Method and apparatus for evaluating the integrity of the shield connection in a splicing section joining the ends of adjacent insulated and shielded communication cables

Claim 1

A method of evaluating the acceptable shielding integrity of the shield connection in a splice joining the adjacent ends of two insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; capacitively coupling a pair of spaced probes, equally sensitive to undesired noise signals induced on the cable shield and shield connection, across the questioned splice and adjacent to the input and output ends thereof; processing the noise signal picked up by each of said probes with reference to ground through a unity gain ultra-high impedance converting circuit into a low impedance output voltage; measuring the low impedance output voltage from each of said probes with respect to a common ground; any by comparing the differences between the output signal voltages from said spaced probes with respect to ground with a known standard, determining whether the installed splice meets required shielding standards, or may require repair.

Claim 2

A method of evaluating the acceptable shielding integrity of the shield connection in a splice joining the adjacent ends of two insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; capacitively coupling a pair of spaced probes, equally sensitive to undesired noise signals induced on the cable shield and shield connection, across the questioned splice and adjacent to the input and output ends thereof; processing the noise signal picked up by each of said probes with reference to ground through a unity gain ultra-high impedance converting circuit into a low impedance output voltage; measuring the low impedance output voltage from each of said probes with respect to a common ground; any by comparing the differences between the output signal voltages from said spaced probes with respect to ground with a known standard, determining whether the installed splice meets required shielding standards, or may require repair.

Claim 3

A method of evaluating the acceptable shielding integrity of the shield connection in a splice joining the adjacent ends of two insulated and shielded communication cable sections installed in the field, withoUt damage to the insulation, which includes; capacitively coupling a pair of spaced probes, equally sensitive to undesired noise signals induced on the cable shield and shield connection, across the questioned splice and adjacent to the input and output ends thereof; processing the noise signal picked up by each of said probes through a unity gain ultra-high impedance converting circuit to obtain a low impedance output voltage; measuring the low impedance output voltage differential between said spaced probes; and by comparing the measured voltage differential existing between said spaced probes with the known optimum voltage differential for a quality splice, determining whether the installed splice meets required shielding standards, or may require repair.

Claim 4

A method of evaluating the acceptable shielding integrity of the shield connection in a splice joining the adjacent ends of two insulated and shielded communication cable sections installed in the field, withoUt damage to the insulation, which includes; capacitively coupling a pair of spaced probes, equally sensitive to undesired noise signals induced on the cable shield and shield connection, across the questioned splice and adjacent to the input and output ends thereof; processing the noise signal picked up by each of said probes through a unity gain ultra-high impedance converting circuit to obtain a low impedance output voltage; measuring the low impedance output voltage differential between said spaced probes; and by comparing the measured voltage differential existing between said spaced probes with the known optimum voltage differential for a quality splice, determining whether the installed splice meets required shielding standards, or may require repair.

Claim 5

A method of evaluating the acceptable shielding integrity of the shield connection in a splice joining the adjacent ends of two insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; capacitively coupling a pair of spaced probes, equally sensitive to undesired noise signals induced on the cable shield and shield connection, across the questioned splice and adjacent to the input and output ends thereof; processing the noise signal picked up by each of said probes through a unity gain ultra-high impedance converting circuit to obtain a low impedance output voltage; measuring for reference use the low impedance output voltage between ground and one of said probes; measuring the low impedance output voltage differential between said spaced probes; and by comparing the measured voltage differential between said spaced probes, with the measured voltage between ground and one of said probes used as a reference, determining whether the installed splice meets required shielding standards, or may require repair.

Claim 6

A method of evaluating the acceptable shielding integrity of the shield connection in a splice joining the adjacent ends of two insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; capacitively coupling a pair of spaced probes, equally sensitive to undesired noise signals induced on the cable shield and shield connection, across the questioned splice and adjacent to the input and output ends thereof; processing the noise signal picked up by each of said probes through a unity gain ultra-high impedance converting circuit to obtain a low impedance output voltage; measuring for reference use the low impedance output voltage between ground and one of said probes; measuring the low impedance output voltage differential between said spaced probes; and by comparing the measured voltage differential between said spaced probes, with the measured voltage between ground and one of said probes used as a reference, determining whether the installed splice meets required shielding standards, or may require repair.

