ADSL Line Testing Technology

As a transmission technology based on common telephone twisted pair wires, ADSL is highly dependent on physical transmission lines. The characteristics of the Loop will have a decisive impact on the quality and performance of the ADSL service. First, you will encounter problems such as how to select the ADSL line, whether a line can activate the ADSL service, how fast it can be activated, and the reasons that affect the transmission quality. In addition, problems such as how to find, judge, and eliminate problems that may cause poor transmission quality or obstacles during routine maintenance must be tested on the ADSL line.

The automatic test function of ADSL involves two technologies:

1. Single-ended testing technology (SELT)

The Test Technology of ADSL lines generally includes single-ended and double-ended tests. The dual-end test refers to the test that requires the cooperation of the CPE device on the user end, and the content that can be tested also has some limitations. It can preliminarily determine the status of the line and perform simple fault locating. It is a simple and effective method when the network capacity is small and the number of users is small. A single-ended test is a line test initiated by the local terminal without the need of the user's terminal devices. It can measure the line length, line gauge, background noise spectrum, line attenuation, and estimated maximum possible rate. It is suitable for Line Selection and daily operation and maintenance. The single-ended test is unrelated to the user's terminal device. No matter what model the user's terminal device is, or whether the user's terminal device is enabled, the test can accurately test the broadband parameters of the user's line, high test efficiency. Therefore, the single-ended testing technology will be the development direction of ADSL line testing.

2. Automatic Wire capturing technology for DSLAM Devices

For a single-ended downlink test, the DSLAM device must have the automatic wire capturing function. That is to say, the DSLAM device must have a test bus and provide a test communication interface with the test device, when you need to test a user, you can switch the inner or outer side of the user port to the test bus, and then start the test device for testing. Otherwise, the cables must be manually mounted to the distribution frame, which is inefficient and cannot be commercially available.