Procedure and apparatus for locating faults in digital repeatered lines

Claim 2

In a communications system the combination comprising a central station, a remote station a transmit line extending from the central station to the remote station, a receive line extending from the remote station to the central station, two transmit sets of repeaters serially connected in the transmit line at spaced positions, two receive sets of repeaters serially connected in the receive line at spaced positions, means including a test signal generator at the central station for selectively generating a predetermined limited number of test signals and for applying the test signals to the transmit line, the test signals being in the form of bipolar pulse trains having bipolar violations therein for imparting respective frequency characteristics to said test signal, a fault line extending from all of the repeaters to the central station, each set of repeaters being respectively connected to the fault line via a corresponding set of band pass filters tailored to pass respective ones of the frequency characteristics, means at the central station for applying a ''''set selector'''' signal to the fault line and including responsive means at the repeaters for enabling the repeater sets in the respective lines to respond separately to the test signals thereby doubling the number of repeaters which can be tested with the same set of test signals, a test signal encoding device at the central station interposable between the test signal generator means and the transmit line including pulse polarity reversal means for removing said bipolar violations and encoding the test signals into a disguisEd form free of said frequency characteristics, and a test signal decoding device at the remote station interposable between the transmit line and the receive line for reconverting the encoded test signals into test signals of directly usable form including said bipolar violations and the respective frequency characteristics imparted thereby, so that by interposition of the encoder and decoder a total number of repeaters can be tested using the same fault line which is four times as great as the available number of test signals.

Claim 3

The combination as claimed in claim 1 in which the set selector signal applied at the central station to the fault line is in the form of a D.C. polarity.

Claim 4

In a communications system the combination comprising a central station, a remote station, a transmit line extending from the central station to the remote station, a receive line extending from the remote station to the central station, a transmit set of repeaters serially connected in the transmit line, a receive set of repeaters serially connected in the receive line, a test signal generator at the central station for selectively generating a predetermined limited number of test signals in directly usable form and for applying said test signals to the transmit line, said test signals being in the form of a series of pulses having periodic bipolar violations for imparting respective frequency characteristics to said test signals, encoding means interposable between the test signal generator and the transmit line and including pulse polarity reversal means for removing said bipolar violations and encoding said test signals into disguised form consisting of a series of pulses free of said frequency characteristics, a fault line leading from the repeaters to the central station, a set of band pass filters tailored to pass respective ones of the frequency characteristics, each band pass filter being interposed between the output side of a transmit and receive repeater and the fault line so that each transmit repeater may be tested by the test signals which are in directly usable form, a test signal decoder at the remote station responsive to the receipt of the test signals in coded form for decoding such test signals and for applying the decoded signals including the bipolar violations and the frequency characteristics imparted thereby to the receive line for separate testing of the repeaters in the receive line.

Claim 5

In a communications system the combination comprising a central station, a remote station, a transmit line extending from the central station to the remote station, a receive line extending from the remote station to the central station, a transmit set of repeaters serially connected in the transmit line, a receive set of repeaters serially connected in the receive line, a test signal generator at the central station for selectively generating a predetermined limited number of test signals in directly usable form and for applying said test signals to the transmit line, said test signals being in the form of a series of pulses having periodic bipolar violations for imparting respective frequency characteristics to said test signals, encoding means interposable between the test signal generator and the transmit line and including pulse polarity reversal means for removing said bipolar violations and encoding said test signals into disguised form consisting of a series of pulses free of said frequency characteristics, a fault line leading from the repeaters to the central station, a set of band pass filters tailored to pass respective ones of the frequency characteristics, each band pass filter being interposed between the output side of a transmit and receive repeater and the fault line so that each transmit repeater may be tested by the test signals which are in directly usable form, a test signal decoder at the remote station responsive to the receipt of the test signals in coded form for decoding such test signals and for applying the decoded signals including the bipolar violations and the frequency characteristics imparted thereby to the receive line for separate testing of the repeaters in the receive line.

Claim 6

The combination as claimed in claim 3 in which the directly usable test signal consists of a patterned series of pulses in which the positive pulses predominate followed by a patterned series of equal duration in which the negative pulses predominate, the two series being sent repetitively to produce a sensible frequency which corresponds to the repetition rate.

Claim 7

The combination as claimed in claim 4 in which one series of pulses is made up of positive pulse trios having two positive pulses and one negative pulse and in which the succeeding series is made up of negative pulse trios formed of two negative pulses and one positive pulse.

Claim 8

The combination as claimed in claim 5 in which the number of trios of given polarity in each series is progressively increased while maintaining the same series repetition rate, the number of trios which can be accommodated before breakdown serving as a figure of merit for each repeater.

Claim 9

The combination as claimed in claim 4 in which means are provided for encoding the test signal as a train of bipolar pulses devoid of any characteristic frequency within the pass bands of the filters.

