Abstract: A movable actuator supporting a stacked assembly of read/write heads for unitary movement adjacent respective disk surfaces of a disk drive mechanism, the movable actuator incorporating a series of secondary actuators, one for each head, each secondary actuator including a bimorph member with piezoelectric properties, and capable of extremely precise movements for secondary positioning.

Abstract: A tape transport capable of receiving cassettes of varying sizes, one at the time for play, includes a cassette indexing mechanism capable of selectively positioning the spindles which engage the reels of an associated cassette at a selected distance corresponding to the reel-center-to-reel-center distance of the cassette. Mis-insertion apparatus associated with the transport provides that any cassette smaller than the cassette receiving opening in the transport will be protected against being improperly inserted into the transport.

Abstract: A system and method for driving a stepper motor utilizing a near minimum amount of driving power is described. A stepping detector is utilized to determine whether the motor has actually stepped in response to a driving power applied thereto. When it is determined that the motor has stepped, the magnitude of the driving power is decreased. When the stepping detector indicates a stall condition, the driving power is increased. As a result, the motor operates near stall condition and power consumption is minimized. In the preferred embodiment during each consecutive step a different phase of the motor is deenergized to conserve power. By stepping the motor a voltage pulse is induced into the deenergized phase. The polarity and magnitude of that voltage pulse are examined after each step to determine whether the motor has actually stepped. The use of the deenergized phase to ascertain motor status eliminates the need for an external stepping detector.

Abstract: A pivotable control level disposed between a pair of spaced plates, with a motion resisting element mounted on the lever and compressed by the plates to provide a constant resistive force or "feel" to the system operator. A separate adjusting mechanism selectively increases or decreases the amount of compression exerted by the plates on the element to either increase or decrease the resistive force felt by the operator.

Abstract: A recording and reproducing system for radar signal information includes a pulse stretcher that detects master trigger pulses and, upon each occurrence, provides a stretched pulse having extended duration consistent with a selected recording bandwidth; a detector to detect the stretched pulses and to provide a binary information signals; an echo pulse processor to sample and quantize radar echo pulses to at least one bit level. The quantized echo pulses are recorded on multiple channels and the binary information signals are recorded on a single channel of selected bandwidth.

Abstract: A decoder system for decoding signals such as Class IV partial-response signals. In the decoder system, threshold levels are used to distinguish between binary ones and zeros in partial-response signals. The threshold levels are adjusted by a feedback system to automatically compensate for effects such as signal dropouts.

Abstract: A head assembly which provides in the rotary scanner body a tape support structure including a scanner opening, a pair of magnetic heads mounted in the scanner opening for the reading and writing of data on a magnetic tape medium, a support member disposed on the scanner body at the scanner opening and extending between the two magnetic heads to support the tape as it moves across the scanner opening, said tape support structure producing a dramatic improvement in signal output across the length of the head scan.

Abstract: A bidirectional transfer mechanism is provided for independent or simultaneous X-axis and Y-axis precision displacement of a mobile component, such as a video cassette pick-up unit for retrieving or returning video cassettes from a cassette library. The transfer mechanism comprises an upright column assembly supported on a machine frame for X-axis displacement and carrying the pick-up unit for Y-axis displacement. A first drive cable is connected to the upper and lower ends of the column assembly and threaded over a first set of pulleys on the machine frame, with a portion of the first cable being wrapped about a motor-driven winding drum for displacing the column assembly in the X-axis direction. A second drive cable has a portion thereof wrapped about another motor-driven winding drum and is threaded about a second set of pulleys on the column assembly and the pick-up unit, whereby drum rotation displaces the pick-up unit along the column assembly in the Y-axis direction.

Abstract: An electronic still store system stores and selectively outputs video image data defining a plurality of signal frame still images. The simultaneous display of up to 16 or more quarter sized images for scanning or sorting by an operator is facilitated by generating a quarter sized copy of each newly received image frame and storing both together on a conventional magnetic disk storage device as is typically employed in general purpose digital computing systems. The quarter sized image can then be recalled directly for a multi-image scan or sort function in which 16 reduced size images are displayed simultaneously without the time delays associated with the retrieval and size reduction of 16 full size images.

Abstract: A system and method for controlling the phase of an output signal relative to the phase of a reference signal are described. A function generator receives a phase control input signal and generates a predetermined periodic waveform having a selected phase displacement with respect to the phase control input signal. A desired phase displacement of the generated waveform is provided in a digital manner by selecting and storing a set of digital values representing samples of the phase displaced waveform. The phase displaced waveform is generated from the set of stored digital sample values.

Abstract: There is disclosed herein a system for digitally forming synchronization signals. In the preferred embodiment, these synchronization signals are for substitution in place of the original synchronization signals in a television signal. These digitally generated synchronization signals are generated synchronously with the digitization of the video portions of the television signal, and the digitally generated synchronization signals are multiplexed into the stream of digital video data in the appropriate blanking intervals. The system uses a first digital signal number generator to generate a plurality of digital signals which represent the peak amplitudes of the desired synchronization signals. A second digital signal number generator synchronously generates a second plurality of digital signal values representative of the shape of the desired edges for the synchronization signal being generated.

