Abstract: A preferred embodiment of an electromagnetically controlled scanning magnetic transducer is described having two confronting core poles defining a physical transducing gap therebetween. A control winding is associated with each core pole. A control current applied to each control winding selectively saturates a portion of each core pole facing a record medium. Each saturated face portion defines an adjacent unsaturated highly permeable face portion. The highly permeable face portions of each core pole overlap across the gap to define a transducing zone. The information signal and control windings are arranged relative to one another to obtain information signal and control flux paths extending perpendicular to one another.

Abstract: An apparatus and method are provided for controlling the level of an audio output signal which has been recorded and is played back from a magnetic tape at a low or zero tape speed, such as utilized in jog mode or variable speed playback during editing. A gain control signal is provided to eliminate a disturbing repetitive audio signal which accompanies stop motion playback and to reduce that signal level at low tape speed playback. The gain control signal is made dependent on the magnitude of tape speed, and it is applied to adjust the audio output gain of the playback channel.

Abstract: An electromagnetically controlled scanning magnetic transducer has two magnetic core portions with confronting poles defining a transducing gap. A control winding is arranged in each core portion to provide a control flux therein. The control flux saturates a region of the transducer face of each core portion, adjacent to the gap. The saturated regions define adjacent unsaturated highly permeable regions which overlap at the gap to obtain a transducing zone. The transducing zone can be altered, moved, scanned or otherwise positioned along the transducer width by electromagnetically controlling the location and size of the saturated face regions.

Abstract: The decision feedback decoder of the invention receives sequentially sampled values of a signal waveform corresponding to data bits transmitted by a channel. A magnitude comparator compares the sampled values to a threshold and based on each comparison it provides subsequent decisions determining the values of the corresponding data bits. A predetermined number of previous decisions are stored and applied to a first and a second threshold adjustment circuit. Each circuit adjusts the threshold depending on the respective values of the previous decisions, while the first circuit provides the adjustment based on an assumption that the next decision to be made will have a first signal value and the second circuit provides the adjustment based on an assumption that the next decision will have a second signal value. When that next decision becomes available, it is utilized to select the correct adjusted threshold value for the next comparison by the magnitude comparator.

Abstract: In a head displacement measuring apparatus, a folded optical path is used to introduce a collimated beam of light from a light source to a split photo detector, wherein both the light source and the split photo detector are mounted external of the support housing which secures and supports the flexible head assembly. A pair of optical prisms direct the light beam parallel to a head supporting blade integral with the head assembly. A Fresnel lens secured to the blade, preferably at the head end, varies the position of the path of the light beam in response to lateral displacement of the blade and head, to likewise vary the extent that the beam impinges one or the other of the photo detectors. The difference of the signals from the split photo detector provides a precise measurement of the transverse displacement of the head from a nominal centered position.

Abstract: Structures of magnetic heads having superconducting shields are disclosed for spatially directing magnetic recording/playback fields. One embodiment is a thin film magnetic head with a layer of superconductor material associated with its throat. Further embodiments provide intertrack shielding and concentration of recording/playback fields into relatively small pole tip regions.

Abstract: A thin film magnetic array memory affords relatively high packing densities while avoiding the problem of magnetic domain creep through the use of thin films of superconducting material disposed on the work lines of the memory. The superconducting films shunt magnetic fields generated by currents carried within the word lines and prevent these fields from adversely affecting adjacent memory cells in the array. By constraining the magnetic fields with the use of the superconducting films, the word lines can be packed close to one another in the array structure, thereby increasing the amount of information that can be stored in a unit area of the array.

Abstract: A magnetic transducer and manufacturing method, where a transducer core is made from a composite block of magnetic material. The composite block has a first portion made of a first magnetic material, and a second portion made of a second magnetic material, the two block portions being integrally joined at corresponding planar surfaces. In the preferred embodiment, the first magnetic material is selected to have high granular density and other physical and magnetic properties which are necessary to obtain excellent transducing gap definition. The second magnetic material is selected to obtain high transducer performance. The composite block is machined around a periphery thereof at surfaces extending at oblique angles to said joined surfaces to provide a magnetic core having its first portion reduced to a wedge shaped portion.

