基于Kay加权的高动态载波跟踪环路初始频差估计方法

Initial Frequency Offset Estimation Method for High Dynamic Carrier Tracking Loop Based on Kay Weighting

在高动态环境下,过大的载波跟踪环路初始频差会导致环路失锁或误锁。针对该情况已有学者通过增强环路跟踪稳定性和鉴频能力来解决,但仍存在鉴频范围小,精度低和运算量大等问题。为解决上述问题,提出了一种基于Kay加权的载波跟踪环路初始频差估计方法,该算法首先对跟踪环路中I、Q两路的短时积分结果进行二倍角处理,然后,再对其使用四象限反正切鉴频器鉴频,最后借鉴Kay算法对鉴频结果加权得到频差估计值。通过与传统方法做计算机仿真对比,结果表明:在信噪比为-26 dB及以上时,在相同运算采样点数的前提下,本文方法估计精度相较于最大似然估计和三阶锁频辅助四阶锁相环路方法分别提升8.72 dB和19.59 dB或更高。在达到相同估计精度情况下,本文算法运算采样点数为最大似然估计方法的6.25%,算法运算量中加法与乘法次数仅为其1.7%和5.6%,计算时长为其1.56%。

In the high dynamic environment,the initial frequency difference of carrier tracking loop is too large,which will lead to loop lock loss or false lock.Some scholars have solved this problem by enhancing the stability of loop tracking and the capability of frequency discrimination,but there are still some problems such as small range of frequency discrimination,low accuracy and large amount of computation.To solve the above problems,an initial frequency offset estimation method was proposed for carrier tracking loop based on Kay weighting.Firstly,the short-time integration results of I、Q two channels in the tracking loop were processed by double angle,and then,the frequency offset estimation was obtained by using four-quadrant arctangent frequency discriminator.Compared with the traditional method by computer simulation,the results show that the estimation accuracy of the proposed method is 8.72 dB and 19.59 dB higher than that of the maximum likelihood estimation and the third-order frequency-locked aided fourth-order phase-locked loop method respectively under the premise of the same number of operation sampling points when the signal-to-noise ratio is-26 dB or above.Under the condition of the same estimation accuracy,the number of sampling points of the proposed method is 6.25%of that of the maximum likelihood estimation method,the number of addition and multiplication in computation of algorithm is only 1.7%and 5.6%,and the calculation time is 1.56%.