Method and apparatus for self-testing a customer services terminal and for loop testing telephone lines that are connected thereto
View Patent ↗A telecommunications system includes a telephone exchange and a customer services terminal whose input is connected to the telephone exchange, and whose plural outputs are individually connected to one of a plurality of telephone lines. A plurality of interface circuits within the customer services terminal are individually connected intermediate the input and one of the plural outputs. Self-test means provides for the testing of selected interface circuits. Loop-test means provides for the testing of selected telephone lines. A self-test relay is responsive to the self-test means and operates to disconnect the selected outputs from corresponding telephone lines as self-test conditions are applied to selected interface circuits as these interface circuits are disconnected from the selected telephone lines. The loop test means applies loop-test conditions to selected interface circuits, while the selected interface circuits and the corresponding outputs remain connected to the corresponding telephone lines. In either case, other interface circuits, outputs, and telephone lines that are not undergoing test remain operative to supply telecommunications services between the telephone exchange and these other telephone lines.
1. A telecommunications system comprising:
a telephone exchange;
a customer services terminal having an input connected to said telephone exchange, and having a plurality of outputs individually connected to one of a plurality of telephone lines;
a plurality of interface circuits within said customer services terminal, each of said interface circuits being connected to one of said plurality of outputs;
self-test means for testing said interface circuits;
loop-test means for testing said telephone lines;
a self-test relay responsive to said self-test means and operative during a self-test to disconnect said plurality of outputs from said plurality of telephone lines, and to provide self-test conditions to said interface circuits while said interface circuits are disconnected from said plurality of telephone lines;
means responsive to said loop-test means, operative to provide loop-test conditions to said interface circuits while said plurality of interface circuits and said plurality of outputs remain connected to said plurality of telephone lines;
selecting means for selecting certain of said interface circuits and/or certain of said telephone lines to which said self-test conditions and/or said loop-test conditions are to be applied, while a remainder of said interface circuits and/or a remainder of said telephone lines remain operative with said telephone exchange;
a first tip lead and a first ring lead forming each of said plurality of telephone lines;
a second tip lead and a second ring lead forming each of said plurality of outputs;
a first and second normally-closed self-test relay switch respectively operative to connect said first tip lead to said second tip lead and to connect said first ring lead to said second ring lead when said self-test relay is de-energized during a loop-test;
a first and second normally-open self-test relay switch respectively operative to disconnect said first tip lead from said second tip lead and to disconnect said first ring lead from said second ring lead when said self-test relay is energized during a self-test;
a loop start relay operative when energized during certain self-tests to connect a termination impedance from said second tip lead to said second ring lead; and
a ground start relay operative when energized during other self-tests to connect said second ring lead to a source of ground potential as said second tip lead is maintained in a disconnected condition.
2. The telecommunication system of claim 1 including:
a plurality of over-current protection devices individually connected in series with each of said second tip leads and said second ring leads; and
a plurality of over-voltage protection devices individually connected from each of said second tip leads to each of said second ring leads.
3. The telecommunications system of claim 2 wherein each of said over-voltage protection device is located adjacent to a corresponding interface circuit, and wherein each of said over-current protection devices is located to respond to a high current flow caused by operation of a corresponding over-voltage protection device.
4. The telecommunications system of claim 3 wherein:
said loop-tests include one or more of (1) testing for a short circuit between a selected first tip lead and a corresponding first ring lead, (2) testing for the connection of a selected first tip lead and/or a corresponding first ring lead to a voltage source that should not exist in said telecommunications system, (3) testing for the short-circuiting of a selected first tip lead to an associated first ring lead as is provided by simulating an off-hook condition of an associated telephone, and (4) testing for an open circuit of said a selected first tip lead and/or a corresponding first ring lead; and
said self-tests include one of more of (1) testing for circuit continuity from a selected second tip lead to a corresponding second ring lead through a corresponding termination impedance, (2) testing for connection of a selected second ring lead to ground potential, (3) applying a test tone to a selected second ring lead and its corresponding tip lead and detecting a transmit gain and/or a receive gain of an associated interface circuit, (4) applying a test tone to a selected second ring lead and its corresponding tip lead and detecting a trans-hybrid loss of an associated interface circuit, and (5) applying a test tone to a selected second ring lead and its corresponding tip lead and detecting a ringing signal by an associated interface circuit.
5. A customer services terminal for use in a telecommunications system comprising:
an input for connection to a telephone exchange;
a plurality of outputs for individual connection to one of a plurality of telephone lines;
a plurality of interface circuits, each of said interface circuits being connected to one of said plurality of outputs;
self-test means for testing said interface circuits;
loop-test means for testing said telephone lines;
a self-test relay responsive to said self-test means and operative during a self-test to disconnect said plurality of outputs from the plurality of telephone lines and to provide self-test conditions to said interface circuits while said interface circuits are disconnected from the plurality of telephone lines;
means responsive to said loop-test means, operative to provide loop-test conditions to said interface circuits while said plurality of interface circuits and said plurality of outputs remain connected to the plurality of telephone lines;
selecting means for selecting certain of said interface circuits and/or certain of the telephone lines to which said self-test conditions and/or said loop-test conditions are to be applied, while a remainder of said interface circuits and/or a remainder of the telephone lines remain operative with the telephone exchange;
a first tip lead and a first ring lead forming each of the plurality of telephone lines;
a second tip lead and a second ring lead forming each of said plurality of outputs;
a first and second normally-closed self-test relay switch respectively operative to connect a first tip lead to a corresponding second tip lead and to connect a first ring lead to corresponding second ring lead when said self-test relay is deenergized during a loop-test;
a first and second normally-open self-test relay switch respectively operative to disconnect a first tip lead from a corresponding second tip lead and to disconnect a first ring lead from a corresponding second ring lead when said self-test relay is energized during a self-test;
a loop-start relay operative when energized during certain self-tests to connect a termination impedance from a second tip lead to a corresponding second ring lead; and
a ground-start relay operative when energized during other self-tests to connect a second ring lead to a source of ground potential as a corresponding second tip lead is maintained in a disconnected condition.
6. The customer services terminal of claim 5 including:
a plurality of over-current protection devices individually connected in series with each of said second tip leads and said second ring leads; and
a plurality of over-voltage protection devices individually connected from each of said second tip leads to each of said second ring leads.
7. The customer services terminal of claim 6 wherein each of said over-voltage protection device is located adjacent to a corresponding interface circuit, and wherein each of said over-current protection devices is located to respond to a high current flow caused by operation of a corresponding over-voltage protection device.
8. The customer services terminal of claim 7 wherein;
said loop-tests include one or more of (1) testing for a short circuit between a selected first tip lead and a corresponding first ring lead, (2) testing for the connection of a selected first tip lead and/or a corresponding first ring lead to a voltage source that should not exist in said telecommunications system, (3) testing for the short circuiting of a selected first tip lead to an associated first ring lead as is provided by simulating an off-hook condition of an associated telephone, and (4) testing for an open circuit of said selected first tip lead and/or a corresponding first ring lead; and
said self-tests include one of more of (1) testing for circuit continuity from a selected second tip lead to a corresponding second ring lead through a corresponding termination impedance, (2) testing for connection of a selected second ring lead to ground potential, (3) applying a test tone to a selected second ring lead and its corresponding tip lead and detecting a transmit gain and/or a receive gain of an associated interface circuit, (4) applying a test tone to a selected second ring lead and its corresponding tip lead and detecting a trans-hybrid loss of an associated interface circuit, and (5) applying a test tone to a selected second ring lead and its corresponding tip lead, and detecting a ringing signal by an associated interface circuit.