Abstract: A transmit/receive system for electromagnetic radiation, particularly radar, employs an array of active transmit/receive (T/R) modules. Only a portion of the modules are actuated to transmit or receive signals at any given time. Input transmit power is supplied to all modules, but only the selected portion of modules actually amplify their inputs. The power loss is thus kept small because the amplified signal power far outweighs the lost input power. This approach makes possible a monopulse signal routing scheme that minimizes the number of switches used and their accompanying reliability problems. Transmit and receive signals are routed through sum-and-difference circuits and respective sectors of the T/R modules such that during RECEIVE no switches are necessary to acquire a monopulse sum (.SIGMA.) signal, and only a single switch is required to acquire a monopulse difference (.DELTA.) signal. Similarly, no switching of module inputs is required during TRANSMIT.

Abstract: A high bandwidth chopper-stabilized amplifier operates main and auxiliary amplifiers at a randomized chopping signal frequency that substantially reduces intermodulation distortion between the input and chopping signals, clock noise and input voltage offset, thus making possible a significant increase in bandwidth. The circuit preferably uses a pseudo-random bit sequence generator to produce a pseudo-random chopping signal frequency.

Abstract: A wide dynamic range transconductance stage has two branches, each branch being composed of a plurality of transconductance circuit paths. Each circuit path has a greater transconductance than the other circuit paths for its branch within a respective sub-range of the input signal range for the stage as a whole, with each path dominating the other paths for its branch within its respective sub-range. The overall bandwidth for the stage, its g.sub.m, its noise characteristics and its input voltage range are enhanced as a result. Bandwidth and slew rate may be independently optimized by the designer. Two paths are used for each branch in the preferred embodiment, with one path consisting of a bipolar transistor and the other path either a field effect transistor or a resistor degenerated bipolar transistor. Multiple paths may be used based on the same principle.

Abstract: A head positioning system including contact means placing the head in a controlled position which includes means for allowing controlled repeatable motion about at least one of three mutually perpendicular axes. Translational means along each axis and transducer means about each axis and on each of the translational means may also be provided.

Abstract: A tool for countersinking nails into a workpiece has a base member, which is formed of resilient material, and has a generally flat bottom section resting on the workpiece. A metal guide is mounted in the base member. The guide has a central opening for receiving a nail in its bottom. A rigid cap member on the base above the guide has an aperture through it, and a nail set extends partially upward out of the aperture in the cap and extends into the opening in the guide above the nail for transmitting impact from a hammer on the nail. The bottom of the guide member is recessed from the bottom surface of the base so that the metal will not contact the workpiece. The cap has a greater diameter than the guide so that if the cap is struck when the bottom or the nail set is below the top of the workpiece, an impact on the cap is not transmitted to the guide but will be absorbed in the resilient material of the base. A nail starting section integral with the base member extends laterally outward.

Abstract: A cassette type cleaning device for a video tape recorder is disclosed in which a cleaning tape is carried on a pair of reels inside the cassette. The cleaning cassette may be inserted into a recorder and the cleaning tape advanced in moving the contact with the recorder heads and tape guides in the manner of a conventional video tape cassette. The cleaning tape has a non-abrasive surface contacting the recorder and is preferably formed from a synthetic suede material having a thickness of no more than about 0.4 mm, with a bristled surface on the side of the tape contacting the recorder heads. An aperture is provided in the side of the cassette housing in alignment with the tape wound about one reel, allowing cleaning fluid to be dispensed through the aperture onto the wound tape to produce an alternating wet and dry pattern, without exposing the tape by opening the cassette access door.

Abstract: A plurality of carriers for integrated circuit devices are each uniquely coded so as to be recognizable by an automatic decoding apparatus. The devices are tested and the test results accurately correlated with the appropriate devices by recording the test results for each device, reading the identification code for each carrier in the same sequence in which the devices are tested, and then correlating the test results with the device identifications. A prior art requirement of maintaining the carriers in the order in which they were tested is eliminated once the carriers have been thus identified. In a preferred embodiment the carrier body is provided with an array of perforations, the transmission of light through each perforation being blocked by a breakable membrane. Each carrier is coded by breaking a selected combination of its membranes to establish a unique binary identification code for each carrier.

Abstract: A carrier for a leadless integrated circuit chip has a cavity into which a chip is laterally inserted through an opening in a side wall of the carrier. A spring arm formed integrally with the carrier flexes backward in a recess to permit insertion of the chip, which has a plurality of electrical contact pads on its upper surface, and then bears against the chip under an internal spring bias to retain it within the cavity. Tabs at the upper corners of the cavity are positioned over the corners of the chip which are free of electrical contact pads, thereby preventing the chip from escaping while exposing the pads for both single and dual pin probing. The external configuration of the carrier conforms to industry standards so that the chip can be fully processed and tested without removing it from the carrier.

Abstract: An I.C. integrator circuit is provided with an active tuneable element by which a precise integrator time constant can be established, despite variations in the values of individual circuit components. A plurality of integrator circuits are connected in an overall frequency responsive circuit, each integrator circuit having a input transconductance stage, an output integrating stage, and an adjustable intermediate conditioning stage, the latter stage preferably comprising a Gilbert multiplier circuit. The time constant of each integrator circuit is controlled by the conditioning stage, which in turn is under the control of a bias circuit common to all of the integrator circuits. A desired net frequency response characteristic can be achieved by simple adjustments to the common bias circuit, despite normal tolerances and variations among individual integrator circuits.

