Abstract: A method of compressing a digitized waveform into a sequence of N-bit words includes selecting corresponding bit values from N data words and generating a value based thereon. A next N input words are selected and the corresponding bits are used to generate a next value. The process is continued for each significant bit of the input sequence and the generated value stream is run-length encoded to produce a compressed data output stream.

Abstract: A file management system comprises a computerized data storage and retrieval utility for integrating data files produced by independent data processing operations by linking the data files according to user-definable relationships. The machine assigns user-definable attributes to the data files and their links and searches for groups of files and links having selected attributes. The machine also maintains an archive of versions of data files and their links referenced according to their creation time. The machine includes provisions for transmitting commands to a computer operating system when selected files are accessed or modified to invoke execution of user created programs.

Abstract: Calibrated voltage cursors with respect to an input waveform signal are produced for display with the input waveform signal by injecting the cursor signals into the signal path prior to any gain stages in the signal path.

Abstract: An acousto-optic modulator for use in an optical time domain reflectometer to test multimode optical fibers has an active material, such as As-Se-Ge or As.sub.2 S.sub.3 glass, that has a high figure of merit with a low insertion loss. The transducer for the modulator is configured to have a height that encompasses the multimode beam diameter at the optical wavelength, and a length that is consistent with a theoretical lower limit that is a function of the acoustic and optical wavelengths. Sufficient RF power is applied to the modulator to produce an angular efficiency, or optical throughput, that is sufficient to meet the specifications for the optical time domain reflectometer.

Abstract: An avalanche photodiode non-linearity correction circuit cancels a portion of a non-linear recovery error response by the APD to an input signal by using the fact that the non-linear recovery error is only mildly dependent upon the APD gain. The gain of the APD is varied from data acquisition cycle to data acquisition cycle, with the acquired data being stored. The stored data from consecutive data acquisition cycles are combined in a summation circuit to effectively cancel a significant portion of the non-linear recovery error response.

Abstract: A method for performing signal quality analysis on digital signals uses simultaneous dual threshold data acquisition. Using this method, the data need not be repetitive and, because the reference data and the variable data are acquired simultaneously, the logic analyzer continues to trigger and further measurements can be made after significant noise has been encountered. One threshold is designated the reference threshold and used to perform triggering and acquisition of reference data, while the other threshold is designated the variable threshold and used to acquire data for the noise margin analysis. At each increment of variable level, the data acquired by the reference acquisition and the data acquired using the variable threshold level is compared to see at what point in time and on what signal lines noise begins to affect the quality of the data.

Abstract: A device for simultaneously displaying unrelated signals processes the signals separately prior to inputting them to a multiplexer. Under control of a microprocessor the multiplexer. Under control of a microprocessor the multiplexer switches between the processed signals to alternately pass the signals to the deflection circuits of an X-X display device at a rate which does not interfere with other frequencies used in the environment where the device is used.

Abstract: A flat panel apparatus for and a method of addressing data storage locations (80) employs a row-scanning electron beam (76) to address simultaneously a row (120) of such storage locations and thereby store data in and read data out of them. The storage locations are defined by the overlapping areas of multiple column electrodes (62) extending in a common direction on a first substrate (82) and rows addressed by the electron beam and extending in a common direction on a second substrate (54). A layer of dielectric material (52) separate the first and the second substrates, which are positioned face-to-face and spaced-apart with the direction of the addressed rows transverse to that of the column electrodes. The column electrodes receive data drive signals.

Abstract: A system (11) for monitoring and controlling the movement of a mass (12) along a predetermined path (14) by a motor-driven flexible member (20) is provided to modulate the motor drive output so that the actual velocity of the mass corresponds more closely to the desired target velocity profile. The system preferably employs a dual loop servo system wherein an outer servo loop uses conventional linear encoding techniques and is supplemented by an inner servo loop utilizing a sensor (27) that detects a physical characteristic of the flexible member representative of the relative velocity of the mass. Relative velocity transducers utilizing magnetic circuits and operating according to variable reluctance principles for generating relative mass velocity signals directly are disclosed.

Abstract: A method of adjusting the gain of an operational amplifier using a digital-to-analog converter (DAC) based upon R-2R resistive ladder technology inserts the DAC between the output of the operational amplifier and the non-inverting input to form a positive feedback loop. Variations of a digital control code applied to the DAC to control the gain are not affected by corresponding variations in the output resistance of the DAC so that undesirable changes in the magnitude of output noise, drift, bandwidth and offset voltage are minimized.

Abstract: A method of normalizing fiber-optic loss measurements for wavelength uses a measured wavelength for a laser, a desired wavelength for the loss measurement, and a characteristic parameter for the fiber optic cable to perform a first order correction of the Rayleigh scattering from the fiber optic cable. The actual loss is measured using the laser and then corrected to produce the equivalent loss at the desired wavelength according to the equationLd=La+(Lm/1-La)(.lambda.m/.lambda.d).sup.4where Ld is the desired loss, La is the characteristic loss for the fiber optic cable, 1 is the length of the fiber optic cable, .lambda.m is the measured wavelength and .lambda.d is the desired wavelength. The resulting equivalent loss is displayed in an alphanumeric and/or a symbolic format.