Claim 8

A method of evaluating the shielding integrity of the shield connection in a splice joining the adjacent ends of insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; initially capacitively coupling a pair of spaced probes, equally highly sensitive to undesired noise signals induced on the cable shield and shield connection, to an intact portion of said communication cable which is adjacent to the input end of said splice; measuring for reference use the voltage differential induced on the cable shield and picked up by said spaced probes as initially coupled; as a second step, capacitively coupling said spaced probes to the cable sections across the questioned splice and adjacent to the input and output ends of the splice; measuring the voltage differential induced on the splicing shield and picked up by said spaced probes as secondarily coupled; and evaluating the condition and quality of the questioned shield connection by comparing the measured voltage differential taken during said first coupling step, with the measured voltage differential taken during said second coupling step.

Claim 9

A method of evaluating the shielding integrity of the shield connection in a splice joining the adjacent ends of insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; initially capacitively coupling a pair of spaced probes, equally highly sensitive to undesired noise signals induced on the cable shield and shield connection, to an intact portion of said communication cable which is adjacent to the input end of said splice; measuring for reference use the voltage differential induced on the cable shield and picked up by said spaced probes as initially coupled; as a second step, capacitively coupling said spaced probes to the cable sections across the questioned splice and adjacent to the input and output ends of the splice; measuring the voltage differential induced on the splicing shield and picked up by said spaced probes as secondarily coupled; and evaluating the condition and quality of the questioned shield connection by comparing the measured voltage differential taken during said first coupling step, with the measured voltage differential taken during said second coupling step.

Claim 10

A method of evaluating the shielding integrity of the shield connection in a splice joining the adjacent ends of insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; initially capacitively coupling a pair of spaced probeS, equally highly sensitive to undersized noise signals induced on the cable shield and shield connection, to an intact portion of said communication cable which is adjacent to the input end of said splice; measuring for initial reference use the voltage differential induced on the cable shield and picked up by said spaced probes as initially coupled; as a second step, capacitively coupling said spaced probes to the cable sections across the questioned splice and adjacent to the input and output ends of the splice; during said second coupling step, measuring for secondary reference use the voltage induced on the cable shields and picked up by each of said probes with respect to a common ground; during said second coupling step, measuring the voltage differential induced on the splicing shield and picked up by said spaced probes; and evaluating the condition and quality of the questioned shield connection by comparing the measured voltage differential between said spaced probes and taken during said second coupling step, with (a) the reference voltage measurement made between each of said probes with respect to the common ground taken during said second coupling step, and also with (b) the measured voltage differential between said spaced probes and taken as a reference during said first coupling step.

Claim 11

A method of evaluating the shielding integrity of the shield connection in a splice joining the adjacent ends of insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; initially capacitively coupling a pair of spaced probeS, equally highly sensitive to undersized noise signals induced on the cable shield and shield connection, to an intact portion of said communication cable which is adjacent to the input end of said splice; measuring for initial reference use the voltage differential induced on the cable shield and picked up by said spaced probes as initially coupled; as a second step, capacitively coupling said spaced probes to the cable sections across the questioned splice and adjacent to the input and output ends of the splice; during said second coupling step, measuring for secondary reference use the voltage induced on the cable shields and picked up by each of said probes with respect to a common ground; during said second coupling step, measuring the voltage differential induced on the splicing shield and picked up by said spaced probes; and evaluating the condition and quality of the questioned shield connection by comparing the measured voltage differential between said spaced probes and taken during said second coupling step, with (a) the reference voltage measurement made between each of said probes with respect to the common ground taken during said second coupling step, and also with (b) the measured voltage differential between said spaced probes and taken as a reference during said first coupling step.

