US4220833A — Location of a faulty pulse form restorer in a cab…

Claim 1

Independent Claim 367 words

Apparatus for isolating a faulty pulse form restorer in a system having first and second terminals connected by a pair of transmission lines to normally transmit trains of pulses full duplex from sending means in each terminal to receiving means in the other terminal, with each transmission line having restorer units at intervals to regenerate the form of the pulses, power means to supply direct current from a terminal over a transmission line to provide power to the restorer units, each restorer unit having fault means which responds to the absence of a train of pulses to change by a fixed value the resistance of the direct current path through that restorer unit; said apparatus comprises: loop switching means operated for a test mode at the second terminal to couple the train of pulses from its receiving means to its sending means, and to make a direct current connection between the two transmission lines, so that a train of pulses from the sending means of the first terminal over one transmission line is returned over the other transmission line, direct current from the power means of the first terminal flows through the two transmission lines in series, and there is a chain of restorer units starting at the sending means of the first terminal out over the one transmission line and continuing back over the other transmission line; test clock means to interrupt the train of pulses in the sending means of the first terminal to have repetitive predetermined on and off intervals, whereby during the off intervals all restorer units of the two transmission lines have said change by a fixed value of the resistance of the direct current path, and during the on intervals only a faulty restorer unit and subsequent restorer units in the chain have said change; and fault locator means coupled to said power means in the first terminal to make a measurement which is a function of the difference between the resistance in the direct current path through the two transmission lines for said on and off intervals, and display means coupled to the detector means to display a number dependent on said measurement which indicates which restorer unit is faulty.

Claim 2

Dependent Claim 367 words

Apparatus for isolating a faulty pulse form restorer in a system having first and second terminals connected by a pair of transmission lines to normally transmit trains of pulses full duplex from sending means in each terminal to receiving means in the other terminal, with each transmission line having restorer units at intervals to regenerate the form of the pulses, power means to supply direct current from a terminal over a transmission line to provide power to the restorer units, each restorer unit having fault means which responds to the absence of a train of pulses to change by a fixed value the resistance of the direct current path through that restorer unit; said apparatus comprises: loop switching means operated for a test mode at the second terminal to couple the train of pulses from its receiving means to its sending means, and to make a direct current connection between the two transmission lines, so that a train of pulses from the sending means of the first terminal over one transmission line is returned over the other transmission line, direct current from the power means of the first terminal flows through the two transmission lines in series, and there is a chain of restorer units starting at the sending means of the first terminal out over the one transmission line and continuing back over the other transmission line; test clock means to interrupt the train of pulses in the sending means of the first terminal to have repetitive predetermined on and off intervals, whereby during the off intervals all restorer units of the two transmission lines have said change by a fixed value of the resistance of the direct current path, and during the on intervals only a faulty restorer unit and subsequent restorer units in the chain have said change; and fault locator means coupled to said power means in the first terminal to make a measurement which is a function of the difference between the resistance in the direct current path through the two transmission lines for said on and off intervals, and display means coupled to the detector means to display a number dependent on said measurement which indicates which restorer unit is faulty.

Claim 3

Dependent Claim 74 words

Apparatus as set forth in claim 1, for use with a system wherein said power means is a constant current source; wherein said fault locator means includes clamp means comprising clamp diodes coupled via a series capacitor to said power means, and a peak detector coupled to the clamp means, said measurement comprising the production of a peak detector output which is proportional to the peak-to-peak difference of the voltage at said power means.

Claim 4

Dependent Claim 53 words

Apparatus as set forth in claim 2, for use in a system wherein each pulse form restorer comprises two restorer units for the two directions of transmission, and a chart at the first terminal shows the relation of the number displayed to the location of the pulse form restorer having a faulty unit.

Claim 5

Dependent Claim 37 words

Apparatus as set forth in claim 2, wherein said first and second terminals are identical, and either may be used for the fault location and display as determined by the operative position of the loop switching means.

Claim 6

Dependent Claim 30 words

Apparatus as set forth in claim 2, wherein said fault locator means further includes a spike filter coupled between said power means and said series capacitor of the clamp means.

Claim 7

Dependent Claim 23 words

Apparatus as set forth in claim 5, wherein said spike filter comprises a pi arrangement of one shunt capacitor and a series resistor.

