Abstract: Digital data recording/reproducing apparatus which uses a simple coding scheme for DC channel codes of the form M/N where M=N-1 and M and N are positive integers.

Abstract: A magnetic tape cassette recording/reproducing apparatus includes a magnetic tape cassette loader which allows easy insertion and removal of a cassette relative to the apparatus and which positively locks the cassette within the apparatus during recording and reproducing operations. The magnetic tape cassette loader includes a cassette holder that is tiltable and slidable relative to the recorder to permit easy insertion and removal of a cassette therein; a handle and latch assembly for handling and latching the cassette holder in the recorder; and an interlock mechanism for locking and unlocking the latch mechanism in response to actuation by a magnetic tape threading apparatus.

Abstract: In a helical scan recorder in which timing signals are recorded on adjacent slant tracks on magnetic tape, an automatic tracking technique for maintaining correct reproduce head to track positioning. The automatic tracking technique includes reproducing recorded timing signals from adjacent slant tracks on magnetic tape, producing first and second simultaneous repetitive reference signals which are coherent with the reproduced timing signals and which are 180.degree. out of phase with each other, simultaneously sampling each of the reference signals with the reproduced timing signals, selecting from the sampled reference signal the signals which are sampled in the mid-range of values thereof, and comparing the selected sampled reference signals and producing a tracking error signal if there is a difference therein.

Abstract: A magnetic tape cassette helical scan magnetic tape recorder has a magnetic tape threading and transport apparatus including multi-surface, multi-radius air bearing blocks for transporting magnetic tape in a helical path around a tilted rotary head scanner. Vacuum walls located on either side of the rotary head scanner assist in threading the magnetic tape from a magnetic tape cassette around the rotary head scanner. The air bearing blocks are moved into position contiguous to the rotary head scanner after the vacuum threading operation is completed. The vacuum walls have longitudinal slots which are substantially coextensive with the extent of the air bearing blocks. A vacuum sensor is positioned at the end of the slots away from the rotary head scanner so that the sensor is only actuated when the tape is against the whole length of the wall. This prevents damage to the tape when the air bearing blocks are moved behind the threaded tape.

Abstract: A tape keeper for use in magnetic tape recording and/or reproducing apparatus to keep tape on tape transport elements. The tape keeper has a plurality of flexible bristles supported on a support adjacent to a tape transport element. The element includes spaced tape edge guides between which the bristles extend to keep the tape on the element.

Abstract: In a helical scan magnetic tape recorder, a rotary magnetic head scanner includes odd and even azimuth data reproduce heads and odd and even azimuth sense heads on the head wheel to effect automatic tracking. The odd and even azimuth sense heads establish a tracking error signal when reproduced signal envelopes are not equal. The error signal is used to control a capstan servo to maintain correct data head-to-track positioning.

Abstract: A helical scan magnetic tape recorder includes a rotary scanner having magnetic heads which record and reproduce data on slant tracks of magnetic tape helically transported about the rotary scanner. Low frequency tones representing a time code or other digital information are recorded by the data heads of the rotary head scanner in the same lateral location such as preamble segments of the data tracks. The recorded time code is recovered by means of a stationary magnetic head. The recovered low frequency tones are converted into digital information such as a digital time code which provides tape location information for editing or searching purposes as well as other auxiliary information such as recorder serial number, data rate codes, etc.

Abstract: A magnetic tape recorder includes a rotary head scanner, a cartridge for containing a single reel of magnetic tape having a leader block at its end, a take-up reel and a leader block channel defining a tape path from the cartridge, past the rotary head scanner, to the take-up reel. A tape threading apparatus includes a first rotatably mounted arm segment, a first motor for rotating the first arm segment, a second arm segment rotatably mounted to the first arm segment, a second motor mounted on the first arm segment for rotating the second arm segment and a leader block carrier mounted on the end of the second arm segment for engaging the leader block to move it along the leader block channel.

