因此，解调前必须去除频率偏差。
OFDM的主要缺点是对载波频率偏差很敏感。
One of the principal disadvantage of OFDM is sensitivity to frequency offset.
为计算频率偏差，提出了一种新的频率计算方法。
For calculating the frequency variance, a new method was proposed to calculate the ridge frequency.
然而，OFDM系统对频率偏差和相位噪声比较敏感。
However, OFDM is sensitive to frequency offset and phase noise.
该算法具有较大的估计载波频率偏差的范围和较高的估计精度。
The algorithm features the large estimation range for carrier frequency deviation and high estimation accuracy.
结合AGC分级控制的特点，按频率偏差等级设定频率偏差系数。
Based on the character of AGC hierarchical control, it presents different bias Settings according to diverging frequency grade.
此参数指定一个最高和最低频率偏差，以百分比表示或百万分之的。
This parameter is specified with a maximum and minimum frequency deviation, expressed in percent or parts per million.
针对电网出现的频率偏差，提出一种谐波负序电流指令的检测方法。
According to the frequency excursion in power systems, this paper proposes a detecting method of harmonic negative current instructions.
但是OFDM技术有众所周知的缺点：对定时偏差和频率偏差十分敏感。
However, there are well-known shortcomings of OFDM technology: the timing offset and frequency offset is very sensitive.
设计了一种基于环形CCO的锁相环自动频率调谐结构来减小频率偏差。
Furthermore, a ring CCO based frequency tuning scheme is proposed to reduce frequency variation.
但是实际需要的是使频率偏差的绝对值最小而不是频率偏差的平方和最小。
However we want to get the least absolute value of frequency deviation not the least square sum of it.
但是与此同时，OFDM技术自身存在着两个主要的缺点：对频率偏差敏感；
While in the meantime, OFDM has its own shortcomings: its sensitivity to a frequency offset and the high peak-to-average ratio.
提出了一种改进的桨距角控制方案——将系统频率偏差信号引入桨距角控制系统。
An improved pitch control scheme is presented by introducing a frequency deviation signal into the control system.
在理想同步采样的条件下，提出了一种基于简谐信号复幅度的频率偏差求取算法。
Based on the complex magnitude of harmonic signals and under the condition of ideal synchronous samplings, an algorithm for computing the frequency deviation is proposed.
这种算法具有所需数据窗的时间短、计算精度高和不受系统频率偏差影响的优点。
This algorithm needs shorter data window time and has higher calculation precision and is not affected by deviation of power frequency.
如何实现极窄的通带宽度和极小的中心频率偏差是研制中所解决的关键技术问题。
The key technique of this new filter is how to achieve the extreme narrow band-pass width and a slight deviation of central frequency.
为此，在频率控制领域首次引入了最佳逼近算法，它能给出频率偏差的最小-最大解。
Pell equation and its solution are introduced and also some theorems about minimum solutions of Pell equation are given out.
在分析国外研究状况及中国AGC实际运行的基础上提出了一种频率偏差系数确定方法。
A frequency bias coefficient setting technique is proposed by analyzing the investigative status abroad and AGC performance in China.
OFDM系统自身的正交多载波调制特点，决定了其对定时误差和载波频率偏差十分敏感。
The orthogonal multicarrier modulation, which is the main character of OFDM, determines that it is very sensitive to both timing synchronization error and carrier frequency offset.
而产生ISI和ICI的主要原因是在OFDM系统接收端产生的符号定时偏差和载波频率偏差。
The most critical causes yielding the ISI as well as ICI are symbol timing and carrier frequency offset which are occurred in the OFDM receiver.
详细描述了军用电力系统的频率偏差，频率测试特点及测试平台设计，讨论分析了实际测试结果。
The paper describes frequency bias, characteristic of frequency measurement and test platform design. Measurement results are discussed.
为了减小正交频分复用系统受频率偏差的影响，在OFDM系统中设计了一种新的载波频偏估计算法。
To reduce the impact of carrier frequency offset in OFDM system, this thesis designs a new carrier frequency offset estimation scheme for OFDM system.
在无线移动通信中，接收机的本地振荡频率和载波频率之间往往存在较大的频率偏差，AFC用于克服此频偏。
In wireless communication system, there is a large frequency bias between carrier frequency and local oscillating frequency. AFC is contributed to eliminate it.
如何克服这两个问题是OFDM技术研究的主要方向之一，本文主要是研究OFDM技术中的频率偏差估计问题。
How to eliminate the two problems is the main task of the research of OFDM. In this thesis, we mainly discuss the problem of frequency offset estimation.
通过两区域互联电网仿真实验，同其他频率偏差系数的设定方式进行了分析和比较，其结果表明了该方法的优越性。
Compared with other bias Settings in two-area interconnected power system model, the simulative results indicate the superiority of the proposed technique.
定时偏差会导致码间干扰，频率偏差会破坏子载波间的正交性，引起子载波间干扰，从而使系统整体性能急剧下降。
Timing offset causes inter-symbol interference, and frequency offset would destroy the orthogonality between subcarriers, causing ICI, which lead to a sharp decline in overall system performance.
目前，估计载波频率偏差和符号定时偏差的算法主要有数据辅助的方法和非数据辅助的方法以及基于循环前缀的算法。
Various existing synchronization algorithm to estimate symbol timing offset and carrier frequency offset can be classified into blind and pilot-aided methods and algorithm based on cyclic prefix.
理论分析和仿真表明这种方法具有较强的抗干扰性，其频率测量精度主要与信噪比、频率偏差及采样数据的长度有关。
In this paper, a phase difference correction method is presented to correct the power frequency. This method has strong anti-disturbance capability by theoretical analysis and simulation.
在上行链路中每个用户由于载波频率偏差而存在潜在的不同步，这样使子载波之间失去正交性，从而在基站接收端产生多用户间干扰。
However in uplink channel, each user has its own frequency offset which leads to a loss of orthogonality among the sub-carriers and multiuser interference at the base station receiver.
同时本文对电能质量的有关指标：电压偏差、频率偏差、各种功率、谐波含量、电压波动和三相不平衡的计算和检测方法，进行了详尽地阐述。
And some indexes of power quality: voltage deviation, real power, reactive power, harmonic content, voltage fluctuation and unbalanced three-phase voltage and current, are discussed at length.
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