Claim 8

Dependent Claim 50 words

Apparatus as set forth in claim 5, including a switch connected between said series capacitor and said peak detector to provide a short circuit path when in an "off" position to thereby cause the said series capacitor of said clamp means to be initially charged to the power supply voltage.

Claim 9

Dependent Claim 20 words

Apparatus as set forth in claim 2, wherein said peak detector comprises active circuit means including operational amplifiers with feedback.

Claim 10

Dependent Claim 43 words

Apparatus as set forth in claim 2, wherein said fault locator means further includes analog-to-digital converter means connected to convert the output of said peak detector to a digital number, said display means being coupled to the output of the analog-to-digital converter means.

Claim 11

Dependent Claim 30 words

Apparatus as set forth in claim 9, wherein said analog-to-digital converter means includes up-down counting means controlled by clock signals and an operational amplifier circuit coupled to the peak detector.

Claim 12

Dependent Claim 31 words

Apparatus as set forth in claim 9, wherein said analog-to-digital converter includes an offset adjustment voltage divider to set the displayed number to "1" for the condition with no restorer units.

Claim 13

Dependent Claim 44 words

Apparatus as set forth in claim 11, further including a calibration adjustment voltage divider at the input of said peak detector for setting so that said display means displays a number designating the number of restorer units passing the train of pulses plus one.

Claim 14

Dependent Claim 104 words

Apparatus as set forth in claim 9, for use in a system wherein each restorer unit includes a precision resistor in the direct current path which is normally shunted by an electronic switch device, and said fault means in response to the absence of a train of pulses biases the electonic switch means to cut off, with a reference precision resistor also connected in series with the power means at said first terminal, all of said precision resistors having the same said fixed value; and said apparatus further includes reference circuit means coupling the voltage across said reference precision resistor to said analog-to-digital converter.

Claim 15

Dependent Claim 25 words

Apparatus as set forth in claim 13, wherein the coupling between the reference precision resistor and the analog-to-digital converter includes an inverting unity gain amplifier.

Claim 16

Dependent Claim 147 words

Apparatus for isolating a faulty unit in a system in which a plurality of units in tandem for signals are powered from a direct flow through said units in series, with fault means in each unit which responds to the absence of said signals to change the direct current resistance by a fixed value; said apparatus comprises: clocking means to periodically turn said signals on and off whereby the fault means of all units cause said change of resistance when the signals are off, and only a faulty unit and subsequent units cause said change of resistance when the signals are on; and fault locator means coupled to said direct current source to automatically make a peak-to-peak measurement which is a function of the total change of resistance through said units between the on and off intervals of said signals, to thereby indicate which unit is faulty.

Claim 17

Dependent Claim 147 words

Apparatus for isolating a faulty unit in a system in which a plurality of units in tandem for signals are powered from a direct flow through said units in series, with fault means in each unit which responds to the absence of said signals to change the direct current resistance by a fixed value; said apparatus comprises: clocking means to periodically turn said signals on and off whereby the fault means of all units cause said change of resistance when the signals are off, and only a faulty unit and subsequent units cause said change of resistance when the signals are on; and fault locator means coupled to said direct current source to automatically make a peak-to-peak measurement which is a function of the total change of resistance through said units between the on and off intervals of said signals, to thereby indicate which unit is faulty.

Claim 18

Dependent Claim 51 words

Apparatus as set forth in claim 15, for use in a system in which said direct current source is a constant current source, wherein said fault locator means includes clamp means coupled via a series capacitor to said direct current source, and an active peak detector coupled to the clamp means.

Claim 19

Dependent Claim 26 words

Apparatus as set forth in claim 16, wherein said fault locator means includes a spike filter coupled between the direct current source and said series capacitor.

Claim 20

Dependent Claim 43 words

Apparatus as set forth in claim 16, wherein said fault locator means further includes analog-to-digital converter means connected to convert the output of said peak detector to a digital number, said display means being coupled to the output of the analog-to-digital converter means.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1983-09-02	1984-03-03	1984-09-02	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1987-09-02	1988-03-03	1988-09-02	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1991-09-02	1992-03-03	1992-09-02	$7700.00	Window Closed / Lapsed

Location of a faulty pulse form restorer in a cable system

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