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    EMBEDDED SERVO TRACK FOLLOWING SYSTEM AND METHOD FOR WRITING SERVO TRACKS
    22.
    发明专利
    EMBEDDED SERVO TRACK FOLLOWING SYSTEM AND METHOD FOR WRITING SERVO TRACKS 未知

    公开(公告)号：DE3275446D1

    公开(公告)日：1987-03-19

    申请号：DE3275446

    申请日：1982-11-30

    Applicant: NORTHERN TELECOM INC

    Inventor： OLIVER THEODORE A ,  NELSON DAVID L ,  CHAN KEAT-LYE

    IPC: G11B21/10 ,  G11B5/012 ,  G11B5/596 ,  G11B5/58

    Abstract: The system includes positioning means energizable for moving the read/write head to preselected recording positions relative to the disc and drive means for creating relative movement between the disc and the read/write head thereby enabling the transfer of data between the storage medium and the head. A plurality of servo tracks are embedded or recorded in servo data sectors on the disc for identifying preselected radial positions or informational data tracks on the disc. The servo data tracks are provided with a nonuniform radial track density. The track density of the servo tracks varies from more dense at the periphery of the disc to less dense at the interior of the disc. The radial track density of the servo data tracks is established with a method of writing embedded servo data that allows the unique performance characteristics of the moving read/write head to determine the actual spacing of the tracks. A clock track is written by writing a single pulse on a fixed clock track head, phase-lock looping to an intermediate clock track, which is written on a moving read/write head, and then phase-lock looping up to the final clock track which is written on the fixed clock track head. Radial track density is then determined by moving one of the read/write heads to a limit stop and writing a reference track.

    METHODS OF AND APPARATUS FOR DETERMINING ELECTRICAL CHARACTERISTICS OF TRANSMISSION LINES
    23.
    发明专利
    METHODS OF AND APPARATUS FOR DETERMINING ELECTRICAL CHARACTERISTICS OF TRANSMISSION LINES 未知

    公开(公告)号：CA1156721A

    公开(公告)日：1983-11-08

    申请号：CA357333

    申请日：1980-07-30

    Applicant: NORTHERN TELECOM INC

    Inventor： MORRIS DARRYL C ,  SAUCIER NORMAND A ,  PHILLIPS LOT

    IPC: G01R27/26 ,  G01R31/02 ,  H04M3/30 ,  G01R19/00 ,  G01R27/00

    Abstract: METHODS OF AND APPARATUS FOR DETERMINING ELECTRICAL CHARACTERISTICS OF TRANSMISSION LINES Apparatus is disclosed for automatically measuring accurately and rapidly alternating and direct voltages, resistance, and capacitance of a telephone line. Direct voltages and relatively high resistances can be determined by filtering out 60 Hz a.c. signals and measuring line current with and without a voltage source connected in series with the line. Capacitance is measured by charging the line from the voltage source, discharging the line into a plurality of integrators having different time constants, and sampling the output voltage of one of the integrators after a respective integral number of 60 Hz periods. The integrator whose output voltage is sampled depends on the capacitance being measured. The resultant measurement is corrected in respect of voltages on the line by performing a second integration without again charging the line, and the corrected result is modified to take into account the previously measured resistance of the line.

    METHOD AND APPARATUS FOR MOUNTING MAGNETIC TAPE HEADS
    24.
    发明专利
    METHOD AND APPARATUS FOR MOUNTING MAGNETIC TAPE HEADS 未知

    公开(公告)号：CA1153111A

    公开(公告)日：1983-08-30

    申请号：CA384477

    申请日：1981-08-24

    Applicant: NORTHERN TELECOM INC

    Inventor： SIMS DEWEY M JR

    IPC: G11B5/10 ,  G11B5/48

    Abstract: METHOD AND APPARATUS FOR MOUNTING MAGNETIC TAPE HEADS An arrangement for mounting magnetic tape heads in magnetic tape players, recorders, and other similar machines, comprises a mounting plate shaped for fixedly connecting a tape head therewith. A housing portion of the machine includes a base on which the mounting plate is pivotally supported for side-to-side, i.e., pivotal, movement, and housing sidewalls between which the side edges of the mounting plate are received. An adjustment mechanism is provided to selectively pivot the mounting plate into an aligned position, wherein the magnetic recording "gaps" of the tape head are in a substantially perpendicular relationship with the direction of motion of a magnetic tape sliding thereover. Channels are disposed along the mounting plate side edges and the adjacent housing sidewalls, and a solidifying plastic material is injected therein to form keys which positively retain the tape head in the aligned position.

