Method for testing network transmission line using time-domain signal

A network transmission and time-domain signal technology, applied in the transmission system, digital transmission system, data exchange network, etc., can solve the problems of poor anti-interference ability, poor resolution of continuous impedance transformation points, long test time, etc., to achieve The effect of strong resolution and strong anti-interference ability

Inactive Publication Date: 2007-08-22
HUAWEI TECH CO LTD
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Problems solved by technology

Only one or two impedance transformation points can be measured at a time, and the test time is relatively long;
[0006] 2. The ability to distinguish continuous impedance transformation points is relatively poor, and the impedance transformation points that are relatively close are often considered to be only one
[0007] 3. The anti-interference ability is poor, and the correct test cannot be carried out in the case of complicated line noise

Method used

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  • Method for testing network transmission line using time-domain signal
  • Method for testing network transmission line using time-domain signal
  • Method for testing network transmission line using time-domain signal

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Experimental program
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Embodiment Construction

[0041] 1. The CHIRP signal is used as the original sending signal and the basic algorithm principle description:

[0042] The continuous impedance transformation point can be correctly distinguished by the TDR test method, but if the distance between the two impedance transformation points is 200 meters, then the maximum length of the original transmitted signal is 1us when the time aliasing of the two reflected signals does not occur. For example, if a 1MHz sinusoidal signal is used, only one cycle length can be used. Even if the echo signal is received at the receiving end, it is difficult to correctly distinguish the continuous impedance transformation point.

[0043] The CHIRP signal is used as the sending signal for the TDR test of the network transmission line. Referring to Figure 2, the autocorrelation of the CHIRP signal is relatively strong, and the time compression of more than 1 / 16 can be achieved on the user twisted pair line. The waveform reflected from the line i...

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Abstract

This invention discloses a method for TDR test to the network transmission circuit with the CHIRP signal as the original transmission signal including: first of all, generating a CHIRP transmission signal used in network transmission line TDR test to be amplified and driven to the test line, receiving the echo data from the test line then carrying out co-related operation to CHIRP transmission signal and the echo data then cutting the operation result via a fixed threshold to get the impedance conversion point of the test line finally. This invention applies CHIRP signal as the send signal of TDR test, it's not necessary to make repeated detected tests when the length of the tested line is unknown due to the strong autocorrelation of the CHIRP signal.

Description

technical field [0001] The invention belongs to the technical field of testing the length, frequency response and the like of network lines by means of time domain reflection (TDR), and in particular relates to a method for performing TDR testing on network transmission lines by using CHIRP signals as test signals. Background technique [0002] TDR test is a method that uses the reflection of the transmission line to test the unknown characteristics of the line and calculate most of the characteristics of the line. The test time is short and the accuracy is high. It has important practical value for large central office equipment such as DSLAM. . This method utilizes the characteristics of the time-domain signal reflected on the transmission line, and estimates the characteristics of the transmission line according to various characteristics of the received echo signal. Referring to Figure 1, the sending module is used to generate a waveform to be sent, which is transformed...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L12/26
Inventor 方李明
Owner HUAWEI TECH CO LTD
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