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Digital automatic frequency control loop-locking decision method

An automatic frequency control and loop technology, applied in digital transmission systems, electrical components, transmission systems, etc., can solve the problems of high probability of misjudgment, reduce the probability of misjudgment, make the judgment method simple and accurate, and strengthen constraints conditional effect

Inactive Publication Date: 2003-03-19
HUAWEI TECH CO LTD
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Problems solved by technology

[0003] The purpose of the present invention is to overcome the defects of high probability of misjudgment in the above-mentioned prior art, and provide a more accurate and real-time new type of digital automatic frequency control loop locking judgment that is not affected by the amplitude fading characteristics of the input signal. method

Method used

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  • Digital automatic frequency control loop-locking decision method
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  • Digital automatic frequency control loop-locking decision method

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Embodiment Construction

[0019] figure 1 is a block diagram of a lock judgment circuit used in a traditional lock judgment method. Such as figure 1 As shown, the judgment method adopted by the traditional lock judgment circuit is the characteristic of the cosine of the loop error signal. The basic principle is that when the loop is locked, the error signal θ e small, cosθ e =1, the output value of the low-pass filter is relatively large, and when the output value is greater than a certain appropriate threshold, it is considered that the loop is locked. However, in mobile communication channels, affected by Rayleigh fading, even if the loop is locked, but because the signal amplitude is low and the output value of the auxiliary phase detector is small, this method will be misjudged as a loop Unlocked, or the loop is not locked, but the signal amplitude is relatively high, and the output value of the auxiliary phase detector is relatively large. This method will be misjudged as loop locked. Even if ...

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Abstract

The present invention discloses a new locking judgement method for digital automatic frequency controlled loop. It includes the steps as the follows: to calculate out the average value y(k) of N numbers of input signals, to compare the sizes of input signals, to input the kept peak value into JI as jitter, to calculate out the absolute value of the difference between the present obtained peak value jitter JI and the last time obtained peak value jitter PJI and to make the comparasion between the difference absolute value and peak value threshold value. The method judges whether the loop is locked or not by counting up the curve characters of closed loop response character in loops and it does not to be influenced by the variation of inputted signal amplitude.

Description

technical field [0001] The invention relates to the technical field of synchronous application in a communication system, and more specifically relates to a digital automatic frequency control loop locking technology. technical background [0002] The lock judgment circuit is an important part in the automatic frequency control (AFC) loop and phase-locked loop circuit. It is mainly used in carrier recovery and frequency tracking to provide real-time and effective loop status information for the normal operation of the system. The judgment method adopted by the traditional lock judgment circuit is the characteristic of the cosine of the loop error signal. The basic principle is that when the loop is locked, the error signal θ e small, cosθ e =1, the output value of the low-pass filter is relatively large, and when the output value is greater than a certain appropriate threshold value, it is considered that the loop is locked. But in the mobile communication channel, due to...

Claims

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Application Information

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IPC IPC(8): H04L7/02
Inventor 冯淑兰
Owner HUAWEI TECH CO LTD
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