Network path test circuit

Claim 2

A test circuit for testing call connections established through a switch network of a switching system, said test circuit comprising means for applying a test tone signal simultaneously to both a transmit and receive path comprising one of the call connections, and means responsive to said tone applying means for detecting path reversals occurring in the call connections and for enabling the switching system to establish another call connection in accordance with a predetermined value of reflected impedance of the call connection denoting a transmit and receive path reversal.

Claim 3

The test circuit set forth in claim 1 wherein said applying means comprises means for generating the test tone signal, and means enabled by the switching system for momentarily coupling said tone signal generating means simultaneously to both the call connection transmit and receive paths.

Claim 4

The test circuit as set forth in claim 2 wherein said coupling means comprises hybrid means having an input circuit and a pair of output circuits for coupling tone signals appearing on the input circuit simultaneously to both output circuits, and relay means selectively operated by the switching system for connecting said tone signal generating means to the hybrid input circuit and each of the hybrid output circuits individually to the call connection transmit and receive paths.

Claim 5

The test circuit as set forth in claim 3 wherein said detecting and enabling means comprises means for measuring impedance reflected by the call connection transmit and receive paths at the input circuit of the hybrid, and means enabled by a predetermined value of the measured impedance for indicating to the switching system an occurrence of a wire transposition in the transmit path and the receive path of the call connection.

Claim 6

The test circuit as set forth in claim 4 wherein said detecting and enabling means further comprises means fir signaling the switching system to initiate the establishment of the other call connection through the switching network a predetermined interval of time after detecting the occurrence of the transmit and receive path wire transposition.

Claim 7

A test circuit for use in testing telephone call connections established through a switch network of a telephone switching office, said test circuit comprising means for generating a test tone signal, means for momentarily coupling said tone signal generating means simultaneously to both a transmit and receive path comprising one of the telephone call connections, means responsive to said tone signal generating means for measuring impedance reflected by the call connection transmit and receive paths into said coupling means, and means for enabling the telephone switching office to initiate establishment of another telephone call connection through the switch network when a predetermined value of the measured reflected impedance indicates a wire transposition in the call connection transmit and receive paths.

Claim 8

A test circuit for use in testing telephone call connections established through a switch network of a telephone switching office, said test circuit comprising means for generating a test tone signal, means for momentarily coupling said tone signal generating means simultaneously to both a transmit and receive path comprising one of the telephone call connections, means responsive to said tone signal generating means for measuring impedance reflected by the call connection transmit and receive paths into said coupling means, and means for enabling the telephone switching office to initiate establishment of another telephone call connection through the switch network when a predetermined value of the measured reflected impedance indicates a wire transposition in the call connection transmit and receive paths.

Claim 9

The test circuit set forth in claim 6 wherein said momentarily coupling means comprises a relay responsive to the telephone switching office, a hybrid having an input circuit and a pair of output circuits and arranged to couple a tone signal appearing on the input circuit simultaneously to both output circuits, and means comprising make contacts of said relay for connecting said tone signal generating means to the hybrid input circuit and each of the hybrid output circuits individually to the call connection transmit and receive paths.

Claim 10

The test circuit set forth in claim 7 wherein said measuring means comprises means connected to said tone signal generating means for generating a reference signal having a predetermined voltage level, and means including the hybrid input circuit and connected to said tone signal generating means by operation of said relay for generating a variable signal having values depending upon the reflected impedance appearing at the input circuit of said hybrid.

Claim 11

The test circuit set forth in claim 8 wherein said measuring means further comprises amplifying and rectifying means coupled to said reference and said variable signal generating means for generating a first output voltage signal from said reference signal and a second output voltage signal in response to said variable signal, and detector means coupled to said amplifying and rectifying means for generating a bias voltage output signal when said second output voltage signal is greater in magnitude than a predetermined value of said first output voltage signal and for inhibiting the generation of the bias voltage output signal when said second output voltage signal is less than the predetermined value of said first output voltage signal.

Claim 12

The test circuit set forth in claim 9 wherein said enabling means comprises control means coupled to said detector means and responsive to the bias voltage output signal thereof for signaling absence and presence of wire transpositions in the transmit and the receive path of the call connection to the telephone switching office in accordance with the value of the reflected impedance appearing at the input circuit of said hybrid.