Claim 13

A method of evaluating the shielding integrity and grounding of the shield connection in a splice joining the adjacent ends of two insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; initially capacitively coupling a pair of spaced probes, equally highly sensitive to undesired noise signals induced on the cable shield and shield connection, to an intact portion of that communication cable section which is adjacent to the input end of said splice; as a second coupling step, capacitively coupling said spaced probes to the cable sections across the questioned splice and adjacent to the input and output ends of the splice; processing the noise signal picked up by each of said probes, during said initial coupling step and second coupling step, through a unity gain ultra-high impedance converting circuit to obtain a low impedance output voltage adapted for voltage measurement; during said initial coupling step, measuring for a first reference use, the voltage differential between the low impedance voltage outputs from said spaced probes, after processing through said noise signal converting circuits; during said initial coupling step, measuring for a second reference use, the low impedance voltage output from each of said spaced probes, after processing through said noise signal converting circuits, with respect to a common ground; during said second coupling step, measuring the voltage differential between the low impedance voltage outputs from said spaced probes, after processing through said noise signal converting circuits; and evaluating the condition and quality of the questioned shield connection and shield grounding by comparing the measured voltage differential between said spaced probes taken during said second coupling step, with (a) the measured voltage differential between said spaced probes taken as a first reference during said first coupling step, and also (b) with the measured voltages between each of said probes and the common ground taken as a second reference during said first coupling step.

Claim 14

A method of evaluating the shielding integrity and grounding of the shield connection in a splice joining the adjacent ends of two insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; initially capacitively coupling a pair of spaced probes, equally highly sensitive to undesired noise signals induced on the cable shield and shield connection, to an intact portion of that communication cable section which is adjacent to the input end of said splice; as a second coupling step, capacitively coupling said spaced probes to the cable sections across the questioned splice and adjacent to the input and output ends of the splice; processing the noise signal picked up by each of said probes, during said initial coupling step and second coupling step, through a unity gain ultra-high impedance converting circuit to obtain a low impedance output voltage adapted for voltage measurement; during said initial coupling step, measuring for a first reference use, the voltage differential between the low impedance voltage outputs from said spaced probes, after processing through said noise signal converting circuits; during said initial coupling step, measuring for a second reference use, the low impedance voltage output from each of said spaced probes, after processing through said noise signal converting circuits, with respect to a common ground; during said second coupling step, measuring the voltage differential between the low impedance voltage outputs from said spaced probes, after processing through said noise signal converting circuits; and evaluating the condition and quality of the questioned shield connection and shield grounding by comparing the measured voltage differential between said spaced probes taken during said second coupling step, with (a) the measured voltage differential between said spaced probes taken as a first reference during said first coupling step, and also (b) with the measured voltages between each of said probes and the common ground taken as a second reference during said first coupling step.

Claim 15

A method of evaluating the shielding integrity and grounding of the shield connection in a splice joining the adjacent ends of two insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; initially capacitively coupling a pair of spaced probes, equally highly sensitive to undesired noise signals induced on the cable shield and shield connection, to an intact portion of that communication cable section which is adjacent to the input end of said splice; as a second coupling step, capacitively coupling said spaced probes to the cable sections across the questioned splice and adjacent to the input and output ends of the splice; processing the noise signal picked up by each of said probes, during said initial coupling step and second coupling step, through a unity gain ultra-high impedance converting circuit to obtain a low impedance output voltage adapted for voltage measurement; during said initial coupling step, measuring for a first reference use, the voltage differential between the low impedance voltage outputs from said spaced probes, after processing through said noise signal converting circuits; during said initial coupling step, measuring for a second reference use, the low impedance voltage output from each of said spaced probes, after processing through said noise signal converting circuits, with respect to a common ground; during said second coupling step, and after processing through said noise signal converting circuits, measuring the voltage differential between the low impedance voltage outputs from said spaced probes, and also measuring the voltage outputs between each of said probes and the common ground; and evaluating the condition and quality of the questioned shield connection and shield grounding by comparing the measured voltage differential between said spaced probes, and the measured voltage outputs between each of said probes with respect to the common ground as taken during said second coupling step; with (a) the measured voltage differential between said spaced probes taken as a first reference during said first coupling step, and also (b) with the measured voltages between each of said probes and the common ground taken as a second reference during said first coupling step.

