error Rate(BER)test cases in the RF conformance test instruments for satellite terminals are designed and implemented in this thesis.Finally,the feasibility of the design scheme is verified by experimental results of the scheme.The EVM test scheme is divided into three modules: timing synchronization,carrier synchronization,and I/Q imbalance parameter estimation.After completing the algorithm design of the above three modules,the EVM test results can be obtained.In the design of the timing synchronization algorithm,combining the characteristics of the signal to be measured,the method of "symbol level synchronization first and then optimum sampling point synchronization" is proposed.In symbol level synchronization,the strong correlation of the pilot data is used to find the maximum correlation value point of the received signal and the local pilot data in the sliding window to complete the symbol level synchronization.In the optimal sampling point synchronization,in order to solve the problem of poor anti-noise ability of the traditional algorithm,a half-symbol power difference minimum method is proposed.This method reduces noise effects by accumulating multi-channel data,and then finds the best sampling point based on the left and right symbol power symmetry characteristics.The simulation results show that the new algorithm has higher synchronization accuracy and stability,and stronger anti-noise ability.In the design of the carrier synchronization algorithm,a new union carrier frequency offset and phase offset estimation algorithm is proposed.The signal modulation information first is removed with the method of cumulative decision differential modulation phase,and then jointly estimates carrier frequency offset and phase offset based on the idea of generalized inverse matrix.The simulation results show that although the new algorithm sacrifices the normalized frequency offset estimation range of 0.02,the lower normalized frequency offset mean square error,the lower signal-to-noise threshold and higher phase offset estimation accuracy are achieved for this algorithm.In the design of the I/Q imbalance parameter estimation algorithm,the parameter estimation problem is transformed into an optimization problem based on zero-IF transmitter I/Q imbalance model.In view of the shortcomings in the optimization process of the particle swarm optimization algorithm,an escape mean simplified particle swarm optimization algorithm is proposed.On the basis of simplified particle swarm optimization,the mean search strategy and escape strategy are added to enhance the global optimization ability of the algorithm.The simulation results show that the new algorithm has higher accuracy in parameter estimation.In the design of BER test scheme,a non-loopback BER test scheme is proposed for the BER test of the asymmetric channel.In this scheme,the data is transmitted through the outer loop link.In addition,synchronization mechanism,outer loop reliability assurance mechanism and exception handling mechanism are added to ensure that the test can be carried out accurately and stably.Finally,according to the design scheme of this thesis,the EVM and BER test cases are implemented.In EVM experimental verification,the error between the terminal tester and the spectrum analyzer EVM test is less than 0.1%,and the test results are accurate,which verifies the feasibility of the EVM design scheme.In the BER experimental verification,the BER test results are accurate under normal and abnormal conditions.The feasibility of the BER design scheme is verified.