Abstract: An ultra small track width magnetic transducer and manufacturing method. The transducer has two coplanar confronting magnetic poles provided by a thin film layer of magnetic material. The thickness of the layer defines a track width. A transducing gap is etched in the magnetic layer by utilizing focused ion beam milling technology. The thusly obtained gap has a predetermined length and depth and it separates the magnetic layer into two confronting coplaner magnetic poles. A layer of non-magnetic material is deposited over the magnetic layer to fill the transducing gap. The transducing gap may be etched in a plane extending orthogonally to the plane of the magnetic core layer. Alternatively, the transducing gap plane may extend at an oblique angle to the magnetic core layer to obtain a transducing gap useful in aszimuth recording/playback.

Abstract: Apparatus and methods for encoding information of one class into the parity for main data of another class. One such method and apparatus fundamentally takes one member A.sub.x of a limited first class of data called attribute data and concatenates it with main data. Parity is then calculated on the concatenate word. After the main data and parity is transmitted or recorded, the selected member of the first class of data may be recovered by comparing the received parity to the parity P" generated on the receiver side using the main data and each member of the first class of data to generate a plurality of syndromes. The first all zero syndrome identifies the member of the first class which was encoded into the parity of the main data. Another method and apparatus are similar except that the transmitter side calculates parity P.sub.ax for the selected member of the first class and then encodes that parity into the parity calculated for the main data.

Abstract: A magnetic transducer and manufacturing method are described, where a transducer core is made from a composite block of magnetic material. The composite block has a first portion made of a first magnetic material, and a second portion made of a second magnetic material, the two block portions being integrally joined at corresponding planar surfaces. In the preferred embodiment, the first magnetic material is selected to have high granular density and other physical and magnetic properties which are necessary to obtain excellent transducing gap definition. The second magnetic material is selected to obtain high transducer performance. The composite block is machined around a periphery thereof at surfaces extending at oblique angles to said joined surfaces to provide a magnetic core having its first portion reduced to a wedge shaped portion.

Abstract: The decision feedback decoder of the invention receives sequentially digital values corresponding to a data stream transmitted by a signal transmission channel. The decoder has two parallel signal paths. The first path has a first logic circuit which receives every other digital value corresponding to every other data bit of the transmitted data stream, and it provides and outputs subsequent decisions determining the values of these corresponding bits. The second path has a second logic circuit which receives sequentially all the digital values corresponding to all the data bits of the stream. During the time of providing each decision by the first logic circuit, the second logic circuit provides two subsequent decisions determining the respective values of two subsequent bits, but it outputs only every other decision, which alternates with the decisions provided by the first logic circuit.

Abstract: The data packer receives n-bit wide parallel data words, and it outputs m-bit wide packed parallel data words, where n is a variable and may change during the operation, and m is a fixed integer. The input data words are applied to a bit shifter and therefrom to a data output circuit where they are stored until the necessary m bits are obtained. In the preferred embodiment a control circuit which comprises an adder, receives information indicating the number of valid data bits in each input word, and it provides a running sum of the number of received valid data bits. When the number of bits in an input word is equal to or greater than m, the control circuit provides a first control signal which occurs simultaneously with an m-bit wide packed parallel output word provided by the output circuit. Any number of input bits which is less than m is added to a remainder of a previous sum which is also less than m.

Abstract: A storage container is of a configuration and dimensioned to retain either two DAT cassettes, two storage cases or one cassette together with one storage case. The size of the DAT cassette storage container is comparable in size and shape to a Beta video cassette storage case. The storage container has an interior structure that forms a pair of seats, each having two distinct parts. A first of the two parts is of a configuration for receiving and retaining the protective storage case for DAT cassettes. A second of the two parts is of a configuration for receiving the DAT cassette itself and retaining it within the container. The storage case and cassette are retained within the container with their length dimensions orthogonal.

