Abstract: The invention concerns a process for detecting the zero crossings of a data signal by employing of a comparator. To be able to accurately detect zero crossings even when the data signal is distorted due to transmission over a system with filtering characteristics, an auxiliary voltage corresponding to half the value of the difference between the measured maximum value of the data signal and the measured minimum value is generated. An additional voltage is formed by comparing a reference quantity that is proportional to the auxiliary voltage with the respective instantaneous value of the data signal and is added to the auxiliary voltage to form a total voltage. The total voltage is used to form the reference voltage of the comparator.

Abstract: Methods for producing logic signal displays for an instrument known as a "logic oscilloscope" are disclosed. A digital input signal is first sampled as an analog signal to produce multi-bit digital samples that are representative of the amplitude of the input signal over time. The multi-bit digital samples are then processed using interpolative techniques to ascertain when the input signal crossed a hypothetical logic level threshold or pair of thresholds and when the signal was in one logic state or the other. The resulting transition times and logic states are then used as the basis for generating a variety of digital displays, including logic timing diagrams, state table displays, and cursor readouts similar to those available in a logic analyzer. Setup and hold time violations and measurements may also be obtained using this information.

Abstract: An electronic instrument with a housing having a battery compartment. The housing has a probe connector oriented on a probe axis, so that a probe may be connected to the instrument via the connector for interfacing with a device under test. A removable battery cover encloses the battery compartment, and has a probe aperture registered with the probe connector, so that a probe may be connected when the battery cover is installed. To prevent removal of the battery cover when a probe is connected to the probe connector, the battery cover is constrained against movement along the probe axis. In addition, the battery cover may contain a conductive safety element necessary to complete a circuit between the battery and other components in the instrument, so that the batteries are capable of delivering power only when the cover is properly installed.

Abstract: A differential attenuator is described that is capable of automatic calibration using electronically adjustable circuit elements. The differential attenuator has positive and negative inputs and outputs. A resistor and capacitor couple the positive side input and output, while a matching resistor and capacitor couple the negative side input and output. Shunt resistors and shunt capacitors coupled to the positive and negative outputs are augmented and made electronically adjustable by multipliers having their signal inputs coupled to the respective side output nodes. The outputs of one set of multipliers are coupled to the other ends of the shunt resistors, while their multiplication coefficients are controlled by a dc.sub.-- control signal. The outputs of another set of multipliers are capacitively coupled back to their respective side output nodes, while their multiplication coefficients are controlled by an ac.sub.-- control signal.

Abstract: A method for evaluating an electrical signal is disclosed. This method is especially useful for evaluating analog signals within an integrated circuit or other inaccessible location. A reference histogram is derived from either a simulation of a desired waveform or from sampling a desired waveform signal. This reference histogram is subtracted from a test results histogram to produce a variance histogram. The variance histogram can be further evaluated to determine characteristics of the electrical signal under test and/or to produce a figure of merit for the circuitry producing the signal under evaluation. Before the difference between the test results histogram and the reference histogram is taken, normalization, offset calculation, gain adjustment, and noise floor adjustment may be performed on the test results histogram, and these values may be exported to further aid in characterization of the signal under evaluation.

Abstract: An injector/ejector mechanism with a lever pivotally connected to a module faceplate to pivot about a pivot axis. The lever has a handle extending away from the faceplate, and a latch portion extending away from the faceplate in a direction opposite the handle portion. The latch portion includes a first tooth and a second tooth, the first tooth being positioned farther from the faceplate than is the second tooth, The lever is movable between a first position in which the first tooth extends laterally from the pivot axis by a limited first amount, and a second position in which the first tooth extends laterally from the pivot axis by a greater second amount, and the lever is spring biased toward the first position.