Abstract: An automatic nulling circuit applicable to small leak detection in vacuum chambers. A pressure sensitive, variable impedance element is connected as one branch of a bridge circuit, another branch of which comprises an adjustable impedance circuit. The voltage across the two branches are normally balanced by means of an amplifier circuit which amplifies any differential between the branch voltages, and a feedback circuit between the amplifier output and the adjustable impedance element. The amplifier and feedback circuits, however, introduce a time lag such that the two branches are unbalanced, resulting in an amplified output, in response to a changing sensed pressure. A filter circuit removes the effects of long term pressure changes, whereby the nulling circuit produces an output only for short term transients in the rate of pressure change, such as those associted with small leak testing.

Abstract: A voltage control system for an induction motor, consisting of a SCR AC voltage controller with sensing and control circuitry, adjusts the motor voltage in response to the load torque demand, thereby minimizing the motor's magnetizing current and its associated losses. The motor displacement power factor angle, which is responsive to load torque, is sensed by directly sensing the motor voltage, deriving its fundamental or line frequency component, and phase-comparing that component with a similiarly derived fundamental component of the motor current. The resulting displacement power factor signal is amplified, together with a stability augmentation signal, to form a phase delay command signal for the AC controller. The stability augmentation signal, representative of the blocking voltage across the AC controller SCRs, is formed by rectifying the 180 Hz single phase sum of the three motor voltage signals.

Abstract: A manually operable calculator for optimizing aircraft fuel consumption during descent from an actual altitude to a target altitude/distance. Altitude and distance scales are provided which are alignable to determine an uncorrected fuel efficient distance to commence a descent from a given altitude to a target location, with separate scales being provided for different airspeeds. Wind and weight correction scales are also provided which give a distance correction based upon the aircraft's weight, prevailing wind conditions, and the difference between beginning and target altitudes. In the preferred embodiment a plurality of altitude scales are employed, each scale having thereon an altitude display which is proportioned in accordance with a respective air speed and given in terms of mach speed for altitudes above a mach speed/I.A.S. transition point, and in terms of I.A.S. below that point. In this embodiment a single, linear distance scale is employed.

Abstract: An improved start-up circuit is provided for self-biased circuits of the type connected to a supply voltage and having biasing currents stable at two operating points at which the biasing currents are either zero or nonzero in value when the supply voltage is nonzero and having sufficient regenerative feedback to raise the level of the biasing currents to the nonzero value when an initial current is provided to the circuit. The start-up circuit includes a resistive element which provides a current path from the supply voltage to the self-biased circuit and a transistor element, responsive to the current flow through the path for supplying an initial current to the self-biased circuit, whereupon the regenerative feedback causes the circuit to draw a current related to the biasing current through the current path as the biasing currents reach the nonzero operating point.

Abstract: A current control circuit which can be used to provide starting current during the build-up of an input voltage, and terminate the starting current when the input voltage has reached a predetermined level. The preferred embodiment employs three FETs and one bipolar transistor, located in a total of only two isolation pockets on an integrated circuit chip. The first FET, which is scaled to operate in its saturated region while the second FET is in its resistive region, transmits a current received from the second FET as an output starting current during the initial portion of the input voltage build-up. During this time the second FET holds the gate-source voltage of the first FET to a level less than its pinch-off voltage. The third FET has its gate and source terminals connected in parallel with the first FET, and its drain connected to the base of the bipolar transistor, which is also connected to shunt current away from the first FET when appropriately gated.

Abstract: A method and apparatus for detecting crossmodulation distortion on an optical sound track by detecting variations in the light transmitted through a predetermined area on the sound track, the predetermined area being selected such that its transmittance varies substantially only with the amount of crossmodulation distortion on the sound track. The predetermined area preferably has a dimension along the sound track which is a whole number multiple of, and substantially greater than, the wavelength of a high frequency test signal. Light is also transmitted through a second predetermined area on the sound track which clips the high frequency test signal, thereby providing a low frequency phase reference for determining the relative exposure of the film. In an alternate embodiment, the predetermined areas are divided into primary and secondary areas, mutually spaced by a distance which is out-of-phase with respect to the wavelength of a low frequency test signal.

Abstract: An improved analog track and hold circuit has a glitch-free output as the circuit switches between the tracking and the holding of an input analog signal. The circuit is of the type having a capacitor for storing an analog voltage, a transconductance amplifier for producing a charging current for the capacitor proportional to the analog voltage, a current switch for connecting and disconnecting the charging current for the capacitor, and an output circuit to buffer the capacitor voltage to the output. The improvement includes a diode array establishing first and second reference nodes across the capacitor. The diodes in the array clamp the first and second nodes to fixed incremental voltage values greater and lesser, respectively, than the capacitor voltage as the circuit tracks the analog voltage, and to fixed incremental voltage values lesser and greater, respectively, than the capacitor voltage, as the circuit holds the analog voltage.

Abstract: An electronic circuit simulates the direct current characteristics of the hybrid transformer portion of the telephone system call-handling equipment. The circuit is connected across a two-wire telephone subscriber loop and supplies a loop current that is proportional to the difference between a constant current and a reference current. The circuit contains a voltage sensing circuit which senses the voltage across the loop and transfers the sensed voltage across a reference resistor, thereby developing a reference current through the resistor which is proportional to the voltage across the subscriber loop. An integral current generator supplies a constant current to the circuit. An integral current subtractor, connected between the output of the voltage sensing circuit and the current generator subtracts the constant current from the reference current. The resulting current forms the input current to an integral current amplifier.

Abstract: A junction FET switching circuit and method in which the gate-source voltage of the switching FET is varied with changing temperature so as to maintain the FET channel resistance substantially constant over a selected temperature range. An offset is introduced to the gate-source voltage to permit adequate voltage variation over the temperature range.