Abstract: A helical scan magnetic tape recorder includes a rotary magnetic head scanner and a received magnetic tape cassette including spaced coplanar supply and take-up reels having magnetic tape spooled on the reels with a span of magnetic tape extending between the reels. Supply and take-up vacuum cavities are located contiguous to and on respective opposite sides of the scanner. Supply and take-up capstans are spaced from the rotary head scanner located in a tape transport path between the vacuum cavities and the tape cassette. Magnetic tape is initially removed from the cassette and moved to a tape vacuum loading position where it partially contacts the rotary head scanner, by a mechanical threading device. Thereafter, vacuum is applied to the vacuum cavities to draw the tape into contact with the vacuum cavities to substantially wrap the tape around the rotary head scanner. The supply and take-up capstans are rotated during vacuum threading to assist drawing the tape into the vacuum cavities.

Abstract: A helical scan magnetic tape recorder includes tape threading and guiding apparatus for threading magnetic tape from a two reel cassette about a rotary magnetic head scanner and for tensioning the tape during tape transport. The threading and guiding apparatus includes supply and take-up compliance elements which are mounted for movement between (1) cassette loading positions behind a tape span in a magnetic tape cassette; (2) tape vacuum loading positions in which the elements draw tape out of the cassette and partially contact it with the rotary head scanner; and (3) operating positions in which the elements draw tape around the respective supply and take-up capstans and tension the tape during tape transport past the rotary head scanner.

Abstract: A digital data synchronizer, synchronizes a digital data system to an incoming serial bit stream having a segment of pseudo random bit sequence, which is a function of a predetermined primitive polynomial, preceeding the start of data. The synchronizer includes a first feedback shift register configured as a multiplier for generating the pseudo random bit sequence. The multiplier register operates on the incoming serial bit stream to determine whether a valid bit sequence of the primitive polynomial is present in the incoming serial bit stream, and if it is, a zero output is produced. A second feedback shift register configured as a divider produces a pseudo random bit sequence which is also a function of the predetermined primitive polynomial. A counter is provided to monitor the number of zeros outputted by the multiplier feedback shift register.

Abstract: Disclosed is a reel hub latch assembly used in magnetic tape recording/reproducing apparatus. The disclosed reel latch assembly accurately locates a reel on a hub and prevents slippage between the hub and reel when the reel is rotated to transport tape onto and off of the reel. The reel mounting hub has an annular groove containing an annular, U-shaped radial spring at the bottom of the groove. The radial spring has a plurality of circumferentially spaced fingers. An annular garter spring is located in the groove overlying the circumferentially spaced fingers of the radial spring. A magnetic tape reel, mounted on the hub, has a conical inner wall which is engaged by the garter spring. Preferably, the engaging portions of the spring are shaped to conform to the shape of the conical wall to reduce stresses on the reel.

Abstract: A magnetic tape cassette transport/accessor assembly is actuated by a sprocket driven, belt drive system. First and second belt drives drive the transport/accessor assembly in horizontal and vertical directions and are tensioned by spring dampener assemblies. Each spring dampener assembly dampens rough and jerky movements and effects smooth and gentle acceleration and deceleration of the transport/accessor assembly. Each spring dampener assembly also provides compensation for belt drive wear, belt stretching and differential thermal expansion and contraction of the belt.

Abstract: A helical scan magnetic tape record/reproduce apparatus includes apparatus for changing the helix angle of magnetic tape relative to a rotary head scanner. A pair of elongate, arcuate air-bearing guides are disposed immediately adjacent and tangential to opposite sides of a circumferential surface of the rotary head scanner. The guides are at a first elevation and first angle and a second elevation and second angle, respectively, to cooperatively guide magnetic tape along a path at a predetermined helix angle while the magnetic tape is partially wrapped around the rotary head scanner. The planes of the air-bearing guides are changed in equal but opposite directions to change the helix angle of the tape relative to the rotary head scanner.

