Abstract: A novel circuit arrangement decodes Miller-squared (M.sup.2) encoded signals using Class II partial response (PR2) equalization techniques. The circuit arrangement utilizes a maximum-likelihood sequence estimator (detector) implemented by the Viterbi algorithm to minimize the probability of bit errors in a digital storage or transmission channel that employs M.sup.2 encoding in combination with PR2 equalization. The PR2 equalization channel is preferably modeled by a finite impulse response (FIR) filter which, in turn, is modeled by a finite-state trellis diagram. This allows creation of a modified trellis when M.sup.2 encoding is applied to the PR2 channel with the modified trellis providing the basis for implementing the detector according to the invention.

Abstract: A helical type tape recording and reproducing system records blocks of user data-of predetermined size by reformatting the user data blocks into physical blocks that are recorded on tape. The system format includes helical tracks in which user data blocks are recorded and longitudinal tracks for storing address information relating to the physical layout of the tape and to the content of the recording in the helical area. The system includes a partition access bookkeeping feature that stores information relating to locations at which searching or recording has been performed during a current load of a tape in the system, which is useful in accomplishing efficient searching for user data recorded on the tape. The present invention is directed to system search capabilities, including longitudinal searching along the tape and searching in the helical recording area of the tape.

Abstract: A magnetic transducer for reproducing/recording high frequency signals with a magnetic tape medium includes a pair of opposed transducer head halves separated by an insulation gap and bonded together to form a Y-shaped pole structure, each half including a laminated at least partially ferromagnetic core portion bounded on opposite surfaces with outer and inner conductive layers, each of which forms a winding coil portion. Each core section has a leg portion and an angularly disposed arm portion, the distal end of which is capped with a block-shaped ferromagnetic pole tip in magnetic path relation therewith, the two pole tips lying in a common plane transverse to the plane of the gap. The conductive layers, when conductively interconnected, such as by jumpers, form a one or two turn coil for the transducer.

Abstract: An apparatus for an axially displaced flexural bearing support assembly including a unitary or monolithic bearing support base member having a bearing receiving tube supported by a first and second generally parallel arrangement of flexural spoke members to control bearing pre-load due to axial differential expansion while eliminating radial displacement of the spindle or shaft supported within the tube. The spoke members of each arrangement include a plurality of spoke members arranged in parallel planes generally perpendicular to the axis of a spindle insertable within and supported within the tube by means of bearings. In the preferred embodiment, there are three spokes for each set in each plane, with the spokes being equiangularly displaced.

Abstract: Input data symbols are written in a write buffer then to a sync adder, which appends a pseudo randomly (PN) generated sync bit to the MSB position of a four-symbol sync word data field, to generate a sync word. Sync words may or may not be randomized and sent to a receiver whereafter synchronization is recovered and perhaps de-randomized symbols are written into particular positions of an ECC block in a read buffer which are derivable from the PN sequence. The ECC block is a data array having multi-bit sync words making up its rows and the bit positions of the sync words making up its columns. Synchronization recovery apparatus conceptually looks at each bit position across a row and in a top-to-bottom direction down each of the columns to locate that column which contains the appended PN sequence. Sync recovery involves the receiver re-generating the same PN sequence that was generated at the transmitter.

Abstract: A method and apparatus for input data clock presence detection which utilizes an up/down counter clocked by a reference clock, which operates at a nominal frequency rate half of the nominal rate of the input data clock, and an R/S flip-flop causing the up/down counter to count up when set, and to count down when reset. The R/S flip-flop is cleared by the reference clock and set by the input data clock. The counter is selected to count up to its maximum number and remain there when continuously clocked up. Similarly, when continuously clocked down, the counter reaches its minimum number (zero) and remains there. So long as the input data clock is present and has the correct rate, after each reference clock pulse resets the flip-flop and prepares the counter to count down, there is at least one input data clock that sets the flip-flop and prepares the counter to count up.

