Abstract: An automatic gain control circuit for an interferometer or a phase sensitive detector reduces sensitivity to fluctuations in amplitude of input signals. A pair of currents from the phase sensitive detector that represents a detected phase difference are input to an automatic gain control ratio detector. The output of the automatic gain control ratio detector is a function of the ratio of the difference and sum of the phase sensitive detector currents that is substantially independent of intensity or amplitude fluctuations of the input signals.

Abstract: An interface circuit permits a first bus master connected to a first bus to directly access a main memory connected to a second bus while maintaining coherency between corresponding data in the main memory and a cache memory used by a second bus master on the second bus. The interface circuit maps selected first bus addresses to corresponding second bus addresses such that when a bus master on the first bus attempts to read or write access one of the mapped first bus addresses, the bus interface circuit responds by read or write accessing a corresponding address in the memory on the second bus.

Abstract: An improved swept frequency domain reflectometry instrument has an input/output terminal coupled to one end of a cable. A radio frequency at the input/output terminal is converted to an intermediate frequency using a swept local frequency. The radio frequency is derived from the swept local frequency and a variable offset frequency. A controller controls the variable offset frequency, monitoring the amplitude of the intermediate frequency. A period counter counts the intermediate frequency at a first maximum response of the intermediate frequency and further counts the offset frequency at a second maximum response of the intermediate frequency. The location of a discontinuity in the cable is calculated from the counted frequencies.

Abstract: A dense, sintered ceramic material having a low dielectric constant, a low firing temperature, and a low coefficient of thermal expansion is provided from a mixture of 0-30 wt. % alumina, 30-60 wt. % fused silica, and 30-70 wt. % of a glass comprised of PbO, B.sub.2 O.sub.3, and SiO.sub.2. The mixture has a minimum sintering temperature in the range of 800.degree.-900.degree. C., and can be formed by conventional manufacturing techniques. It is particularly useful for the fabrication of single or multilayer electronic circuit substrates.

Abstract: An easily reconfigurable DUT board interconnection grid is electrically and mechanically reliable, has low noise and cross-talk, and permits high density mixed digital and analog devices to be tested. This DUT board includes a grounding block of conductive material that has an inner and outer array of holes and is in electrical contact with the circuit board ground. The arrays of holes correspond in shape and size to, and are in electrical contact with, underlying inner and outer array of conductive members in the circuit board. Each conductive member provides a pin in the center of the corresponding hole to make each hole a coaxial contact receptacle. The inner array of conductive members connects to the sockets or pads that receive the device-under-test on the DUT side of the circuit board to the other side of the circuit board where the grounding block resides. The coaxial contact receptacles of the inner array therefore present an interface to the DUT.

Abstract: A print medium sheet feeding system for an ink jet printer having a print head with a planar array of jets is provided by clamping the leading edge of a paper after it is passed through a printing zone to a rotating assembly of parallel disks. The sheet is pulled through the printing zone by rotating the disk with the clamp being carried with the rotating drum. A platen may be provided which has a flat surface in the printing zone forming a tangent to the outer surface of the rotating disks. Alternatively, the platen may be removed and the sheet held in tension between the clamp and a nip region formed by a spring plate held against a restraining plate. In an alternative embodiment, the sheet is initially clamped against the drum by the combination of a lever arm which is selectively engagable with the drum for rotation therewith and an attached actuating arm having a plate which secures a sheet to the drum surface.

Abstract: A logic analyzer stores the activity around the last in a series of triggering events while also storing the activity around several other triggering events immediately preceding the last trigger. The acquisition memory is first positioned into a number, N, of memory sections and the trigger condition of interest is defined. Then repeated acquistions are performed using this same trigger condition. At first, data from each of these acquisitions is stored in each one of the number of memory sections. When all of the memory sections have been filled once, if the trigger condition is still occurring, the acquisition memories are reused in the same order in which they were originally used as many times as necessary until it is ascertained that the trigger condition is no longer occurring or some external conditon has changed, at which time the logic analyzer is stopped. One of the memory sections then contains the data that occurred in the vicinity of the last trigger.

Abstract: The charge transfer efficiency of a two-phase charge-coupled device cell is enhanced by providing a three-tiered built-in potential in the channel of each cell. Two lower potential tiers form a trenched potential well in the cell for storing charge. A higher potential tier between the trenched potential well of a cell and the potential well of a preceding neighbor cell provides a potential barrier preventing backflow of charge from well-to-well. The potential trench is located at the downstream end of the well adjacent a succeeding neighbor cell of the CCD.

Abstract: An improved optical time domain reflectometer, OTDR, has a reference fiber interposed between an optical coupler and a front panel connector for acquiring a reference backscatter level that is independent from a fiber under test. The reference level is used to determine the quality of the front panel connection between the OTDR and the fiber under test and for verifying and adjusting transmitter and receiver circuitry in the OTDR. The reference fiber also allows the acquisition of front panel connector reflection data when a Bragg Cell is used as the optical coupler.

Abstract: An improved electrical test probe has a electrically conductive strain relief adapter mounted on a substrate for accepting a conductive cable having a central conductor and an outer shielding conductor separated by a dielectric layer. The conductive cable is inserted into the strain relief adapter with the outer shielding conductor in electrical contact with the adapter. The substrate is disposed within an electrically conductive elongate hollow body with the body being deformed proximate the location of the strain relief adapter to secure the substrate in the body and to provide electrical continuity between the outer shielding conductor and the substrate and the outer shielding conductor and the hollow body. The adapter further provides strain relief for the center conductor of the conductive cable and mechanical support for the substrate.

