Research And Implementation Of Measurement Items In GMR-13G Terminal Test Set

The research of GMR-1 3G satellite terminal RF conformance testing can fill the gap of the industry and contribute a lot to the development of satellite communication.The measurement item is the core module of testing system and plays a key role in RF conformance testing.Because the transmission distance of satellite communication system is long and the Dopper effect is obvious,the accuracy of terminal signal transmission time,carrier frequency and power control is the key.The thesis focuses on design and implementation of measurement items including On/off power VS time,time-frequency error and closed-loop power control.And the main research contents are timing synchronization,frequency offset estimation and implementation method for each measurement item.Firstly,the thesis researches the common synchronization algorithm,including symbol synchronization that is named sliding correlation method and sample synchronization that is named minimum amplitude variance method.Since the data has been under-used and AWGN is not considered,the synchronization accuracy of minimum amplitude variance method is low.In order to improve the accuracy,a new algorithm is proposed that is based on the principle of smoothing AWGN with mass data and power symmetry.It is combined with the sliding correlation method to be the improved synchronization algorithm.The simulation results show that the improved synchronization algorithm has higher synchronization accuracy and better anti-noise property.Then,the maximum likelihood estimation algorithm of frequency offset is introduced.Considering the difficulty of implementation,this thesis studies the more practical classical algorithms for frequency offset estimation that are based on the maximum likelihood theory.For GMR-1 3G satellite communication system,the capture range of classical algorithms was halved due to modulation method.And the classical algorithms are difficult to satisfy both capture range and estimation accuracy.Aiming at these problems,a new method based on phase characteristics is proposed.The simulation results show that the new method doubles capture range of classical algorithms and has better performance in accuracy.Finally,according to measurement protocol,the requirements and key points of each measurement item are studied.And the test flows are designed in detail.Then the comparison between measurement items and spectrometer shows that the design of this thesis is correct.