Design And Research On The TED Algorithm Insensitive To Carrier Frequency Error

An algorithm used in TED (Timing Error Detector) module in digital communication receiver which has the ability to confront carrier frequency offset is proposed. It is an improvement of the widely employed Gardner algorithm, and it resolved the problem of Gardner algorithm's susceptibility to carrier frequency offset. This paper discovered independently the cyclic feature of impact on Gardner algorithm's performance by increase of carrier frequency offset, and designed independently a resolution to combat the impact by utilizing this feature. Simulation results show, under the conditions described in this paper, the algorithm proposed by this paper possesses better anti-carrier-frequency-offset ability. Comparing with Gardner algorithm, the algorithm proposed by this paper cuts down the performance deterioration caused by carrier frequency offset by between 25% and 89%.This paper used the simulation tool of Matlab7.0, constructed the model of the whole timing recovery loop comprising the TED module and modules cooperating with it, and run the model with modules other than TED module set to the ideal state and introducing no error, thus isolated and researched the performance of the TED module. Through tentative and repetitive theoretical deduction and simulative verification, the proposed algorithm resulted. Moreover, this paper analyzed, simulated and compared the performance of Gardner algorithm, Lou algorithm, Lim algorithm and the algorithm proposed by this paper. This paper summarized a number of papers researching Gardner algorithm, and proposed independently the theory that the perspectives regarding Gardner algorithm self-noise can be classified into three categories, and the rationality of this classification is demonstrated. This paper represents the procedure in which the algorithm is deduced. Because the algorithm proposed by this paper necessitates the accurate calculation of the Gardner algorithm S-curve slop, this paper represented one accurate way to calculate the referred slop. And the result of the calculation is different with other papers in the procedure and the result because of the presumption used in this calculation is unique and proper only to the algorithm proposed by this paper. The simulation result verified the legitimacy of this way of calculation. And this paper calculated the MCRB of Gardner algorithm and the algorithm proposed by this paper independently. The contribution of this paper rests in the proposition of a way to estimate and correct the carrier frequency offset within TED module, which provides a candidate resolution for the design of TED module, and provides a reference for the design of receivers in combating carrier frequency offset. The classification of perspectives regarding Gardner algorithm's self-noise and the way of calculating Gardner algorithm's S-curve slope and MCRB proposed by this paper provide new theory and are valuable as reference for new design and improvement based on Gardner algorithm.