Abstract: An integrated digital processing device and method for examining the operation thereof. An integrated multiple digital processing device has externally-accessible tag connections which provide signals representative of what circuit has access to external memory used by the processing device. The processing device includes a plurality of digital processor circuits, a DRAM refresh logic circuit, externally-accessible connections for receiving memory access signals from an external processor, and an arbitration circuit for determining which of the digital processor circuits, refresh logic circuit or external processor may have access to the external memory. The signals on the tag connections are provided by the arbitration circuit, and indicate which of the aforementioned circuits has access to the external memory at any moment.

Abstract: A method and apparatus for producing self-diagnostic information from a circuit board. A circuit board is provided with an on-board processor, an on-board ROM containing diagnostic test software, a frequency generator adapted to produce an electrical signal having a predetermined frequency when an unacceptable response is determined, wherein the predetermined frequency corresponds substantially to the event within the diagnostic test sequence of a particular test for which an unacceptable response is determined. The signal is presented at an output terminal of the circuit board. The status of the circuit board is determined by measuring the frequency of the signal at the output terminal and comparing that frequency to an index of corresponding defects.

Abstract: An actuating device for a pinch roller in a tape recording and/or playing device has a capstan spindle driven by a mechanism supported on a chassis. A pinch lever supports the pinch roller. At least one drive lever is rotatably coupled to the pinch lever and mounted to pivot about a fixed axis normal to the chassis for swiveling the pinch roller between resting and working positions. A spring connects the pinch lever and the at least one drive lever for urging the pinch roller against the capstan spindle only in the working position. A first guide controls the swiveling of the at least one drive lever. A lift roller is rotatably supported by the pinch lever and disposed in proximity to the pinch roller. The lift roller has a cylindrical region and a conical region having a diameter which increases in a direction away from the chassis.

Abstract: A circuit in accordance with an inventive arrangement comprises: a signal generator for a correction signal having a substantially parabolic shape at a scanning rate of the video display; a waveform clipper coupled to the signal generator for the correction signal, the waveform clipper having a current sink transistor coupled to the signal generator for the correction signal for clamping the correction signal, and a reference transistor coupled to a base of the current sink transistor for providing a reference voltage; and, a switch for disabling the reference transistor during excursions of the correction signal and enabling the reference transistor during clamping. The switch may comprise a switching transistor coupled to the reference transistor and to the correction signal, the switching transistor disabling the reference transistor during excursions of the correction signal and enabling the reference transistor during clamping.

Abstract: Program related data contained in the broadcast signal of an advertisement for a future television show are evaluated and compared with the current TV set tuning when a LEARN button on a remote control is pressed. A VCR tunes to the present TV channel and stores the program related data for the future television show. The apparatus also ensures that a program to be recorded will start and end at the right time and that broadcast advertisements will be skipped during recording, are disclosed.

Abstract: A symmetrical square wave, having zero average value, is coupled to the input of a horizontal deflection yoke through an S-shaping capacitance. A negative resistance coupled to the output of the yoke has a negative resistance value which compensates for resistive losses in the yoke. A yoke current generated in the yoke will be a symmetrical triangular waveform. A first control loop adjusts the negative resistance value to assure successive zero value crossings of the yoke current are coincident in time with each center of successive horizontal scan lines. A second control loop adjusts the square wave to assure successive level transitions of the square wave are coincident in time with successive changes of scanning direction.

Abstract: A magnetic tape cassette recorder, comprising: take-up and feed spools for winding and unwinding a magnetic tape carried in a removable cassette; a tumbler gear mounted for swinging motion about a stationary shaft and movable between the take-up and feed spools; a motor, disposed outside the cassette when the cassette is operatively inserted in the recorder, for selectively driving the take-up and feed spools through the tumbler gear; a capstan driven by the motor; a pinch roller for pressing the magnetic tape against the capstan; a transmission mechanism driven by the motor and having a planetary gear assembly, including a planet carrier, for driving the tumbler gear; first and second annular coupling parts rotatably stacked along the stationary shaft; a third coupling part connected to the planet carrier and rotatably stacked between the first and second coupling parts, defining respective sets of opposing facing surfaces between the third coupling part and each of the first and second coupling parts; a fri