Abstract: In a magnetic tape recording/reproducing apparatus, magnetic tape is transported between supply and take-up reels which include reel brake assemblies which are simple, reliable and compact. The brake assembly includes a linear stepper motor and a brake pad mounted on a linearly actuated shaft of the stepper motor. Each reel is mounted on a hub driven by a belt and pulley arrangement. Each reel brake assembly is mounted adjacent the pulley with the motor shaft extending radially relative to the pulley. Upon actuation of the linear stepper motor, the motor shaft is moved radially to engage the brake pad with the pulley. In a preferred embodiment, the magnetic tape recording/reproducing apparatus includes coaxial reels which are driven by coaxially mounted pulleys having individual brake assemblies.

Abstract: A web, contained in a cassette, is automatically threaded along an external transport path past a web utilization station, by means of a flexible threading band which pushes the web around the path. In a preferred embodiment, magnetic tape, contained in a cassette, is automatically threaded about a tape transport path past a magnetic head assembly by means of a flexible threading band contained in a threading band. The threading band is positioned behind a segment of the magnetic tape and is ejected from its own cassette, (1) to pull the magnetic tape out of the tape cassette, (2) to wrap the tape around a rotary head scanner of a magnetic tape recording/reproducing apparatus, and (3) to configure the tape to the tape transport path. After the tape is threaded, the flexible band is withdrawn into its cassette.

Abstract: Disclosed is a magnetic tape cassette handling apparatus which is compact and reliable and which handles cassettes gently and firmly. The handling apparatus includes (a) a pusher member for gently moving a cassette forwardly into a cassette receiving location, and (b) clamping members for firmly clamping a cassette while moving the cassette rearwardly out of the cassette receiving location. The cassette handling apparatus is preferably located in a central opening of a cassette storage ferris wheel structure which is mounted adjacent to a magnetic tape recorder/player. Thus, the cassette handling apparatus loads and unloads a cassette from the ferris wheel structure into and out of the magnetic tape recorder/player.

Abstract: The rotary head scanner of a helical scan magnetic tape recording/reproducing apparatus includes a carrier which supports the fixed drum or drums of the scanner by means of full radius contact between the drum and the carrier. A rotary head scanner includes upper and lower stationary drums and a head wheel rotably mounted in a slot between the stationary drums. The head wheel includes one or more magnetic heads mounted on the periphery of the head wheel. The rotating heads record on and reproduce from slant tracks on magnetic tape guided around the scanner in a helical path. The upper and lower drums are supported by a carrier which effects full radius contact over a large circumferential arc. Such contact effects rigid mounting of the drums without distortion, thus, minimizing distortion in magnetic tape as it is guided around the rotary head scanner.

Abstract: A magnetic tape cassette transport/accessor assembly for use in a system including magnetic tape cassette storage and magnetic tape cassette record/reproduce apparatus. The cassette transport/accessor assembly transports cassettes between locations in the system in a gentle and reliable manner. The magnetic tape cassette transport/accessor assembly includes upper and lower carriages having spring-biased, V-grooved wheels, which travel on spaced, parallel, upper and lower V-shaped horizontal rails located at the top and bottom of the cassette storage and record/reproduce apparatus. An accessor platform travels on two vertical rails rigidly mounted on the upper and lower carriages. The accessor platform supports two accessor assemblies which travel laterally on lead screws to effect insertion and extraction of magnetic tape cassettes. The transport/accessor assembly is lightweight since no actuating motors or motor supports are mounted on it.

Abstract: In a magnetic tape cassette storage and magnetic tape cassette record/reproduce system, disclosed is an accessor which inserts or extracts a cassette from a storage location or a record/reproduce device. The accessor includes a cassette gripper assembly which handles different sizes of cassettes. Lateral motion of the accessor (a) actuates the gripper assembly to grip and ungrip a cassette and (b) effects locking and unlocking of the gripper assembly. A pair of accessors are mounted on an accessor platform so that one accessor can insert a cassette while the other accessor extracts a cassette, either at the same location (record/reproduce device) or at different locations (storage compartments).