Claim 13

A test circuit for use in testing a telephone call connection established through a switch network of a telephone switching office from a four-wire incoming trunk to a two-wire outgoing hybrid trunk, said test circuit comprising generator means for generating a test tone signal, hybrid means having an input circuit and a pair of output circuits for coupling a tone signal appearing on the input circuit simultaneously to both output circuits, relay means responsive to the telephone switching office and having contacts for momentarily connecting said generator means to the hybrid means input circuit and each of the hybrid means output circuits individually to a transmit path and a receive path of the four-wire incoming trunk, first path means connected across said generator means for generating a first tone signal having a predetermined voltage level, second path means including the hybrid means input circuit and connected across said generator means by operation of said contacts for generating second tone signals of voltage levels corresponding to values of impedance reflected back over the telephone call connection from the two-wire hybrid trunk through the switch network to the hybrid means input circuits, amplifying and rectifying means coupled to said first and said second path means for generating a first output voltage from said first tone signal and various values of a second output voltage in response to said second tone signals, detector means coupled to said amplifying and rectifying means for generating a bias voltage output signal when said second output voltage is greater in magnitude than a predetermined value of said first output voltage and for inhibiting the generation of the bias voltage output signal when said second output voltage is less in magnitude than the predetermined value of said first output voltage, and means coupled to said detector means and responsive to the bias voltage output signal thereof for signaling absence and presence of wire transpositions in the call connection transmit and receive paths to the telephone switching office and for enabling the telephone switching office to establish another call connection when the reflected impedance appearing at the hybrid means input circuit indicates a wire transposition in the call connection transmit and receive paths.

Claim 14

A test circuit for use in testing a telephone call connection established through a switch network of a telephone switching office from a four-wire incoming trunk to a two-wire outgoing hybrid trunk, said test circuit comprising generator means for generating a test tone signal, hybrid means having an input circuit and a pair of output circuits for coupling a tone signal appearing on the input circuit simultaneously to both output circuits, relay means responsive to the telephone switching office and having contacts for momentarily connecting said generator means to the hybrid means input circuit and each of the hybrid means output circuits individually to a transmit path and a receive path of the four-wire incoming trunk, first path means connected across said generator means for generating a first tone signal having a predetermined voltage level, second path means including the hybrid means input circuit and connected across said generator means by operation of said contacts for generating second tone signals of voltage levels corresponding to values of impedance reflected back over the telephone call connection from the two-wire hybrid trunk through the switch network to the hybrid means input circuits, amplifying and rectifying means coupled to said first and said second path means for generating a first output voltage from said first tone signal and various values of a second output voltage in response to said second tone signals, detector means coupled to said amplifying and rectifying means for generating a bias voltage output signal when said second output voltage is greater in magnitude than a predetermined value of said first output voltage and for inhibiting the generation of the bias voltage output signal when said second output voltage is less in magnitude than the predetermined value of said first output voltage, and means coupled to said detector means and responsive to the bias voltage output signal thereof for signaling absence and presence of wire transpositions in the call connection transmit and receive paths to the telephone switching office and for enabling the telephone switching office to establish another call connection when the reflected impedance appearing at the hybrid means input circuit indicates a wire transposition in the call connection transmit and receive paths.

Claim 15

A switch network path reversal test circuit for use in testing transmit and receive paths of a telephone connection established through a telephone switching office, said test circuit comprising a tone signal generator a hybrid having an input circuit and a pair of output circuits for coupling a tone signal appearing on the input circuit simultaneously to both output circuits, a relay responsive to the telephone switching office having make contacts for connecting said tone signal generator to the hybrid input circuit and each of the hybrid output circuits individually to the transmit and receive paths, and means coupled to said tone signal generator and said hybrid by operation of said relay for detecting presence of path reversals occurring in the transmit and receive paths of the telephone connection in accordance with the transmit and receive path inpedances reflected into the hybrid input circuit.

Claim 16

A switch network path reversal test circuit for use in testing transmit and receive paths of a telephone connection established through a telephone switching office, said test circuit comprising a tone signal generator a hybrid having an input circuit and a pair of output circuits for coupling a tone signal appearing on the input circuit simultaneously to both output circuits, a relay responsive to the telephone switching office having make contacts for connecting said tone signal generator to the hybrid input circuit and each of the hybrid output circuits individually to the transmit and receive paths, and means coupled to said tone signal generator and said hybrid by operation of said relay for detecting presence of path reversals occurring in the transmit and receive paths of the telephone connection in accordance with the transmit and receive path inpedances reflected into the hybrid input circuit.