Claim 16

A method of evaluating the shielding integrity and grounding of the shield connection in a splice joining the adjacent ends of two insulated and shielded communication cable sections installed in the field, without damage to the insulation, which includes; initially capacitively coupling a pair of spaced probes, equally highly sensitive to undesired noise signals induced on the cable shield and shield connection, to an intact portion of that communication cable section which is adjacent to the input end of said splice; as a second coupling step, capacitively coupling said spaced probes to the cable sections across the questioned splice and adjacent to the input and output ends of the splice; processing the noise signal picked up by each of said probes, during said initial coupling step and second coupling step, through a unity gain ultra-high impedance converting circuit to obtain a low impedance output voltage adapted for voltage measurement; during said initial coupling step, measuring for a first reference use, the voltage differential between the low impedance voltage outputs from said spaced probes, after processing through said noise signal converting circuits; during said initial coupling step, measuring for a second reference use, the low impedance voltage output from each of said spaced probes, after processing through said noise signal converting circuits, with respect to a common ground; during said second coupling step, and after processing through said noise signal converting circuits, measuring the voltage differential between the low impedance voltage outputs from said spaced probes, and also measuring the voltage outputs between each of said probes and the common ground; and evaluating the condition and quality of the questioned shield connection and shield grounding by comparing the measured voltage differential between said spaced probes, and the measured voltage outputs between each of said probes with respect to the common ground as taken during said second coupling step; with (a) the measured voltage differential between said spaced probes taken as a first reference during said first coupling step, and also (b) with the measured voltages between each of said probes and the common ground taken as a second reference during said first coupling step.

Claim 17

An apparatus system for evaluating the shielding integrity and grounding of a questioned section of a shielded and insulated communication cable, which includes; a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to be applied in spaced relation to the cable across the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of the questioned section thereof to be evaluated; a shielding electrode insulated from said pickup electrode; and a unity gain high impedance converting circuit operative to translate the noise signals received by the pickup electrode into a low impedance output voltage adapted for voltage measurement, said converting circuit embracing an operational amplifier of voltage follower configuration having a non-inverting input terminal connected to said pickup electrode and an output terminal respectively connected to the inverting input terminal of said amplifier and to said shielding electrode and through a capacitor to the junction of a series pair of resistors connected between the pickup electrode and ground; and a voltage measuring instrument which includes a voltmeter connected in circuit through a rectifier bridge, operational amplifier and a transformer to the output terminals extending from the converting circuits in said probe heads.

Claim 18

An apparatus system for evaluating the shielding integrity and grounding of a questioned section of a shielded and insulated communication cable, which includes; a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to be applied in spaced relation to the cable across the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of the questioned section thereof to be evaluated; a shielding electrode insulated from said pickup electrode; and a unity gain high impedance converting circuit operative to translate the noise signals received by the pickup electrode into a low impedance output voltage adapted for voltage measurement, said converting circuit embracing an operational amplifier of voltage follower configuration having a non-inverting input terminal connected to said pickup electrode and an output terminal respectively connected to the inverting input terminal of said amplifier and to said shielding electrode and through a capacitor to the junction of a series pair of resistors connected between the pickup electrode and ground; and a voltage measuring instrument which includes a voltmeter connected in circuit through a rectifier bridge, operational amplifier and a transformer to the output terminals extending from the converting circuits in said probe heads.