Abstract: In order to increase the speed of the transfer of control data to an OSD circuit, and to eliminate "holes" in memory caused by the use of memory mapped registers, dual use is made of the serial data port of the OSD circuit to accomplish two distinct tasks, serial transfer of graphics data and serial transfer of the control data. The on-screen display apparatus includes an OSD circuit for generating an graphics signal for display on a display screen, a controller coupled to the OSD circuit, for controlling the OSD circuit, and a VRAM including a first area for storing graphics data and a second area for storing control data for the OSD circuit. The VRAM has a parallel input/output port coupled to the controller and a serial output port coupled to the OSD circuit, the serial output port conveys the graphics data from the first area of the VRAM to the OSD circuit for processing and display.

Abstract: A VCR or laserdisc player includes circuitry for detecting a code provided by VCR tapes, tape cassettes, or laser videodiscs, which indicates that the material recorded on the videotape or videodisc has been recorded in a compressed fashion to enable proper playback on a 16.times.9 television receiver. In response to detection of this code, the VCR or laserdisc player applies a DC signal to the chrominance output terminal of its S-Video connector. Circuitry in the television receiver detects the DC signal on the chrominance terminal of its S-Video input connector, and controls a wide-screen processor to expand the image by displaying it over the entire width of the 16.times.9 display screen.

Abstract: A method of transmitting and decoding biphase coded signals individually representing separate data services and inserted in the line blanking interval of a video signal greatly increases the probability of avoiding the effects of anticoincidence errors. A unique start code is allocated to each of the data services prior to transmitting the video signal. The video signal is separated into the separate data services without field or line windowing. Every pair of biphase elements occurring after the start code is checked for anticoincidence errors, and all wanted bits are stored in a buffer memory. The wanted bits are transferred from the buffer memory to an output memory only when no anticoincidence error has occurred between the start code and the last wanted bit.

Abstract: A cordless telephone system includes a single base unit and at least two remote handunits, where the base unit employs two transmitter channels coupled together through a low impedance and coupled to a single antenna. The transmitter channels include voltage controlled crystal oscillators (VCXOs) and frequency tripler circuitry, rather than PLLs in order to keep intermodulation distortion at the outputs of the transmitter amplifiers to a minimum.

Abstract: An IR repeater is disclosed which is resistant to CFL interference. The IR repeater includes a receiver section for receiving an IR light signal representing a coded signal modulated by a modulating signal, and for detecting the coded signal. An oscillator generates a transmitter modulating signal, and a transmitter section, coupled to the receiver section and the oscillator, generates an IR light signal representing the detected coded signal modulated by the transmitter modulating signal.

Abstract: A reset signal generator includes circuitry for detecting conditions indicating that a reset signal is necessary and generating a reset signal in response. Such conditions may include low power supply voltage (i.e., "brown out") or the presence of transient signal spikes. Circuitry is provided for extending the duration of the reset signal after power is initially applied, because at this time associated digital circuitry may not be fully powered-up, and may require a longer than normal reset pulse. In contrast, a reset pulse of a normal duration is generated when the digital circuitry is fully powered-up and a transient signal spike is detected. Isolating circuitry is coupled between the detecting circuit and the extending circuit to isolate the detecting circuit from the extending circuit when there is no power-on condition, (i.e. when normal operating voltage is present) in order to prevent the duration of the reset pulse from being extended.

Abstract: A television receiver system having secondary picture display capability (such as PIP or POP) includes two tuners and signal processing arrangements, and circuitry for receiving a transmitted channel guide. In response to a "BROWSE" command, the receiver maintains the currently-tuned first channel as the source for the main picture, displays text related to a television show on a second channel, activates the secondary picture display circuitry, and tunes the second tuner to the second channel. In this way, the viewer can simultaneously get the benefit of both a text description of the television show on the second channel and view a secondary image of the television show on the second channel, without tuning away from the first channel supplying the main picture.