Abstract: A low distortion optic fiber network having a feedback system which injects pilot tones into a base band input signal directly modulating an LED, optically detects the output resulting from the pilot tones, digitally samples the detected signal, and generates correction coefficients. The correction coefficients and the base band input signal are input to a correction circuit that pre-distorts the input signal in a non-linear manner and uses the distorted signal to modulate the LED. Pre-distorting the LED input signal compensates for the non-linearities of diode transfer characteristics and intermodulation between signals in the network thereby reducing harmonic and intermodulation distortion.

Abstract: A probe head for establishing electrically conductive contact with an electronic device comprises a loading member having an attachment portion for attachment to a support structure. A cantilever arm is attached at a first end to the attachment portion and has a second end spaced from the attachment portion. A flexible sheet of insulating material is attached at a first end region to the second end of the cantilever arm with a first main face of the flexible sheet confronting the cantilever arm. A first array of contact elements is exposed at the second main face of the sheet at the first end region thereof, whereby the sheet of insulating material is between the cantilever arm and the contact elements of the first array. A second array of contact elements is exposed at a second end region of the sheet, spaced from the first end region, and conductor runs connect the contact elements of the first array with respective contact elements of the second array.

Abstract: Printing is by an array of color-printing elements or nozzles in order ot produce interlaced color printing while printing each line only once with each color. Print head array configurations for printing two, three and four colors include linear and parallel arrays. In one embodiment, a first color and a second color are printed on alternate lines of a first set of print lines. The first color and a third color are printed on alternate lines of a second set of print lines. Also, the second color and the third color are printed on alternate lines of a third set of print lines. By sequentially printing these consecutive sets of lines on a print medium, with each of the three pairs of colors, all of the lines of an image are printed once with each color. Other color-printing configurations are also shown.

Abstract: An antistatic, low particulate shipping container for an electronic component having an open package design has a circuit board conductively plated on top and bottom with plated through holes in the configuration of the pins of the open package electronic component. Socket pins are press fitted into the through holes. The circuit board is secured within a conductive box so that the tips of the socket pins contact the conductive box and so that the edges of the circuit board are sealed. When the electronic component is mounted on the circuit board, the pins of the component are shorted together and to the conductive box to provide protection against ESD damage. A slide-on cover with an integral window is slipped over the electronic component to protect the exposed portion of the component from contact and to provide visual inspection of the component.

Abstract: An interface circuit board connected to a VMEbus standard backplane bus of a first data processing system, and also to a Futurebus standard backplane bus of a second data processing system, provides address/data conversion and interrupt service between the two standard bus structures. The Futurebus, being a higher level bus than the VMEbus, has no provision for hardware interrupts; event related data are conventionally transmitted across the Futurebus like any other data item. The interface board signals VMEbus interrupts to Futurebus devices by way of the Futurebus bus arbitration facility. Interrupts generated on the interface circuit board and interrupts from the VMEbus priority interrupt bus are mapped and converted into message numbers, one of which is asserted on the Futurebus arbitration bus as an arbitration number higher than the arbitration numbers assigned to Futurebus devices.

Abstract: A touch panel has panel scanning signals selectively applied to the four sides of a touch sensing surface of the panel so as to establish alternating current voltage gradients in desired directions across the touch sensing surface. When the panel is touched, touch signals result and are utilized by a touch location circuit in determining the location of touch. The impedance touch current resulting from a user's touch may also be determined and used. The touch panel circuit automatically filters the touch signals to an extent which varies depending upon the rate of movement of touch from one location on the touch sensing surface to a subsequent location. Filtering is decreased with the increasing rates of movement. The touch panel thereby minimizes the effects of noise on touch location determination.

Abstract: An accurate delay generator circuit for delaying the rising and falling edge of an input signal includes: a current switch having an input for receiving the input signal, first and second current inputs, and a current output; a p-channel transistor coupled to the first current input of the current switch; a first threshold voltage generator coupled to the gate of the p-channel transistor for generating a voltage equal to twice a p-channel threshold voltage with respect to VDD; an n-channel transistor coupled to the second current input of the current switch; a second threshold voltage generator coupled to the gate of the n-channel transistor for generating a voltage equal to twice an n-channel thresold voltage with respect to ground; a capacitor coupled to the output of the current switch; and an output inverter stage coupled to the output of the current switch for providing the delayed input signal.

Abstract: A method for generating a stimulus signal for conducting frequency response function calculations maximizes the overall dynamic range of the calculations possible by balancing the requirements for dynamic range between the input channels of a Fourier analyzer used for monitoring the input and output of the system under analysis. A preferred version of the method includes the steps of estimating the frequency response function of the system under analysis, inverting the estimated frequency response function, taking the square root of the inverted estimated frequency response function, randomizing the phase of the inverse square-root estimated frequency response function, converting the phase-randomized inverse square-root estimated frequency response function to a time domain test signal, scaling the time domain test signal as necessary to produce the stimulus signal for conducting frequency response function calculations.

Abstract: An electro-optic device comprises a substrate of electro-optic material having at least one optical waveguide formed therein subjacent a main surface thereof for propagating an optical mode. A coplanar transmission line is formed on the main surface of the substrate and has at least first and second electrodes spaced apart by an electrode gap that is wider than the first electrode. The center of the waveguide is within the electrode gap and closer to the first electrode than the second electrode.

Abstract: A transformer-based coupling network permits a push-pull amplifier to be used with single ended signals, while providing constant gain and, if desired, bidirectional impedance matching, from RF down to DC.