Claim 20

An apparatus system for evaluating the shielding integrity and grounding of a questioned section of a shielded and insulated communication cable, which includes; a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to be applied in spaced relation to the cable across the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of the questioned section thereof to be evaluated; a shielding electrode insulated from said pick-up electrode; and a unity gain high impedance converting circuit operative to translate the noise signals received by the pickup electrode into a low impedance output voltage adapted for voltage measurement; and a voltage measuring instrument which embraces a three way switch presenting a pair of flexible contacts which normally connect the low impedance signal voltage output terminals of the converting circuits in said paired probe heads respectively through a pair of capacitors to the primary winding of a transformer, said three way switch having selective means for manipulating said flexible contacts into circuit with the signal voltage output terminal from one of said probes and ground, and for manipulating the said flexible contacts into circuit with the signal output voltage terminal from the other probe and ground, said transformer having the secondary winding thereof connected to the noninverting input terminal of a first stage operational amplifier and the output terminal of said first stage amplifier being connected to the inverting input terminal thereof and also to the noninverting input terminal of a second stage operational amplifier, the output terminal of said second stage amplifier being connected to the first input terminal of a rectifier bridge, the second input terminal of said rectifier bridge being connected to the inverting input of said second stage operational amplifier, a measuring meter having positive and negative power input terminals connected to the output terminals of said rectifier bridge, and a source of negative and positive direct current connected to and supplying operating power to said high impedance circuits associated with said probe heads and said first and second stage operational amplifiers of said measuring circuit.

Claim 21

An apparatus system for evaluating the shielding integrity and grounding of a questioned section of a shielded and insulated communication cable, which includes; a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to be applied in spaced relation to the cable across the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of the questioned section thereof to be evaluated; a shielding electrode insulated from said pick-up electrode; and a unity gain high impedance converting circuit operative to translate the noise signals received by the pickup electrode into a low impedance output voltage adapted for voltage measurement; and a voltage measuring instrument which embraces a three way switch presenting a pair of flexible contacts which normally connect the low impedance signal voltage output terminals of the converting circuits in said paired probe heads respectively through a pair of capacitors to the primary winding of a transformer, said three way switch having selective means for manipulating said flexible contacts into circuit with the signal voltage output terminal from one of said probes and ground, and for manipulating the said flexible contacts into circuit with the signal output voltage terminal from the other probe and ground, said transformer having the secondary winding thereof connected to the noninverting input terminal of a first stage operational amplifier and the output terminal of said first stage amplifier being connected to the inverting input terminal thereof and also to the noninverting input terminal of a second stage operational amplifier, the output terminal of said second stage amplifier being connected to the first input terminal of a rectifier bridge, the second input terminal of said rectifier bridge being connected to the inverting input of said second stage operational amplifier, a measuring meter having positive and negative power input terminals connected to the output terminals of said rectifier bridge, and a source of negative and positive direct current connected to and supplying operating power to said high impedance circuits associated with said probe heads and said first and second stage operational amplifiers of said measuring circuit.

Claim 22

An apparatus system for evaluating the shielding integrity and grounding of a questioned section of a shielded and insulated communication cable, which includes; a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to be applied in spaced relation to the cable across the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of the questioned section thereof to be evaluated; a shielding electrode insulated from said pickup electrode and a unity gain high impedance converting circuit operative to translate the noise signals received by the pickup electrode into a low impedance output voltage adapted for voltage measurement; and a measuring and calibrating instrument which includes a measuring circuit connected to the output terminals extending from the converting circuits in said probe heads, said measuring circuit embracing a voltage measuring meter presenting a decibel scale and an indicator manipulated by circuitry connecting the signal output terminals of said paired probe heads to said indicator, said circuitry embracing a transformer, an attenuator for calibrating said voltage measuring meter having adjustable means for connecting a selected attenuator terminal to the noninverting input terminal of a first stage operational amplifier, said first stage amplifier having an output terminal connected through a capacitor to the noninverting input terminal of a second stage operational amplifier, the outPut terminal of said second stage amplifier being connected to the first input terminal of a rectifier bridge, the second input terminal of said rectifier bridge being connected to the inverting input terminal of said second stage operational amplifier and also through a resistor to a common ground terminal, the output terminals of said rectifier bridge being connected to the input terminals of said measuring meter, and a direct current battery having positive and negative power output terminals connected to the power input terminals of the first stage and second stage operational amplifiers of said measuring circuitry, said positive and negative battery output terminals being also connected to the power input terminals of the operational amplifier of both probe head converting circuits.

