| 摘要 |
The invention refers to single-ended test of a loop ( 2, 3 ). A test device (TD 1 ) is connected to a remote device ( 3 ) via a line ( 2 ). The remote device is powered on and transmits intermittently handshake signals (HS 1 ), which can disturb the loop test. A receiving and calculating unit (RE 1 ) detects the handshake signals (HS 1 ) and orders a sending unit (SD 1 ) to send a halting signal (NAK-EF) to the remote device. The latter is halted for predetermined silent period of time, during which the test or a part of it is performed. If required the halting of the handshake signals is repeated. The test device sends a broadband loop test signal (S 1 ) and receives a reflected signal (S 2 ) during the silent period. A frequency dependent echo transfer function is generated from the signals (S 1 , S 2 ) and is used for generating desired properties of the line ( 2 ) such as its length (L).
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