Abstract: A method and apparatus detects synchronizing sequences in a digital data stream. The apparatus comprises a plurality of candidate sequence generators and associated vote counters which are used in conjunction with comparators to test the order of received synchronizing symbols of a predefined sequence of predefined symbols against a plurality of corresponding candidate symbols of candidate sequences. A candidate generators begins a new candidate sequence when an ambiguity in the input symbol sequence is detected, i.e., when a received symbol does not match a candidate symbol of one of the previous candidate sequences. The apparatus includes a voter decision logic circuit which selects a winner among the candidates based upon the number of votes or matches tallied for each candidate sequence.

Abstract: Plural magnetic transducing heads are employed to record and reproduce video information that is stored in a segmented format. One head is in contact with the magnetic recording tape while the other head is out of contact with it. The position of the head which is in contact with the tape is controlled by a suitable ramp voltage generated in accordance with the ratio of actual tape speed to normal play speed, to maintain the head generally aligned with a track on the tape. The other head, which is out of contact with the tape, is also positioned in the same fashion. When a repositioning of the heads is required, a determination is made whether the track of information being reproduced by the head in contact with the tape relates to a particular segment of a field, for example the last field.

Abstract: High speed digital data correlator utilizing as a summing circuit single bit full adder cells in a synchronous pipelined array arrangement to sum the number of bit matches with a selected correlation word in a serial data stream. Each adder cell has up to three inputs and provides a partial sum by adding up to three bits of equal powers of two. The simple full adder cell architecture minimizes interconnect lengths between the adjacent synchronous stages of the summing circuit and maintains near constant circuit density across the stages. These features contribute to an optimization of the operational speed of the correlator for any given circuit technology. The correlator of the preferred embodiment detects two complementary, mutually exclusive correlation words, using the same correlation circuit.

Abstract: An adjustable frequency signal generator is described which utilizes a stable fixed frequency oscillator in combination with an adjustable modulus frequency divider, to obtain a frequency divided output signal whose frequency may vary within a wide range, while maintaining spectral purity of a signal generated by the stable oscillator. In the preferred embodiment the modulus of the frequency divider is controlled by an up/down counter. The frequency of the frequency divided output signal is detected with respect to a reference signal frequency. When the detected output signal frequency is higher, the counter is incremented, thereby incrementing the modulus of the divider and decreasing the frequency of the output signal. Similarly, when the detected output signal frequency is lower than the reference signal frequency, the counter is decremented, whereby the modulus of the divider decreases and the output signal frequency increases.

Abstract: A soft clipping circuit particularly suited for use with audio signals avoids the need to use non-linear diode characteristics to determine the amount of clipping that is provided. A diode switching circuit which includes constant current sources is used to determine the output voltage of an amplifier at which clipping is to begin. Once this voltage is reached, the switching circuit disconnects the amplifier from a signal output terminal. At this time, the signal at the output terminal is determined solely by the values of resistors in a resistive dividing network connected between a signal input terminal and the output terminal.

Abstract: Data is received at a variable input rate and recorded on a longitudinal medium in the form of fixed length data blocks with variable length spacing between the blocks, utilizing a transducer mounted on a rotating scanner drum. The input data rate may change between various recording/playback operations by a ratio of 1:100 or more, but during a particular operation it remains constant. The data blocks played back from the medium are sequentially stored in a memory at the internal data transfer clock rate, which is also utilized to control the scanner rotation. The data is read from the memory at a constant rate which is adjusted for each particular operation. A memory status control signal is m provided indicating a predetermined level of fullness obtained by the memory. That control signal is compared in time to a control signal indicating occurrence of the beginning of a next data block.