Claim 23

An apparatus system for evaluating the shielding integrity and grounding of a questioned section of a shielded and insulated communication cable, which includes; a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to be applied in spaced relation to the cable across the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of the questioned section thereof to be evaluated; a shielding electrode insulated from said pickup electrode and a unity gain high impedance converting circuit operative to translate the noise signals received by the pickup electrode into a low impedance output voltage adapted for voltage measurement; and a measuring and calibrating instrument which includes a measuring circuit connected to the output terminals extending from the converting circuits in said probe heads, said measuring circuit embracing a voltage measuring meter presenting a decibel scale and an indicator manipulated by circuitry connecting the signal output terminals of said paired probe heads to said indicator, said circuitry embracing a transformer, an attenuator for calibrating said voltage measuring meter having adjustable means for connecting a selected attenuator terminal to the noninverting input terminal of a first stage operational amplifier, said first stage amplifier having an output terminal connected through a capacitor to the noninverting input terminal of a second stage operational amplifier, the outPut terminal of said second stage amplifier being connected to the first input terminal of a rectifier bridge, the second input terminal of said rectifier bridge being connected to the inverting input terminal of said second stage operational amplifier and also through a resistor to a common ground terminal, the output terminals of said rectifier bridge being connected to the input terminals of said measuring meter, and a direct current battery having positive and negative power output terminals connected to the power input terminals of the first stage and second stage operational amplifiers of said measuring circuitry, said positive and negative battery output terminals being also connected to the power input terminals of the operational amplifier of both probe head converting circuits.

Claim 25

An apparatus system for evaluating the shielding integrity and grounding of a questioned section of a shielded and insulated communication cable, which includes; a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to be applied in spaced relation to the cable across the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of the questioned section thereof to be evaluated; a shielding electrode insulated from said pickup electrode; and a unity gain high impedance converting circuit operative to translate the noise signals received by the pickup electrode into a low impedance output voltage adapted for voltage measurement, said converting circuit embracing an operational amplifier of voltage follower configuration having a noninverting input terminal connected to said pickup electrode and an output terminal respectively connected to the inverting input terminal of said amplifier and to said shielding electrode and through a capacitor to the junction of a series pair of resistors connected between the pickup electrode and ground; and an instrument which includes a measuring circuit connected to the output terminals extending from the converting circuits in said probe heads, said measuring circuit embracing a measuring meter presenting a decibel scale and an indicator manipulated by circuitry connecting the signal output terminals of said paired probe heads to said indicator, said circuitry embracing a transformer, an attenuator, adjustable means for connecting a selected attenuator terminal to the noninverting input terminal of a first stage operational amplifier, said first stage amplifier having an output terminal connected through a capacitor to the noninverting input terminal of a second stage operational amplifier, the output terminal of said second stage amplifier being connected to the first input terminal of a rectifier bridge, the second input terminal of said rectifier bridge being connected to the inverting input terminal of said second stage operational amplifier and also through a resistor to a common ground terminal, the output terminals of said rectifier bridge being connected to the input terminals of said measuring meter, and a direct current battery having positive and negative power output terminals connected to the power input terminals of the first stage and second stage operational amplifiers of said measuring circuitry, said positive and negative battery output terminals being also connected to the power input terminals of the operational amplifiers of both probe head converting circuits.