Abstract: A helical tape recording and reproducing system which has longitudinal physical address track for recording physical address data relating to the physical layout of the tape and a logical address track that contains data relating to the content of the recorded helical tracks. Each address track has recorded segments with each of said segments containing data corresponding to a particular pair of helical tracks recorded in said helical recording area. Each segment has a multiple bit front field of a first predetermined timing synchronization bit pattern, a first predefined synchronizing word, a multiple bit segment information field of data, a second predefined synchronizing word and a multiple bit rear field of a second predetermined timing synchronization bit pattern.

Abstract: A recording and reproducing system records blocks of user data of predetermined size by reformatting the user data blocks into physical blocks that are recorded on tape. Each physical block is recorded as a double frame on a set of successive helical tracks, preferably 32 tracks. The system has the capability of verifying whether a physical block has been accurately recorded, and if not, the system automatically rewrites the physical block downstream without stopping or repositioning the tape. If an accuracy verification confirmation does not occur until a next physical block is being recorded, the system demarks or invalidates that physical block being written, and rewrites both the failed physical block and that following physical block downstream of that physical block being written.

Abstract: An audio receiver FIFO memory buffer in the serial digital video interface allows improved timing synchronization between video and audio information. Furthermore, it eliminates unpleasant sound effects when multiple data samples are skipped or repeated in series. This FIFO receiver buffer receives data at an input write-data rate filling up the memory storage cells therein. An output read-data signal clocks the data out of the memory storage cells. The FIFO's fullness is monitored and maintained, in response to an external signal, to within a specified range delimited by an upper and a lower threshold. If the FIFO buffer fullness is below the range's lower threshold, then the FIFO's read address pointer is held so that the immediately preceding read out data element is read out again, but only once. On the other hand, the FIFO buffer fullness is over the range's upper limit, then the FIFO's write address pointer is held so that the immediately preceding written in data element is written over, but only once.

Abstract: A tape recording and reproducing system records blocks of user data of predetermined size by reformatting the user data blocks into physical blocks that are recorded on tape. Each physical block is recorded as a double frame on a set of successive helical tracks, preferably 32 tracks. The system has the capability of verifying whether a physical block has been accurately recorded, and if not, the system rewrites the physical block downstream without stopping or repositioning the tape. If an accuracy verification confirmation does not occur until a next physical block is being recorded, the system demarks or invalidates that physical block being written, and rewrites both the failed physical block and that following physical block downstream of that physical block being written.

Abstract: A switcher mixer architecture creates special effects such as a dissolve or a wipe from one priority structure of the elements of an image scene to a completely different prioritized ordering of those same or even other elements that comprise the same or a different image scene. The special effect can be thought of as a "priority transition" in the sense that the priority of a set of input image signals can be transitioned from that of a "from" image to that of a "to" image. The switcher mixer architecture eliminates a soft border artifact from the special effect by allowing a border to be given its own priority as though the border were a separate image input as well as to couple together (1) a source, or "from," image having one or more elements; (2) a destination, or "to," image having one or more elements, which could be the same or different than the "from" image elements; and (3) a border image for separating the source image and the destination image in an image display.

Abstract: In a data compression process such as employed to compress video or other data, it is preferable not to compress the image data representative of the video image in a sequential format, or to take the data from the same area of the image. To equalize the information content of the data prior to compression, the present shuffling/deshuffling technique divides the video image into a multitude of image representing blocks, and selects a predetermined number of the image blocks from different spatial locations in the image, to form a succession of data sets representative of the video image information. That is, the selection of the image representing blocks is such that the information content (complexity) in each data set is similar to the information content in each other data set and further similar to the average information content of the entire video image.

Abstract: An arrangement involving apparatus and process damps vibrations, for example, rotary or linear vibrations, in a member to be damped, for example, in a supply tension arm forming part of a tape transport of a digital cassette recording system. The arrangement includes a limited angle torquer motor having an output connected to the member such that the presence of the detected vibrations to be damped imparts corresponding vibrations to the shaft (output) of the motor which, in turn, results in a corresponding back EMF voltage within the motor. A servo circuit connected to the input of the motor is designed to be responsive to the back EMF voltage within the motor, actually to an emulated version of the back EMF voltage, for driving the motor in a way to thereby damp the vibrations within the motor shaft which, in turn, damps the rotary or linear vibrations within the member itself. Approximately 20dBs of attenuation in vibration at the resonant frequency has been shown.