Claim 10

The combination as claimed in claim 3 in which the directly usable test signal consists of a train of pulses in which pulses of one polarity predominate in a repetitive pattern at a characteristic frequency.

Claim 11

In a communications system the combination comprising a central station, a remote station, a transmit line extending from the central station to the remote station, a receive line extending from the remote station to the Central station, a transmit set of repeaters serially connected in the transmit line at spaced positions, a receive set of repeaters serially connected in the receive line at correspondingly spaced positions, means including a test signal generator at the central station for selectively generating test signals in directly usable form and for applying the test signals to the transmit line, the test signals being in the form of pulse trains including trios and duos alternating to impart resepctive frequency characteristics to said test signal, a fault line extending from all of the repeaters to the central station, a set of band pass filters constructed to pass respective ones of the frequency characteristics with individual band pass filters being coupled between the output sides of corresponding ones of the spaced repeaters and the fault line, a test signal encoding device at the central station interposable between the test signal generator and the transmit line for encoding the test signals including said trios and duos into a disguised form free of said frequency characteristics, a test signal decoding device at the remote station connected between the transmit line and the receive line, the decoding device serving to reconvert the coded test signals into test signals of directly usable form including said trios and duos and having the respective frequency characteristics so that the same test signal generator means can be used for testing of the transmit repeaters and, by interposition of the encoder device, for testing of the receive repeaters.

Claim 12

In a communications system the combination comprising a central station, a remote station, a transmit line extending from the central station to the remote station, a receive line extending from the remote station to the Central station, a transmit set of repeaters serially connected in the transmit line at spaced positions, a receive set of repeaters serially connected in the receive line at correspondingly spaced positions, means including a test signal generator at the central station for selectively generating test signals in directly usable form and for applying the test signals to the transmit line, the test signals being in the form of pulse trains including trios and duos alternating to impart resepctive frequency characteristics to said test signal, a fault line extending from all of the repeaters to the central station, a set of band pass filters constructed to pass respective ones of the frequency characteristics with individual band pass filters being coupled between the output sides of corresponding ones of the spaced repeaters and the fault line, a test signal encoding device at the central station interposable between the test signal generator and the transmit line for encoding the test signals including said trios and duos into a disguised form free of said frequency characteristics, a test signal decoding device at the remote station connected between the transmit line and the receive line, the decoding device serving to reconvert the coded test signals into test signals of directly usable form including said trios and duos and having the respective frequency characteristics so that the same test signal generator means can be used for testing of the transmit repeaters and, by interposition of the encoder device, for testing of the receive repeaters.

Claim 13

The combination as claimed in claim 9 in which an additional set of transmit and receive repeaters are serially connected at spaced positions in the transmit and receive lines respectively and a corresponding set of band pass filters are connected to the same fault line, and means are provided including switches operated by a signal applied to the fault line at the central station for selectively actuating the sets of band pass filters for response to a test signal.

Claim 14

In a communications system the combination comprising a central station, a remote station, a transmit line extending from the central station to the remote station, a receive line extending from the remote station to the central station, a transmit set of repeaters serially connected in the transmit line, a receive set of repeaters serially connected in the receive line, means including a test signal generator at the central station for selectively generating test signals in directly usable form and for applying the test signals to the transmit line, the test signals being in the form of pulse trains including a plurality of pulse pattern types with the pattern types alternating to impart respective frequency characteristics to said test signal, a fault line extending from the repeaters to the central station, a set of band pass filters respectively coupled between the output sides of the repeaters and the fault line, the band pass filters being tailored to pass respective ones of the frequency characteristics to the fault line for individual testing of the transmit repeaters by the test signals, a test signal encoding device at the central station interposable between the test signal generator and the transmit line for selectively converting the test signals into pulse trains having no sensible frequency characteristic, said test signal encoding device including means for generating a transition signal in response to transitions between said pattern types in said test signal, a test signal decoding device at the remote station interposable between the transmit line and the receive line and responsive to said transition signal for converting the coded test signals back into test signals of directly usable form having the respective frequency characteristics for separate testing of the repeaters in the receive line.

Claim 15

In a communications system the combination comprising a central station, a remote station, a transmit line extending from the central station to the remote station, a receive line extending from the remote station to the central station, a transmit set of repeaters serially connected in the transmit line, a receive set of repeaters serially connected in the receive line, means including a test signal generator at the central station for selectively generating test signals in directly usable form and for applying the test signals to the transmit line, the test signals being in the form of pulse trains including a plurality of pulse pattern types with the pattern types alternating to impart respective frequency characteristics to said test signal, a fault line extending from the repeaters to the central station, a set of band pass filters respectively coupled between the output sides of the repeaters and the fault line, the band pass filters being tailored to pass respective ones of the frequency characteristics to the fault line for individual testing of the transmit repeaters by the test signals, a test signal encoding device at the central station interposable between the test signal generator and the transmit line for selectively converting the test signals into pulse trains having no sensible frequency characteristic, said test signal encoding device including means for generating a transition signal in response to transitions between said pattern types in said test signal, a test signal decoding device at the remote station interposable between the transmit line and the receive line and responsive to said transition signal for converting the coded test signals back into test signals of directly usable form having the respective frequency characteristics for separate testing of the repeaters in the receive line.

