| 摘要 |
A loop polarity auto-reversing system 100 of a U interface is disposed in a line terminal 10 connected to a digital service unit 20 via the U interface. The loop polarity auto-reversing system includes a current detection module 101 , a loop polarity determining module 103 , and a loop polarity reversing module 105 . The current detection module is for detecting whether there is loop current at the U interface. The loop polarity determining module is for determining whether a loop polarity of the U interface is correct if there is loop current. The loop polarity reversing module is for reversing the loop polarity of the U interface if the loop polarity is incorrect. An auto-reversing method for reversing the loop polarity of the U interface is also provided.
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