Abstract: A method for analyzing the relative spatial alignment of the erase head pole tips relative to the record head pole tips on a recording of a magnetic tape to be partially overwritten by providing, through first and second erase heads, successive momentary erase pulses of a predetermined time duration in a predetermined phase relation on a non-overlapping basis, wherein each erase head thereby erases recorded information while leaving portions of information therebetween on adjacent track pairs, and then reading or playing back the results of the erasure for analysis of the RF envelope of the erasing pattern by a waveform monitor or ferrofluidic techniques. The duration of the erasures and playback is such that the RF envelope includes at least one erasure from the first erase head and at least one erasure from the second erase head.

Abstract: A magnetic transducer for reproducing/recording high frequency signals with a magnetic tape medium includes a pair of opposed transducer head halves separated by an insulation gap and bonded together to form a Y-shaped pole structure, each half including a laminated at least partially ferromagnetic core portion bounded on opposite surfaces with conductive layers, each of which forms a winding coil portion. Each core section is formed as one-half of a Y-shaped cross-sectional configuration having a leg portion and an angularly disposed arm portion, the distal end of which is capped with a block-shaped ferromagnetic pole tip in magnetic path relation therewith, the two pole tips lying in a common plane transverse to the plane of the gap. The conductive layers on the outer and inner surfaces of the laminated core section form outer and inner conductors which, when conductively interconnected, such as by jumpers, are configured to form a one or two turn coil for the transducer.

Abstract: A feedforward circuit applies a capstan drive current, or its equivalent, to the reel tension servo circuits whose associated reels are transporting the tape. The additional drive current to the reel drive motors increases the rotational velocity of the reels to maintain the same resultant acceleration between the tape driven by the capstan and the tape being transported between reels. Since the tape pack affects the gain of the feedforward circuit, a preselected average gain corresponding to the mean tape pack diameter is used to match different cassette sizes. A microprocessor may be used to provide the various signals and may vary the gain of the feedforward circuit not only in response to reel size but also in response to instantaneous reel tape pack diameter.

Abstract: The data unpacker receives packed parallel input data words having a fixed width of m bits, and it outputs parallel data words having a variable width of n bits. An input register stores the received words and applies them to a bit shifter. The bit shifter shifts the received data by a number of bit positions indicated by a shift control signal, and the shifted data is output therefrom as a parallel output word having n valid bits. The number n for each output word is received by the unpacker as a binary number. When n.gtoreq.m, a most significant (MSB) bit portion of that number is applied as first MSB control signal. The least significant bit (LSB) portion of n is applied to an adder which adds subsequently received LSB portions to provide a running sum. When the running sum is equal to or greater than m, the adder provides a second MSB control signal, corresponding to the most significant bit of the running sum.

Abstract: Deteriorated or aged magnetic recording media exhibiting undesirable properties such as shed, stickiness or squeal are restored to playable condition having no such objectionable properties by heating the media to an elevated temperature and for lengths of time sufficient to restore the media. A typical temperature used is 54.degree. C. and a typical effective time is 16 hours. Ambient humidity is suitable. The restored media can be used to transfer data or information to new media. Restored media can also be again heat treated for restoration purposes, if it deteriorates again.

Abstract: Error concealment of an erroneous pixel in a line of pixels is provided by adaptively using a large number of adjacent correct pixels along the same horizontal line. The invention discards any corrupted adjacent pixel which would be used in the calculation for a replacement pixel value, while modifying the weighting of the remaining adjacent correct pixels in accordance with the error pattern generated by the corrupted pixel or pixels. An overflow detection circuit also is included, which provides an acceptable replacement pixel value rather than using the unacceptable overflow value.