Device for remotely testing a twisted pair transmission line

A communication system configured to selectively operate in a monitor mode and in a test mode, said communication system comprising:

• a twisted pair transmission line connected at a first end to a central office, said central office providing a first office battery voltage of a first polarity across said pair;
• and
• a two-wire POTS/xDSL network interface device connected to a second end of the twisted pair transmission line, said network interface device comprising:
• a bidirectional first port comprising first and second terminals establishing respective first and second voltage nodes;
• first and second switches electrically connected to said first and second terminals, respectively;
• a bidirectional second port comprising third and fourth terminals selectively connected to respective first and second terminals via respective first and second switches, said second port being connected to the first port when the device is in the monitor mode, and being disconnected from the first port when the device is in the test mode;
• a detector circuit connected in electrical parallel across said first and second voltage nodes and configured to detect a request signal, said detector circuit being further configured to output a first control signal to said first and second switches upon detection of said request signal, to thereby place the device in the test mode;
• a power supply circuit connected to said first port via said first and second switches, and arranged to output a DC supply voltage when the device is in the test mode, said power supply circuit being powered by a voltage applied across the first and second voltage nodes;
• and
• a signal generator circuit coupled to said first port via said first and second switches, and configured to output a predetermined test signal to said first port, when the device is in the test mode, said signal generator being powered by said DC supply voltage from said power supply circuit;
• and
• a control circuit configured to output a second control signal to said first and second switches to return the device to the monitor mode from the test mode.

A method of remotely testing a two-wire POTS/xDSL communication system which includes a twisted pair transmission line across which a first office battery voltage having a first polarity is normally applied, said method comprising the steps of:

• sending, from a first location remote from a customer's site, a request signal comprising a second battery voltage comprising a reversal in polarity of said first office battery voltage for at least a predetermined period of time, along the twisted pair transmission line and through a bidirectional first port at the customer's site;
• electrically isolating a customer's equipment from said twisted pair transmission line, in response to said request signal;
• receiving, at said first location, a test signal sent through said bidirectional first port and along the twisted pair transmission line from a point physically proximate to said customer's equipment, the test signal being sent automatically in response to said request signal;
• and
• analyzing said received test signal to assess the performance of the communication system.

A two-wire POTS/xDSL network interface device operable in one of a normal monitor mode and a test mode and configured to interface a twisted pair transmission line to customer equipment in a communication system, said network interface device comprising:

• a bidirectional first port comprising first and second terminals establishing respective first and second voltage nodes;
• first and second switches electrically connected to said first and second terminals, respectively;
• a bidirectional second port comprising third and fourth terminals selectively connected to respective first and second terminals via respective first and second switches, said second port being connected to the first port when the device is in the monitor mode, and being disconnected from the first port when the device is in the test mode;
• a detector circuit connected in electrical parallel across said first and second voltage nodes and configured to detect a request signal, said detector circuit being further configured to output a first control signal to said first and second switches upon detection of said request signal, to thereby place the device in the test mode;
• and
• a signal generator circuit coupled to said first port via said first and second switches, and configured to output a predetermined test signal to said first port, when the device is in the test mode;
• wherein
• the detector circuit is configured to detect a request signal which comprises a reversal in polarity of an office battery voltage applied across said first and second voltage nodes for a predetermined period of time.

A communication system configured to selectively operate in a monitor mode and in a test mode, said communication system comprising:

• a twisted pair transmission line connected at a first end to a central office, said central office providing a first office battery voltage of a first polarity across said pair;
• and
• a two-wire POTS/xDSL network interface device connected to a second end of the twisted pair transmission line, said network interface device comprising:
• a bidirectional first port comprising first and second terminals establishing respective first and second voltage nodes;
• first and second switches electrically connected to said first and second terminals, respectively;
• a bidirectional second port comprising third and fourth terminals selectively connected to respective first and second terminals via respective first and second switches, said second port being connected to the first port when the device is in the monitor mode, and being disconnected from the first port when the device is in the test mode;
• a detector circuit connected in electrical parallel across said first and second voltage nodes and configured to detect a request signal, said detector circuit being further configured to output a first control signal to said first and second switches upon detection of said request signal, to thereby place the device in the test mode;
• and
• a signal generator circuit coupled to said first port via said first and second switches, and configured to output a predetermined test signal to said first port, when the device is in the test mode;
• wherein
• said detector circuit is configured to detect a request signal comprising a second battery voltage comprising a reversal in polarity of said first office battery voltage applied across said pair, for a predetermined period of time.