    MODULAR SWITCH
    25.
    发明专利
    MODULAR SWITCH 未知

    公开(公告)号：CA1148596A

    公开(公告)日：1983-06-21

    申请号：CA371290

    申请日：1981-02-19

    Applicant: NORTHERN TELECOM INC

    Inventor： HASKINS STEVE W

    IPC: H01H23/00 ,  H01H21/80 ,  H01H21/18

    Abstract: MODULAR SWITCH A modulator switch, such as can be used for telecommunication purposes has a hollow body within which are a plurality of cantilever contact members, there being a center contact member and at least one side contact member. The center contact is biased towards one side or the other and has an extension actuated by an actuator rotatably mounted on the body. Actuation to make, break or transfer contact can be provided. The switch can be designed for sliding on a cover or another switch. The particular selection of two, or three contacts provides the particular actuation required.

    APPARATUS FOR CONVERTING AN A.C. INPUT SIGNAL TO A RECTIFIED AND SMOOTHED D.C. SIGNAL
    26.
    发明专利
    APPARATUS FOR CONVERTING AN A.C. INPUT SIGNAL TO A RECTIFIED AND SMOOTHED D.C. SIGNAL 未知

    公开(公告)号：CA1139838A

    公开(公告)日：1983-01-18

    申请号：CA357331

    申请日：1980-07-30

    Applicant: NORTHERN TELECOM INC

    Inventor： MORRIS DARRYL C

    IPC: G01R19/22 ,  H02M7/217 ,  H03K5/00 ,  H02M7/00

    Abstract: APPARATUS FOR CONVERTING AN A.C. INPUT SIGNAL TO A RECTIFIED AND SMOOTHED D.C. SIGNAL Offset voltages of a precision rectifier circuit, buffer amplifiers, and an input comparator of a log converter are compensated for by charging a coupling capacitor to the combined total offset voltage of the apparatus. The charging is effected by causing the comparator to operate as a unity gain inverting amplifier during part of the operating cycle of the log converter when the comparator output signal is not used, so that the log converter operation is not adversely affected. During such charging the input of the precision rectifier circuit, to which the a.c. input signal is normally applied, is grounded. Throughout the charging and associated switching operations a capacitor of a smoothing filter connected following the precision rectifier circuit is disconnected from ground to isolate the smoothing filter output from ground and to prevent switching transients from affecting the charge of this capacitor.

    28.
    发明专利
    未知

    公开(公告)号：FR2455795B1

    公开(公告)日：1982-12-10

    申请号：FR8009663

    申请日：1980-04-29

    Applicant: NORTHERN TELECOM INC

    IPC: H01T1/20 ,  H01T2/02 ,  H01J17/30 ,  H02H9/04

    Abstract: A gas filled surge arrester having improved impulse ratio, characterized by an ion source in an electric field outside of the spark gap.

    BASE FOR TELEPHONE SET, FOR ALTERNATIVE DESK AND WALL MOUNTING
    29.
    发明专利
    BASE FOR TELEPHONE SET, FOR ALTERNATIVE DESK AND WALL MOUNTING 未知

    公开(公告)号：CA1136786A

    公开(公告)日：1982-11-30

    申请号：CA357281

    申请日：1980-07-29

    Applicant: NORTHERN TELECOM INC

    Inventor： ADAMS WILLIAM J ,  WERNET WILLIAM F ,  HASKINS STEVE W

    IPC: H04M1/02 ,  H04M1/11

    Abstract: BASE FOR TELEPHONE SET, FOR ALTERNATIVE DESK AND WALL MOUNTING An adaptable telephone baseplate can be used for either wall mounting or desk or table top mounting. The baseplate has an enclosed recess at an intermediate position and a modular jack position at what would be the top edge when wall mounted. A slot connects the jack position and enclosed recess. When wall mounted a short cord can be inserted in the slot with a plug at one end being inserted in the jack at the jack position and a plug at the other end being in the recess for insertion into a wall jack. When desk mounted a normal line cord enters through a groove into the jack position for insertion of a plug into a jack. Alternatively a line cord can enter through the groove, extend along the slot and then pass up through the slot for hard wiring of the conductors to a circuitboard. Snap-in mountings are provided for the jack, a circuit board, ringer and possibly other items. For some telephones a battery housing can be provided while in others the battery housing can be omitted, by the alternative use of two inserts in the mold for the baseplate.

    30.
    发明专利
    未知

    公开(公告)号：IT8121709D0

    公开(公告)日：1981-05-14

    申请号：IT2170981

    申请日：1981-05-14

    Applicant: NORTHERN TELECOM INC

    Inventor： SIMS DEWEY M JR

    IPC: G11B15/675 ,  G11B

    Abstract: A cassette or cartridge-loading tape transport is disclosed, for use in magnetic recorders and the like, especially data recorders. The device includes tracks for slidably receiving a cassette or cartridge. A plate is slidably supported below the tracks and a drive motor is mounted on the plate. A constant-force spring biases the plate to a forward position. A plurality of lever arms supporting rollers are pivotally mounted adjacent the plate. Each lever arm includes a cam surface cooperating with a cam surface on the plate so that the rollers on the arms are moved from a lowered, inoperative position to a raised position engaging, locating and locking the cassette or cartridge within the recorder. A constant-force spring biases the lever arms to a raised position.

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