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.

Fault tolerant distributed control system

Abstract: A fault tolerant distributed intelligence control system for sensing and control across fault tolerant fiber optic communication media interconnecting a plurality of intelligent nodes. Each intelligent node comprises a digital control and communication processor (DCCP) operating autonomously in relation to DCCPs at other nodes, and a transceiver for interfacing with the communication media. The fiber optic communication media comprises bi-directional serial data buses. The combination provides a low cost highly reliable distributed control system particularly applicable to primary and secondary aircraft control systems, as well as to other vehicle and control systems.

Bounds on Compactness for Low-Mass X-Ray Binary Neutron Stars from X-Ray Burst Oscillations

Abstract: We have modeled X-ray burst oscillations observed with the Rossi X-Ray Timing Explorer from two low-mass X-ray binaries (LMXB): 4U 1636-53 with a frequency of 580 Hz and 4U 1728-34 at a frequency of 363 Hz. We have computed least-squares fits to the oscillations observed during the rising phase of bursts using a model that includes emission from either a single circular hot spot or a pair of circular antipodal hot spots on the surface of a neutron star. We model the spreading of the thermonuclear hot spots by assuming that the hot spot angular size grows linearly with time. We calculate the flux as a function of rotational phase from the hot spots and take into account photon deflection in the relativistic gravitational field of the neutron star, assuming the exterior spacetime is the Schwarzschild metric. We find acceptable fits with our model in a χ2 sense and use these to place constraints on the compactness of the neutron stars in these sources. For 4U 1636-53, in which detection of a 290 Hz subharmonic supports the two-spot model, we find that the compactness (i.e., mass/radius ratio) is constrained to be M/R < 0.163 at 90% confidence (G = c = 1). This requires a relatively stiff equation of state (EOS) for the stellar interior. For example, if the neutron star has a mass of 1.4 M☉, then its radius must be greater than 12.8 km. Fits using a single hot spot model are not as highly constraining. We discuss the implications of our findings for recent efforts to calculate the EOS of dense nucleon matter and the structure of neutron stars.

Long-wavelength 640/spl times/486 GaAs-AlGaAs quantum well infrared photodetector snap-shot camera

Abstract: A 9-/spl mu/m cutoff 640/spl times/486 snap-shot quantum well infrared photodetector (QWIP) camera has been demonstrated. The performance of this QWIP camera is reported including indoor and outdoor imaging. The noise equivalent differential temperature (NE/spl Delta/T) of 36 mK has been achieved at 300 K background with f/2 optics. This is in good agreement with expected focal plane array sensitivity due to the practical limitations on charge handling capacity of the multiplexer, read noise, bias voltage, and operating temperature.

Radio frequency energy launcher

Abstract: A radio frequency energy launcher providing efficient energy transfer between a coaxial transmission line having spaced inner and outer conductors and a microstrip transmission line comprising a first relatively thin strip conductor and second wider ground plane conductor separated by a dielectric substrate. The launcher includes a conductive housing providing a passageway forming an outer conductor and a spaced inner conductor angled with respect to the passageway outer conductor forming wall and a surface of the substrate. Such angled inner conductor having an end region connected to the coaxial transmission line and having the other end interconnected to the thin strip conductor of the microstrip transmission line. The inner conductor is angled acutely and/or obliquely to such housing wall and a surface of dielectric substrate. The launcher structure is mounted on an extension of the wider ground plane conductor of the microstrip transmission line thus permitting the utilization of a substantially thinner ground plane conductor member while assuring firm mechanical contact with the thin strip conductor microstrip transmission line. The angularly orientated launcher provides for maintaining constant impedance in the transformation of electromagnetic energy fields from a concentric coaxial line distribution to a concentrated eccentric configuration for microstrip line transmission.

Overhead imagery research data set — an annotated data library & tools to aid in the development of computer vision algorithms

Abstract: When failures occur in machine object recognition algorithms, researchers may have limited information on the root causes of the failure. For example, did the algorithm fail to detect a target due to occlusion, shadow, contrast, or some other known computer vision shortcoming? The Overhead Imagery Research Data Set (OIRDS) project will help advance the state of the art in image processing and computer vision by providing an open-access, annotated overhead imagery library that will allow researchers to break down algorithm performance by image and target attributes. The OIRDS project has produced a data set with almost 1,000 labeled images suitable for developing automated vehicle detection algorithms. These images contain approximately 1,800 labeled targets. For each target, the OIRDS provides over 30 annotations and over 60 statistics that describe the target within the context of the image.