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9 records (took 0.024 seconds)

    1.
    发明专利
    未知

    公开(公告)号：BR7903166A

    公开(公告)日：1980-01-15

    申请号：BR7903166

    申请日：1979-05-21

    Applicant: CSELT CENTRO STUDI LAB TELECOM

    Inventor： MELINDO F

    IPC: H04Q3/72 ,  H04M19/00 ,  H04Q1/28 ,  H04Q1/30 ,  H04Q3/52

    Abstract: The two talking wires of a line loop extending from a subscriber station to a central office, provided with respective blocking capacitors, are connected on the subscriber side of these blocking capacitors to respective signal detectors fed from a common battery and cross-coupled by a common compensating capacitor. The two signal detectors receive outgoing signals from the central-office equipment via a common photoelectric coupler and transmit incoming signals to that equipment by way of respective bistable threshold comparators and individal photoelectric couplers. The two signal detectors with their threshold comparators are constituted in integrated circuity by mutually complementary transistors and diodes together with associated resistors.

    2.
    发明专利
    未知

    公开(公告)号：DK63281A

    公开(公告)日：1981-08-20

    申请号：DK63281

    申请日：1981-02-13

    Applicant: CSELT CENTRO STUDI LAB TELECOM

    Inventor： MELINDO F

    IPC: H04M3/02 ,  H04M19/02 ,  H04M

    Abstract: A circuit arrangement for emitting ringing signals to a subscriber station in response to a call signal electronically generated at a telephone exchange comprises a control unit which, in the presence of such call signal, intermittently reverses a switching relay normally connecting the talking conductors of the subscriber line to monitoring equipment of the exchange whereby these conductors periodically receive a high-voltage ringing current, e.g. of 25 Hz, from a local oscillator in series with a d-c supply. The direct current is blocked by a line-terminating capacitor until the called subscriber lifts the receiver off the hook to close the line loop. If this occurs while the line is connected to the oscillator, a sensor in the control unit detects a significant disparity between the durations of the positive and negative voltage swings in an oscillator cycle and causes the release of the switching relay when that disparity exceeds a dynamic threshold determined by the actual cycle length.

    3.
    发明专利
    未知

    公开(公告)号：BR8100796A

    公开(公告)日：1981-08-25

    申请号：BR8100796

    申请日：1981-02-09

    Applicant: CSELT CENTRO STUDI LAB TELECOM

    Inventor： MELINDO F

    IPC: H04M3/02 ,  H04M19/02

    Abstract: A circuit arrangement for emitting ringing signals to a subscriber station in response to a call signal electronically generated at a telephone exchange comprises a control unit which, in the presence of such call signal, intermittently reverses a switching relay normally connecting the talking conductors of the subscriber line to monitoring equipment of the exchange whereby these conductors periodically receive a high-voltage ringing current, e.g. of 25 Hz, from a local oscillator in series with a d-c supply. The direct current is blocked by a line-terminating capacitor until the called subscriber lifts the receiver off the hook to close the line loop. If this occurs while the line is connected to the oscillator, a sensor in the control unit detects a significant disparity between the durations of the positive and negative voltage swings in an oscillator cycle and causes the release of the switching relay when that disparity exceeds a dynamic threshold determined by the actual cycle length.

    6.
    发明专利
    未知

    公开(公告)号：SE7904735L

    公开(公告)日：1979-12-03

    申请号：SE7904735

    申请日：1979-05-30

    Applicant: CSELT CENTRO STUDI LAB TELECOM

    Inventor： MELINDO F

    IPC: H04Q3/72 ,  H04M19/00 ,  H04Q1/30

    Abstract: The two talking wires of a line loop extending from a subscriber station to a central office, provided with respective blocking capacitors, are connected on the subscriber side of these blocking capacitors to respective signal detectors fed from a common battery and cross-coupled by a common compensating capacitor. The two signal detectors receive outgoing signals from the central-office equipment via a common photoelectric coupler and transmit incoming signals to that equipment by way of respective bistable threshold comparators and individal photoelectric couplers. The two signal detectors with their threshold comparators are constituted in integrated circuity by mutually complementary transistors and diodes together with associated resistors.

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