Claim 26

An apparatus system for evaluating the shielding integrity and grounding of a questioned section of a shielded and insulated communication cable, which includes; a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to be applied in spaced relation to the cable across the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of the questioned section thereof to be evaluated; a shielding electrode insulated from said pickup electrode; and a unity gain high impedance converting circuit operative to translate the noise signals received by the pickup electrode into a low impedance output voltage adapted for voltage measurement, said converting circuit embracing an operational amplifier of voltage follower configuration having a noninverting input terminal connected to said pickup electrode and an output terminal respectively connected to the inverting input terminal of said amplifier and to said shielding electrode and through a capacitor to the junction of a series pair of resistors connected between the pickup electrode and ground; and an instrument which includes a measuring circuit connected to the output terminals extending from the converting circuits in said probe heads, said measuring circuit embracing a measuring meter presenting a decibel scale and an indicator manipulated by circuitry connecting the signal output terminals of said paired probe heads to said indicator, said circuitry embracing a transformer, an attenuator, adjustable means for connecting a selected attenuator terminal to the noninverting input terminal of a first stage operational amplifier, said first stage amplifier having an output terminal connected through a capacitor to the noninverting input terminal of a second stage operational amplifier, the output terminal of said second stage amplifier being connected to the first input terminal of a rectifier bridge, the second input terminal of said rectifier bridge being connected to the inverting input terminal of said second stage operational amplifier and also through a resistor to a common ground terminal, the output terminals of said rectifier bridge being connected to the input terminals of said measuring meter, and a direct current battery having positive and negative power output terminals connected to the power input terminals of the first stage and second stage operational amplifiers of said measuring circuitry, said positive and negative battery output terminals being also connected to the power input terminals of the operational amplifiers of both probe head converting circuits.

Claim 27

An appaRatus system for evaluating the shielding integrity and grounding of a questioned section of a shielded and insulated communication cable, which includes; a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to be applied in spaced relation to the cable across the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of the questioned section thereof to be evaluated; a shielding electrode insulated from said pickup electrode; and a unity gain high impedance converting circuit operative to translate the noise signals received by the pickup electrode into a low impedance output voltage adapted for voltage measurement, said converting circuit embracing an operational amplifier of voltage follower configuration having a noninverting input terminal connected to said pickup electrode and an output terminal respectively connected to the inverting input terminal of said amplifier and to said shielding electrode and through a capacitor to the junction of a series pair of resistors connected between the pickup electrode and ground; and an instrument which includes a measuring circuit connected to the output terminals extending from the converting circuits in said probe heads, said measuring circuit embracing a transformer, an attenuator, an operational amplifier, a voltage measuring meter and a source of positive and negative direct current power connected to the operational amplifier in said probe heads and said measuring instrument. a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to beapplied in spaced relation to thecableacross the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of thequestioned section thereof to be evaluated; a shielding electrode insulated from saidpickup electrode;

Claim 28

An appaRatus system for evaluating the shielding integrity and grounding of a questioned section of a shielded and insulated communication cable, which includes; a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to be applied in spaced relation to the cable across the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of the questioned section thereof to be evaluated; a shielding electrode insulated from said pickup electrode; and a unity gain high impedance converting circuit operative to translate the noise signals received by the pickup electrode into a low impedance output voltage adapted for voltage measurement, said converting circuit embracing an operational amplifier of voltage follower configuration having a noninverting input terminal connected to said pickup electrode and an output terminal respectively connected to the inverting input terminal of said amplifier and to said shielding electrode and through a capacitor to the junction of a series pair of resistors connected between the pickup electrode and ground; and an instrument which includes a measuring circuit connected to the output terminals extending from the converting circuits in said probe heads, said measuring circuit embracing a transformer, an attenuator, an operational amplifier, a voltage measuring meter and a source of positive and negative direct current power connected to the operational amplifier in said probe heads and said measuring instrument. a pair of probe heads, equally sensitive to undesired noise signals induced on the cable shield, and designed to beapplied in spaced relation to thecableacross the questioned section thereof, each of said probe heads embracing a noise signal pickup electrode designed to be capacitively coupled to the communication cable adjacent an end of thequestioned section thereof to be evaluated; a shielding electrode insulated from saidpickup electrode;