Claim 16

In a communications system the combination comprising a central station, a remote station, a transmit line extending from the central Station to the remote station, a receive line extending from the remote station to the central station, a transmit set of repeaters serially connected in the transmit line at spaced positions, a receive set of repeaters serially connected in the receive line at spaced positions, means including a test signal generator at the central station for selectively generating a predetermined limited number of test signals in directly usable form and for applying the test signals to the transmit line, the test signals being in the form of bipolar pulse trains having periodic bipolar violations for imparting respective frequency characteristics to said test signal, a fault line extending from all of the repeaters to the central station, a set of band band pass constructed to pass respective ones of the frequency characteristics and respectively connected between the output sides of the repeaters and the fault line, a test signal encoding device at the central station interposable between the test signal generator means and the transmit line and including pulse polarity reversal means for removing said bipolar violations and encoding the test signals into disguised form consisting of trains of bipolar pulses free of the respective frequency characteristics, a test signal decoding device at the remote station for restoring the disguised test signals into a directly usable form including said bipolar violations and having the respective frequency characteristics, and means including a switch associated with the decoding device responsive to the arrival of an encoded pulse train for connecting the output of the decoding device to the receive line for testing of the repeaters in the receive line.

Claim 17

In a communications system the combination comprising a central station, a remote station, a transmit line extending from the central Station to the remote station, a receive line extending from the remote station to the central station, a transmit set of repeaters serially connected in the transmit line at spaced positions, a receive set of repeaters serially connected in the receive line at spaced positions, means including a test signal generator at the central station for selectively generating a predetermined limited number of test signals in directly usable form and for applying the test signals to the transmit line, the test signals being in the form of bipolar pulse trains having periodic bipolar violations for imparting respective frequency characteristics to said test signal, a fault line extending from all of the repeaters to the central station, a set of band band pass constructed to pass respective ones of the frequency characteristics and respectively connected between the output sides of the repeaters and the fault line, a test signal encoding device at the central station interposable between the test signal generator means and the transmit line and including pulse polarity reversal means for removing said bipolar violations and encoding the test signals into disguised form consisting of trains of bipolar pulses free of the respective frequency characteristics, a test signal decoding device at the remote station for restoring the disguised test signals into a directly usable form including said bipolar violations and having the respective frequency characteristics, and means including a switch associated with the decoding device responsive to the arrival of an encoded pulse train for connecting the output of the decoding device to the receive line for testing of the repeaters in the receive line.

Claim 18

The combination as claimed in claim 12 in which the initial portion of the encoded pulse train includes an encoded switching instruction and in which the switching means includes means for responding to the switching instruction.

Claim 19

In a communications system the combination comprising a central station, a remote station, a transmit line extending from the central station to the remote station and a receive line extending from the remote station to the central station, a transmit set of repeaters serially connected in the transmit line at spaced positions, a receive set of repeaters serially connected at the receive line at spaced positions, means including a test signal generator for selectively generating predetermined limited number of test signals in the form of pulse trains including trios and duos and having respective frequency characteristics in a form directly usable for testing the repeaters in the transmit line, a fault line extending from the repeaters to the central station, a set of band pass filters respectively connected between the output sides of the repeaters and the fault line, the band pass filters being tailored to pass respective ones of the frequency characteristics to the fault line for detection at the central station, the number of repeaters in the transmit set exceeding the number of test signals so that at least two of the transmit repeaters are associated with band pass filters which are duplicatedly responsive to the same frequency characteristic, means in the central station for selectively applying an enabling signal to the fault line, and means including a switch associated with the duplicated band pass filters and responsive to the enabling signal for coupling a selected one of such duplicated filters to the fault line, a test signal encoding device at the central station coupled to the test signal generating means for encoding the test signals into a disguised form free of said frequency characteristics, and a test signal decoding device at the remote station for receiving the disguised test signals and reconverting them back into directly usable form including said trios and duos for application to the receive line for testing of the repeaters in the receive line.

