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 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 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: 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 system and method are described for aligning a set of tracks which have been recorded simultaneously on a magnetic medium by a multichannel transducer mounted in a rotating scanner, with transducing channels of a corresponding multichannel transducer for reproduction. A scan identifier signal is recorded simultaneously by a rotating multichannel transducer at a predetermined location along each track. Means are provided for reproducing and summing simultaneously accessed scan identifier signals during consecutive scans of the multichannel transducer over the medium. The relative position of the recorded medium to the rotating multichannel transducer is changed in a direction across the length of the tracks. That relative position in which the largest amplitude of the summed scan identifier signals is obtained corresponds to the desired alignment with the set of tracks.

Abstract: A magnetic shield is provided for stray flux reduction from a transducer into a laterally disposed adjacent transducer. The shield substantially covers the transducing winding and extends in close proximity over a rear portion of the magnetic core. The shield does not extend over the transducing gap, to prevent magnetic coupling therewith. In the preferred embodiment a staggered two channel video type transducer has shields on opposite sides thereof in direct contact with the cores. The shields have recesses to accommodate the windings.

Abstract: Digital data is received on a plurality of input channels at unrelated, asynchronous input clock rates. The data is multiplexed and transmitted via one or more synchronous parallel channels, together with encoded information related to the original asynchronous input clock rate on each channel. The data received from the synchronous channels is demultiplexed and redistributed to proper output channels and clocked out therefrom at rates derived from the encoded and reconstituted asynchronous clock rate information from each channel.

Abstract: A digitally controlled motor drive system using a pulse width modulated motor drive receives a desired motor velocity signal and an actual motor velocity signal and it provides a corresponding velocity error signal. The velocity error signal is adjusted in response to a change in the value of a power voltage supplied to the motor. The velocity error signal may be compensated for back electromotive force and/or for static friction in the motor, if desired. The system is simple, reliable and cost effective.

Abstract: A position servo system is described for positioning a member mounted on a spring. The spring provides a force opposing the motion of the member from an initial position. A position actuator, for example a motor, applies a force in response to a position request signal for moving the member to a desired position. A portion of the position feedback signal is applied from a position sensor to the motor as a positive feedback signal to compensate for the force of the spring. A steady state position error of the servo system is thereby substantially reduced to zero. A circuit and method for calibrating the positive feedback signal are also described.

Abstract: An apparatus is described for filling notches in a notched workpiece with a soft filler material having a viscosity similar to glasses. The apparatus has a bottom portion which receives the notched workpiece and a top portion. The top portion has a lower surface adapted to apply a concentrated pressure in the direction of the bottom portion to enhance flow of the soft filler material into the notches when that material is inserted between the assembled top and bottom portions.

Abstract: An adaptive velocity change profile for control of a video tape transport apparatus during a cue mode. The tape transport apparatus moves the video tape to a cue point in the shortest time available by adapting a deceleration velocity change profile to the actual ballistics of transport of the tape. When in a cue mode, the transport uses a commanded velocity signal generator to produce digital numbers which are applied as a reference speed signal to a velocity servo driving the takeup reel of the transport. For distances separating a selected frame location on the tape from the cue point greater than a predetermined distance, the commanded velocity is the maximum available from the transport. For distances to the cue point less than the predetermined distance, the commanded velocity is generated from an adaptive cue profile which decelerates the transport of the tape quickly as the selected frame location approaches the cue point without overshooting the mark.

Abstract: A method and system are provided for generating a synchronized handshake between communicating parts of a digital system operating from a common clock. A request signal is sent from an initiating station to a responding station. The responding station acknowledges receipt of the request by sending an acknowledge signal back to the initiating station, thereby completing a so-called handshake. In accordance with the invention both the request and acknowledge signal are pulses of a fixed duration greater than one but less than two clock cycles. A new request signal may be transmitted concurrently with the reception of an acknowledge signal, resulting in a maximum handshake rate of one half of the common clock rate.

Abstract: A broadband switching circuit has two or more field controlled switch elements coupled in series between an input terminal and an output terminal. A passive, lossy network is coupled between a junction of consecutive switch elements and a virtual around. The off state isolation of the switch elements is improved and signal losses are reduced significantly. When utilized in multichannel switching circuits, only a single switching voltage polarity per channel is required.