Abstract: A simplified apparatus for providing a profiled tape tension is described which does not require a tape pack diameter sensor. Desired tape tension profile values corresponding to various tape pack diameter values are stored in a tape tension profiler. A control signal indicative of the rotational speed of a takeup reel is applied from a reel servo to the tension profiler which, in turn, changes a tension arm adjustment command in response to changes in the reel speed. The control signal has a known relationship to the tape pack diameter wound on the takeup reel. In the preferred embodiment the control signal is sampled by the tape tension profiler and the samples are used to address a PROM in which the desired tape tension profile values are stored. The thusly addressed tape tension profile values are applied as position command signals to the takeup reel servo which, in turn, changes the position of the tension arm accordingly, thereby obtaining the desired tape tension.

Abstract: A serial data communication system including a microprocessor and an asynchronous communication interface adapter (ACIA) implementing a SMPTE Supervisory Protocol for Digital Interface Control. The system detects the beginning of a break character as the first framing error which occurs after the last word of a data block has been detected. The receive clock of the ACIA is disabled in response to the start of break detection by the software reset of a bistable device which disables a receive clock gate. The framing error detection circuit of the ACIA is additionally disabled by the termination of the receive clock signal. The end of the break character is detected as the space to mark transition before the start of the first word in the data block. The receive clock is enabled by setting the bistable device with the end of break transition thereby detecting the termination of the break character and enabling the receive clock gate.

Abstract: A system for editing videotape includes a subsystem to scan particular information lines within vertical blanking intervals and to identify particular lines that contain time code information, and a subsystem to generate time code information and to write the generated time code information at selected lines in vertical blanking intervals.

Abstract: Tape guides of a magnetic tape transport machine are controlled during movement by sensing the position of the member as it moves along a defined path in varying velocity corresponding to the position. The member is initially accelerated at a selected rate to a maximum velocity which is then maintained until a distance close to the end position is reached. Velocity is then reduced at a selected rate until another position closer to the end position is reached. At this position a final velocity is maintained until the end is reached. A determination is made of how closely the second distance from the end coincided with reaching the final velocity. The length of the first distance from the end position is adjusted to reduce the difference between the coincidence of reaching the second distance and the final velocity. Further, the sensed final position of the member is retained as the target final position for the subsequent operation.

Abstract: A composite analog video signal is sampled at precise locations relative to the phase of the unmodulated color subcarrier along each horizontal line of the video signal. This provides a digitized signal with a constant phase relationship relative to the unmodulated subcarrier phase, which relationship may be used to remove sampling clock phase errors. The digitized samples are filtered by a digital bandpass filter to remove DC and second harmonic noise distortion. Two phase error measurements of the actual sampling clock phase are taken by averaging two sets of burst samples at 0.degree. and 180.degree. crossings, respectively, on selected horizontal lines. These phase error measurements are separately stored, and then are updated on selected alternate horizontal lines to cancel sampling nonlinearity errors. The updated signals are differenced to provide a phase error signal indicative of any sampling clock phase errors.

Abstract: Errors in data words recovered following the transmission of digital data having internal correlation are concealed by substituting recovered correlated words for recovered words suspected of being in error. Concealment may follow the correction of errors according to an error correcting code. Error flag signals are used to identify corresponding respective recovered words that are suspected of being in error. These error flag signals are counted over a predetermined totaling interval, and a concealment interval signal is generated for a concealment interval when the count exceeds a predetermined threshold count. Recovered correlated words are substituted for recovered words corresponding to respective error flags and for all other recovered words corresponding to a respective concealment interval. In accordance with one aspect of the invention, the concealment interval is centered upon the corresponding totaling interval.

Abstract: Angular rotation of a member, such as the shaft of a tension arm assembly, is sensed by the combination of a circular type of magnet secured to the rotatable member and selectively polarized relative to its diameter to define a magnetic north-south pole pair, and a stationary Hall Effect transducing device secured in close and constant proximity to the ring magnet. A circuit coupled to the transducing device includes offset and amplification stages. In a preferred embodiment, the Hall Effect transducing device is located in the region of a magnetic null of the field generated by the magnetic poles, when the rotatable member is in a selected angular position. The constant gap between the transducing device and the circular magnet optimizes the generation of a linear output via the circuit, to accurately sense the member rotation.

Abstract: An apparatus and method for the extraction of vertical interval time code (VITC) included in the vertical blanking interval of a television signal reproduced from video tape transported past a rotating transducer over a wide range of speeds. VITC information is extracted at a rate derived from the rate of a control signal having a rate proportional to the velocity at which the tape is transported past the transducer.

Abstract: An apparatus and method for generating a rotating clock video wipe from two voltage ramps. The voltage ramps are rotated according to rotation data supplied by a controller. The rotated ramps are combined and fed to an output signal generator and then a video mixer.