Claim 20

In a communications system the combination comprising a central station, a remote station, a transmit line extending from the central station to the remote station and a receive line extending from the remote station to the central station, a transmit set of repeaters serially connected in the transmit line at spaced positions, a receive set of repeaters serially connected at the receive line at spaced positions, means including a test signal generator for selectively generating predetermined limited number of test signals in the form of pulse trains including trios and duos and having respective frequency characteristics in a form directly usable for testing the repeaters in the transmit line, a fault line extending from the repeaters to the central station, a set of band pass filters respectively connected between the output sides of the repeaters and the fault line, the band pass filters being tailored to pass respective ones of the frequency characteristics to the fault line for detection at the central station, the number of repeaters in the transmit set exceeding the number of test signals so that at least two of the transmit repeaters are associated with band pass filters which are duplicatedly responsive to the same frequency characteristic, means in the central station for selectively applying an enabling signal to the fault line, and means including a switch associated with the duplicated band pass filters and responsive to the enabling signal for coupling a selected one of such duplicated filters to the fault line, a test signal encoding device at the central station coupled to the test signal generating means for encoding the test signals into a disguised form free of said frequency characteristics, and a test signal decoding device at the remote station for receiving the disguised test signals and reconverting them back into directly usable form including said trios and duos for application to the receive line for testing of the repeaters in the receive line.

Claim 21

In a communications system the combination comprising, a central station, a remotE station, a transmit line extending from the central station to the remote station, a receive line extending from the remote station to the central station, a transmit set of repeaters serially connected in the transmit line, a receive set of repeaters serially connected in the receive line, means including a test signal generator at the central station for generating test signals in directly usable form and for applying the test signals to the transmit line for testing of the transmit repeaters, the test signals being in the form of bipolar pulse trains having a plurality of pulse pattern types at least one of such pattern types containing bipolar violations, the pattern types alternating at rates which impart respective frequency characteristics to the test signal, a test signal encoding device at the central station interposable between the test signal generator and the transmit line for selectively converting the test signals into coded pulse trains having no bipolar violations, the encoding device including input means for converting the bipolar test signals to unipolar signals, detection means for detecting each of the plurality of pulse types and generating a transition signal in response to changes in the test signal between pattern types, gating means for combining the unipolar signal and the transition signal, clock means for retiming the combined signal, and output means for converting the retimed signal to true bipolar form free of bipolar violations, a test signal decoding device at the remote station interposed between the transmit line and the receive line, the decoding device including input means for converting the coded signals to a unipolar signal, a register for temporarily storing the unipolar signal, gating means for monitoring the condition of the register to detect coded transition signals and pulse patterns, outupt means responsive to the gating means for generating an output signal containing bipolar violations substantially corresponding to the test signal originally encoded, and coupling means responsive to receipt of the coded signal for coupling the output signal onto the receive line for separate testing of the repeaters in the receive line.

Claim 22

In a communications system the combination comprising, a central station, a remotE station, a transmit line extending from the central station to the remote station, a receive line extending from the remote station to the central station, a transmit set of repeaters serially connected in the transmit line, a receive set of repeaters serially connected in the receive line, means including a test signal generator at the central station for generating test signals in directly usable form and for applying the test signals to the transmit line for testing of the transmit repeaters, the test signals being in the form of bipolar pulse trains having a plurality of pulse pattern types at least one of such pattern types containing bipolar violations, the pattern types alternating at rates which impart respective frequency characteristics to the test signal, a test signal encoding device at the central station interposable between the test signal generator and the transmit line for selectively converting the test signals into coded pulse trains having no bipolar violations, the encoding device including input means for converting the bipolar test signals to unipolar signals, detection means for detecting each of the plurality of pulse types and generating a transition signal in response to changes in the test signal between pattern types, gating means for combining the unipolar signal and the transition signal, clock means for retiming the combined signal, and output means for converting the retimed signal to true bipolar form free of bipolar violations, a test signal decoding device at the remote station interposed between the transmit line and the receive line, the decoding device including input means for converting the coded signals to a unipolar signal, a register for temporarily storing the unipolar signal, gating means for monitoring the condition of the register to detect coded transition signals and pulse patterns, outupt means responsive to the gating means for generating an output signal containing bipolar violations substantially corresponding to the test signal originally encoded, and coupling means responsive to receipt of the coded signal for coupling the output signal onto the receive line for separate testing of the repeaters in the receive line.

Claim 23

The combination as claimed in claim 15 in which the pulse pattern types are positive trios having two positive pulses and one negative pulse, negative trios having two negative pulses and one positive pulse and bipolar patterns having one positive pulse and one negative pulse.

Claim 24

The combination as claimed in claim 15 in which a fault line extends from the repeaters to the central station and a set of band pass filters is respectively coupled between the output sides of the repeaters and the fault line, the band pass filters being tailored to pass respective ones of the frequency characteristics to the fault line for individual testing of the repeaters by the test signals.

Claim 25

The combination as claimed in claim 17 in which an additional set of transmit and receive repeaters are serially connected at spaced positions in the transmit and receive lines respectively and a corresponding set of band pass filters are connected to the same fault line, and means are provided including switches operated by a signal applied to the fault line at the central station for selectively actuating the sets of band pass filters for response to a test signal.