Abstract: A method and system for composite system phase control in a signal processor such as a television video recorder operating in a genlocked system. A synchronizing signal, preferably a frame-rate horizontal reset pulse, is generated in response to coincidence between predetermined parts of two timing reference signals, in particular color television frame-rate horizontal line reference pulses and clock pulses derived from the color subcarrier. Possible coincidence ambiguity between the two timing reference signals exists when transitions in the two signals occur within a predetermined time period. The phase of one of the reference signals, the subcarrier frequency clock, is shifted 180 degrees (one-half cycle) to eliminate the potential coincidence ambiguity.

Abstract: Information related to the beginning of data and the phase of color burst on consecutive horizontal scan lines of a digital color television signal is encoded into a variable width pulse. A first transition of that pulse has a predetermined phase relationship with the beginning of data on each line. A second transition of the variable width pulse is formed by providing a delayed transition with respect to the first transition in a variable delay circuit. The second transition is delayed by different amounts of delay, each corresponding to a particular predetermined color burst phase on that particular line.

Abstract: A nonmagnetic holder is made having a plurality of precisely located parallel grooves. Each groove has a reference lateral surface provided therein. Individual magnetic transducers are inserted in each groove with a lateral surface abutting the reference lateral surface within that groove. The transducers are preferably made by well known batch fabrication techiques. A locating element, such as a leaf spring, is provided in each groove to urge the transducer core against the reference surface and to firmly hold the transducer in a desired position during alignment and assembly. The modular structure allows inspecting the individual transducers for mechanical or electrical damages and their replacement, if necessary, prior to the final assembly. The multichannel head is then integrally joined together, for example by bonding. The rejection rate of the resulting modular multichannel head is significantly reduced.

Abstract: There is disclosed herein an apparatus and method for accurately ascertaining the time of occurrence of passage of the leading and trailing edges of an input pulse through the 50% amplitude level. The apparatus implements the transfer function 1 - cos(wt) where t is equal to the round trip delay through a delay line, and w is the angular velocity of each fourier component of the input signal. In one embodiment, a summing resistor and a delay line having a characteristic impedance equal to that of the resistor are used. The output of the delay line is coupled to one input of a comparator, and the other input is coupled to the junction between the summing resistor and the delay line. Another embodiment uses two matched delay lines, two factoring circuits, a summing circuit and a comparator to implement the same transfer function.

Abstract: A reference track is recorded in a longitudinal direction on a recording medium. During recording of an information signal along parallel tracks on the medium a deviation of the reference track in a transverse direction from its nominal position with respect to the medium transport is detected by one or more sensor heads mounted in a fixed relationship with respect to the medium transport. A positionably mounted data head is moved in transverse direction in accordance with the sense and magnitude of the detected deviation, thereby maintaining the data head in a known geometric relationship with the reference track during the recording process. During playback the same reference track may be utilized to follow the thusly recorded parallel tracks.

Abstract: A nonmagnetic holder is made having a plurality of precisely located parallel grooves. Each groove has a reference lateral surface provided therein. Individual magnetic transducers are inserted in each groove with a lateral surface abutting the reference lateral surface within that groove. The transducers are preferably made by well known batch fabrication techniques. A locating element, such as a leaf spring, is provided in each groove to urge the transducer core against the reference surface and to firmly hold the transducer in a desired position during alignment and assembly. The modular structure allows inspecting the individual transducers for mechanical or electrical damages and their replacement, if necessary, prior to the final assembly. The multichannel head is then integrally joined together, for example by bonding. The rejection rate of the resulting modular multichannel head is significantly reduced.

Abstract: A voltage controlled equalizer has two parallel signal paths. A first signal path is provided by a delay line coupled to an input of an amplifier. A control circuit is coupled between an input of the delay line and an output of the amplifier, via a second, parallel signal path. A control signal is applied to the control circuit to adjust the gain of the second signal path, thereby adjusting an amplitude versus frequency response characteristic of the equalizer. Signal delays caused by the control circuit are preferably selected substantially equal to those of the amplifier to compensate for undesired phase shifts of high frequency signals in the second signal path.