Abstract: A high performance attenuator configuration divides a signal path into a plurality of parallel attenuator paths, each path having a predetermined attenuation value. A switch for each attenuator path is provided to couple selectively one of the attenuator paths to an input connector. Each attenuator path has an FET buffer amplifier, and the outputs of the FET buffer amplifiers are input to an electronic switch or multiplexer. The electronic switch selects the FET buffer amplifier output to be passed on to an output drive circuit.

Abstract: The present invention constitutes a pyrometer device and an associated method of operation for measuring temperature based on the radiation emitted by a heated body in which increased accuracy is achieved by actively ascertaining the emittance of the body whose temperature is being measured. The pyrometer device includes a light source for intermittently illuminating the heated body and a radiation sensing mechanism for measuring the amount of light reflected and radiated by the body. The pyrometer device further includes a signal processing unit for processing the information developed by the radiation sensing mechanism and deriving the temperature of the body based on a calculated emittance factor and the amount of light radiated by the body.

Abstract: A multi-standard vide option for an oscilloscope detects whether an input video signal has a bi-level or a tri-level horizontal sync pulse from a composite sync signal derived from the input video signal. A ramp signal is generated from the horizontal sync pulse having a slope of one polarity that changes to a slope of the opposite polarity when the horizontal sync pulse is tri-level. For a bi-level horizontal sync pulse the ramp is limited in magnitude and rapidly discharged at the end of the horizontal sync pulse. A digital output signal is generated from the ramp signal and has a width equal to the width of the horizontal sync pulse regardless whether it is bi-level or tri-level. From the type of horizontal sync pulse and the width or the number of lines per frame, a video standard is determined and is subsequently used to determine field identification and to automatically set up the horizontal sweep of the oscilloscope according to a selected video setup.

Abstract: A sintered body of tin oxide is made by forming a finely divided mixture containing at least about 0.2 weight percent ZnO, at least about 0.2 weight percent SiO.sub.2, up to about 0.5 weight percent Al.sub.2 O.sub.3, balance pure SnO.sub.2, with the sum of the proportions of ZnO and SiO.sub.2 being less than about 2 weight percent. The mixture is compacted and heated to a sintering temperature. The tin oxide may be doped with antimony.

Abstract: A system for providing input to a computer comprises a touchscreen apparatus for generating a grid of horizontal and vertical light beams and producing a set of output signals, each indicating whether a corresponding one of the light beams strikes an object. A scanning device repeatedly scans the states of the output signals, stores data representing the last scanned state of each output signal, and transmits a first interrupt signal to the computer whenever the state of any one of the output signals changes. In response to the interrupt signal, the computer reads the stored scan data, determines whether the data indicates that a horizontal and a vertical light beam is striking an object, and if so, sets parameter values to identify the horizontal and vertical light beams.

Abstract: An automatic masking system is used in an optical time domain reflectometer for implementing a method of compensating for relaxation transients in an optical receiver in the OTDR. The masking system drives an optical modulator that masks the optical reciver from high amplitude optical pulses in the return reflected light from a fiber under test. A masking pattern corresponding to the high amplitude optical pulses is generated from a first acquisition of data with the receiver unmasked from the return reflected light. The masking pattern is stored and used for generating a signal from the masking system to the optical modulator for blocking the high amplitude optical pulses in the return reflected light during a subsequent acquisition of data. In a third acquisition of data of the return reflected light, the optical modulator masks the receiver from the return reflected light.

Abstract: A technique for reducing the number of coefficients in a low ratio sampling rate converter divides each input sampling rate interval into a plurality of bins. For each bin a set of conversion coefficients is computed. So long as output data samples lie within the same bin, the same set of coefficients is applied. When the output data samples move to another bin, the set of coefficients applied is changed. Thus a finite set of coefficients are computed rather than computing an exact set for each output data sample.

Abstract: A stereoscopic graphics display system (10) includes a binocular viewing model generator (96) that automatically adapts a binocular viewing model to a selected stereoscopic image. An extrema accumulation unit (90) identifies extrema data corresponding to a region that bounds the selected image. The extrema data are delivered to the binocular viewing model generator, which designates a zero disparity location within the region and a disparity angle that is compatible with the dimensions of the selected image. The binocular viewing model generated in accordance with the selected image allow it to be rendered with improved three-dimensional qualities.

Abstract: A metastable sense circuit includes an input latch and a sense latch. The input latch passes data from the input to the output in a transparent mode and retains data at the output in a hold mode in response to a clock signal. The output of the input latch is coupled to an input of the sense latch. A logic signal is provided at the output of the sense latch responsive to an occurrence of a metastable state of the input latch in a transparent mode and retains data at the output in a hold mode in response to a clock signal. The input section of the sense latch includes a reference voltage generator that tracks changes in the logic switching threshold of the output of the input latch.