Abstract: Two closely spaced magnetostatically coupled magnetoresistive elements are arranged with their respective planar surfaces in parallel. A nonmagnetic insulating material is interposed between the elements to prevent exchange coupling. Sense current flows simultaneously through both elements in the same direction and in perpendicular to the easy axis of magnetization. In response to signal fields applied in parallel with the sense current flow demagnetization components in the easy axis direction cancel. The output signal of the transducer is independent of recording track width and free of Barkhausen noise.

Abstract: A first digital data memory is responsive to a first clock signal varying at a rate in accordance with the timing errors contained in a stream of digital data to enter the digital data for temporary storage. The stored digital data is retrieved from storage in the first digital data memory in response to a second clock signal of a stable reference rate. The relative times of entering and retrieving the digital data in the first digital memory are set according to the occurrence of a selected sequence of digital data bits contained in the digital data. The digital data retrieved from the first digital data memory is further temporarily stored in a second digital data memory for an interval determined by the time difference between the occurrence of the selected sequence of digital data bits and the occurrence of a reference time signal.

Abstract: A magnetic tape cassette is provided with shielding means for the guide posts thereof, including a clip member of electrically-conducting material, for preventing build-up of static electrical charges and resultant clinging of the tape to the guide posts, when it is desired to pull the tape from the guide posts by vacuum pressure-differential apparatus, as for threading into a tape transport.

Abstract: A method and apparatus is disclosed for obtaining second order velocity error correction signals for use in a time base corrector that removes instabilities in a video information signal reproduced from a magnetic medium. The apparatus utilizes the phase of the color burst component of the video information signal from successive horizontal lines to determine the change in velocity error. The change in the phase of the burst components of successive horizontal lines is first used to generate a first order or straight line approximation of the velocity error, and the difference between successive changes in burst phase, from which two successive first order error approximations are generated, is used to determine the approximate rate of change of velocity error.

Abstract: A method and apparatus for detecting errors in the accuracy of multi-bit data words, i.e., a parity method and apparatus, is disclosed. The invention is intended for use in determining the accuracy of multi-bit data words that are being transmitted through a communication channel or are being recorded and reproduced using magnetic recording or other technique.

Abstract: Highly orientable acicular iron particles are made by reducing an acicular ferric oxide which has been formed into a porous matrix by combining it with sodium tripolyphosphate and reducing the oxide with hydrogen in the presence of a dehydrating agent.

Abstract: Apparatus is disclosed for providing compensation for missing, incorrect or otherwise defective data in a data stream preferably comprised of video information. The apparatus is particularly useful in a magnetic recording and reproducing system for digital video data signals. The apparatus effectively stores the digital video data that occurred 262 video lines prior to the current data at the input and continuously updates, (i.e., stores in place of) the stored data with current data unless defects occur in the current data, in which case the defective current data is not stored. The data from the store is inserted in the video data streams when the drop-outs or parity information associated with the data stream indicates that the current data is defective.

Abstract: A multiple leg magnetic transducer has two corresponding core portions abutting at a transducing gap plane. Each portion has a transducing gap defining pole and a multiple leg back core contiguous with the pole. A nonmagnetic side piece supports the pole and intermediate leg portions while a rear leg portion most distant from the pole is unsupported by the side piece. The thusly supported portions are pressed together in a direction towards the transducing gap plane while the rear leg portions flex in the opposite direction to obtain an intimate contact between all corresponding end faces of the abutting core portions. In the preferred embodiment the flexed leg portions are firmly supported by a bonding material.

Abstract: The transducer has a pole tip plate containing magnetic pole tips defining transducing gaps and a core housing providing electric shielding and containing magnetic cores engaging the poles. The tip plate has a first part of a wear-resistant, nonmagnetic, machinable material in the transducer-to-medium interface area, providing long wear, and an integrally joined contiguous second part of a conductive, nonmagnetic, machinable material, providing electric shielding.In accordance with the method, corresponding surfaces of a first block portion made of nonmagnetic, wear-resistant, machinable material and of a second block portion made of a nonmagnetic, conductive, machinable material are integrally joined together. Pole tips are secured into parallel grooves machined transversely to the joined surfaces to form a half-tip plate.

