Design And Implementation Of EVM Algorithm In GMR-1 3G Terminal Test Set

The research and development of the integrated platform for GMR-1 3G satellite terminal RF conformance testing can fill the gap of the satellite industry,and it is the development direction of satellite communication.Error Vector Magnitude(EVM),which represents the quality of the signal modulation,is a significant index of the non-power class in the RF conformance test of the transmitter.Due to the frequency offset estimation is completed based on the timing synchronization,which are extremely dependent on the style of modulation,but also introduces the I/Q imbalance parameters estimation and correction into the solution of reference signal imprecise construction,so the EVM algorithm in satellite terminal test set is studied from the following two aspects in this thesis.A method to construct the new sequence by differential conjugation is introduced in the synchronization algorithm based on pilot frequency sequences to be the symbol synchronization algorithm.And it is combined with the existing method of minimum modulus variance,which is the sample point synchronization algorithm,to be the improved synchronization algorithm.The simulation results show that the improved synchronization algorithm can guarantee the synchronization error less than 10 samples and completes the precise synchronization of the signal with the theoretical frequency offset in the range of 1500 Hz.In order to solve the problem that the estimation accuracy of FFT based on pilot frequency sequences and FFT-CZT is not ideal,a full burst multi-point FFT algorithm is proposed.To solve the problem that time complexity of the above three algorithms,the frequency offset estimation algorithm taking advantage of unique word in time domain is designed.The simulation results of four frequency offset estimation algorithms show that the algorithm using unique word in time domain has the optimal performance that high accuracy and low time complexity.The conventional structure method of reference signal is combined with the estimation of I/Q unbalance parameters to be optimized reference signal structure.The simulation results show that the reference signal constructed by optimized method coincides with the ideal modulation signal under the common engineering condition that signal to noise ratio 30 dB.Aiming at the accuracy optimization problem of applying binary linear fitting method,application of particle swarm optimization and generalized inverse matrix method in the I/Q imbalance estimation algorithm are proposed.The simulation results show that accuracy of the proposed algorithms is optimized,but the time complexity of applying the particle swarm optimization is about 10 times that of the other two algorithms.The I/Q unbalanced parameter estimation algorithm using generalized inverse matrix realizes the goal of improving the accuracy of estimation under the premise of guaranteeing efficiency.Finally,the overall function of the EVM algorithm is verified by simulation.The simulation results show that the EVM algorithm proposed in this thesis can achieve the measurement function.The accuracy of the EVM algorithm is verified by the instruments,and the test results show that the accuracy of the algorithm is enough to be used for measurement.In summary,the accuracy of EVM algorithm rised in this thesis meets the requirements of GMR-1 3G,and it is reasonable and feasible in engineering realization.