Raytheon

About: Raytheon is a company organization based out in Waltham, Massachusetts, United States. It is known for research contribution in the topics: Signal & Antenna (radio). The organization has 15290 authors who have published 18973 publications receiving 300052 citations.

Asynchronous data clock generator

Abstract: A circuit and method for generating a substantially smooth clock for clocking asynchronous data to a user device. Incoming asynchronous data is stored in an elastic buffer such as a first-in first-out memory. Periodically, an output identifiable bit is read into the memory and a multibit digital signal corresponding to the number of output clock pulses for it to be read out is determined. This signal, which corresponds to the occupancy of the first-in first-out memory, is used to generate an analog voltage which controls a voltage controlled oscillator that provides the substantially smooth clock for reading data out of the first-in first-out memory. The control loop causes the long term rate of the smooth clock to be substantially equal to the incoming asynchronous data rate.

Focal plane readout unit cell background suppression circuit and method

Abstract: A background suppression technique uses well-controlled and repeatable charge skimming operations to increase the charge capacities of the integration capacitors of integrated focal plane readout unit cells. A MOSFET (Q1) is connected to an integration capacitor (C int ) from which the quantity of stored charge is to be reduced. During each photocurrent integration period, the MOSFET is driven with a "skimming pulse" (V sk ) to draw charge from the capacitor. The skimming pulse is substantially shorter than an integration period, reducing the amount of noise contributed by the MOSFET's noise mechanisms, and has an amplitude great enough to drive the MOSFET into its strong inversion mode, making the quantity of the removed charge relatively insensitive to variations in MOSFET threshold voltage. The charge skimming pulse is arranged to reduce the charge on the capacitor almost, but not quite, to zero, so that the entire integration period remains utilized.

Plasma panel display device including spheroidal glass shells

Abstract: A plasma panel display device wherein a plasma forming gas is encapsulated in clear glass spheres which are sandwiched between two glass or plastic panels having transparent electrodes thereon. In some embodiments, the type of gas filling some of the spheres is varied to provide a multicolor display panel. A method for filling the small glass spheres with the preferred gas is also described.

Microwave phase conjugation using antenna arrays

Abstract: A technique has been developed and tested for achieving phase conjugation in the microwave and millimeter-wave regime. The effective nonlinearity required for this phase-conjugation process is provided by electronic mixing elements feeding an array of antennas. Using these balanced mixing circuits in conjunction with a one-dimensional array antenna, we have demonstrated two-dimensional free-space phase conjugation at 10.24 GHz. A critical factor of this technique is the delivery of a 2/spl omega/ pump signal to each array element with the same phase. Two types of interconnects, electrical and a more versatile optical technique, have been implemented to distribute the pump signal in our demonstrations. In both systems, two-dimensional free-space phase conjugation was observed and verified by directly measuring the electric-field amplitude and phase distribution under various conditions. The electric-field wave-fronts exhibited retro-directivity and the auto-correction characteristics of phase conjugation. Furthermore, these experiments have shown amplified conjugate-wave power up to ten times of that of the incoming wave. This amplifying ability demonstrates the potential of such arrays to be used in novel communications applications.

Observational constraints on red and blue helium burning sequences

Abstract: We derive the optical luminosity, colors, and ratios of the blue and red helium burning (HeB) stellar populations from archival Hubble Space Telescope observations of nineteen starburst dwarf galaxies and compare them with theoretical isochrones from Padova stellar evolution models across metallicities from Z = 0.001 to 0.009. We find that the observational data and the theoretical isochrones for both blue and red HeB populations overlap in optical luminosities and colors and the observed and predicted blue to red HeB ratios agree for stars older than 50 Myr over the time bins studied. These findings confirm the usefulness of applying isochrones to interpret observations of HeB populations. However, there are significant differences, especially for the red HeB population. Specifically, we find (1) offsets in color between the observations and theoretical isochrones of order 0.15 mag (0.5 mag) for the blue (red) HeB populations brighter than MV ~ –4 mag, which cannot be solely due to differential extinction; (2) blue HeB stars fainter than MV ~ –3 mag are bluer than predicted; (3) the slope of the red HeB sequence is shallower than predicted by a factor of ~3; and (4) the models overpredict the ratio of the most luminous blue to red HeB stars corresponding to ages 50 Myr. Additionally, we find that for the more metal-rich galaxies in our sample (Z 0.5 Z ☉), the red HeB stars overlap with the red giant branch stars in the color-magnitude diagrams, thus reducing their usefulness as indicators of star formation for ages 100 Myr.