Abstract: Members of magnetic material are attached at a front end surface of a multichannel magnetic transducer to form an asymmetric magnetic circuit. A member is attached to one magnetic pole of each pair of poles forming a transducing channel. The members on consecutive adjacent channels are attached alternatively to poles located on the opposite sides of the transducer front end surface. The members are placed out of contact with the recording medium and at a distance from the transducing gaps to prevent magnetic coupling therewith, respectively.

Abstract: A control circuit generates a variable analog output voltage in response to momentary closure of touch control means by an operator. The control level selected via the touch control means is sampled, digitized, digitally stored and reconverted to the analog output voltage for driving a motor at a commensurate speed. Selection of a different control level generates a correspondingly different digital value and thus a different analog output voltage. The selected control level and the corresponding analog output voltage may be maintained for an extended period of time until a new selection is made, or a different operating mode is entered. A mode change causes an automatic reset to a neutral operating condition (e.g., zero analog output voltage).

Abstract: A total raster error measurement and correction circuitry, using digital memory means in the camera head for the storage of correction data, corrects spatial scan, shading, etc., errors in a television picture in two dimensions. The basic spatial error correction circuit effectively synthesizes horizontal rate waveforms on a number of discrete lines of the vertical scan. On all scanned lines between discrete lines, a linear approximation between the two discrete waveforms is made to form a vertically continuous waveform. Black and white shading errors are measured by comparing the black and white video levels against respective selected black and white D.C. levels with and without a cap on the camera lens. Gamma correction is provided by comparing the peak black and white levels to derive any gray level errors.

Abstract: A light emitting diode is modulated by the output signal of a F.E.T. amplifier, and the resulting light signal is fed back to the amplifier input via an optical fiber and a light detecting photo diode. Thus, current feedback is achieved with very flat frequency response over a full frequency band by modulating a light emitting diode with the preamplifier output signal, reconverting the resultant radiation to an electrical signal, which is then fed back to the preamplifier input.

Abstract: A digital circuit for generating a linearly increasing signal is provided for controlling the level of a recording A. C. bias signal. The digitally controlled bias signal is mixed with an analog signal of a known frequency and constant level and recorded. The circuit detects and stores a recording bias level corresponding to a reproduce signal envelope level, equal to an obtained peak level adjusted with respect to a known overbias level. The circuit compensates the detected recording bias level with respect to distance between the recording and reproducing heads to obtain an optimum recording bias level. The detected bias level remains stored and unchanged during power supply interruption.

Abstract: A high frequency, high resolution programmable timing signal generator provides periodic timing signals during a time period which is long with respect to the time resolution of the generator. The timing signal generator which is particularly applicable for generation of the composite sync signal (and numerous related signals) for a video television signal, includes a small, high speed random access memory wherein each word corresponds to a timing state and each output bit provides a sync video related signal. Other memory bit outputs operate in conjunction with control and timing circuitry to sequentially address the memory while permitting the memory to remain in a given state for predetermined time durations and to cyclically repeat selected state sequences. Memory word compaction is thus facilitated to permit the use of small, fast memories to provide precision implementation of complex timing functions over relatively long frame period intervals with wide flexibility.

Abstract: Apparatus is disclosed for recording video information signals on magnetic media by sampling the information signal and converting the samples to a plurality of component digital data streams which are simultaneously recorded on separate surfaces of a disc pack associated with a generally standard computer disc drive and for thereafter reproducing the plurality of digital data streams and recombining the same in a manner whereby the analog video information signal is reconstructed.

Abstract: A magnetic recording medium of improved durability is obtained by depositing a coating of silicon dioxide over a magnetic metallic film.

Abstract: A compensation circuit for overshoot, undershoot and delay occurring in response to sudden D. C. level changes in signals received by reactive filters. A D. C. level change, represented by an input signal step applied to the reactive filter is detected by the compensation circuit. The compensation circuit responsively provides a compensation D. C. signal step of a predetermined magnitude and polarity with respect to the input signal step. The compensation step is applied by the circuit to the signal return line of the reactive filter, simultaneously with the input signal step received by the filter to maintain a substantially constant D. C. signal level with respect to the reactive filter elements. The reactive filter elements are thus prevented from charging and discharging in response to the input signal step and filter delay is eliminated.

Abstract: Improved particles for magnetic recording are provided by coating gamma ferric oxide with a mixture of barium, strontium, lead or calcium and a trivalent iron oxide. The particles have enhanced coercivity and the coercivity is relatively unaffected by elevated temperatures.