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.

The advanced camera for surveys nearby galaxy survey treasury. v. radial star formation history of ngc 300

Abstract: We present new Hubble Space Telescope (HST) observations of NGC 300 taken as part of the Advanced Camera for Surveys Nearby Galaxy Survey Treasury (ANGST). Individual stars are resolved in these images down to an absolute magnitude of M F814W = 1.0 (below the red clump). We determine the star formation history of the galaxy in six radial bins by comparing our observed color-magnitude diagrams (CMDs) with synthetic CMDs based on theoretical isochrones. We find that the stellar disk out to 5.4 kpc is primarily old, in contrast with the outwardly similar galaxy M33. We determine the scale length as a function of age and find evidence for inside-out growth of the stellar disk: the scale length has increased from 1.1 ± 0.1 kpc 10 Gyr ago to 1.3 ± 0.1 kpc at present, indicating a buildup in the fraction of young stars at larger radii. As the scale length of M33 has recently been shown to have increased much more dramatically with time, our results demonstrate that two galaxies with similar sizes and morphologies can have very different histories. With an N-body simulation of a galaxy designed to be similar to NGC 300, we determine that the effects of radial migration should be minimal. We trace the metallicity gradient as a function of time and find a present-day metallicity gradient consistent with that seen in previous studies. Consistent results are obtained from archival images covering the same radial extent but differing in placement and filter combination.

Software FMEA techniques

Abstract: Assessing the safety characteristics of software driven safety critical systems is problematic. The author has performed software FMEA on embedded automotive platforms for brakes, throttle, and steering with promising results. Use of software FMEA at a system and a detailed level has allowed visibility of software and hardware architectural approaches which assure safety of operation while minimizing the cost of safety critical embedded processor designs. Software FMEA has been referred to in the technical literature for more than fifteen years. Additionally, software FMEA has been recommended for evaluating critical systems in some standards, notably draft IEC 61508. Software FMEA is also provided for in the current drafts of SAE ARP 5580. However, techniques for applying software FMEA to systems during their design have been largely missing from the literature. Software FMEA has been applied to the assessment of safety critical real-time control systems embedded in military and automotive products. The paper is a follow on to and provides significant expansion to the software FMEA techniques originally described by the author in the 1993 RAMS paper "Validating The Safety Of Real-Time Control Systems Using FMEA".

Method and apparatus for modeling a smart antenna in a network planning tool

Abstract: A network planning tool (NPT) computer program is used to model characteristics of a wireless telephone network (10). The network contains a plurality of cells (12) which each include a plurality of sectors (16-18) disposed about a base station (13) that has a respective antenna for each sector. Techniques are provided for modeling smart antennas (131), including use of a switched-beam transmit and receive patterns with approximately random allocation among the beams of frequencies assigned to an associated sector. In the case of an adaptive beam-forming smart antenna, power levels for that antenna and a remote antenna operating at the same frequency are adjusted so as to increase a differential therebetween by an improvement value associated with the smart antenna. Potential uplink interference at a given base station is modeled by simulating operation of other base stations at an uplink frequency with a reduced power level. Potential interfering signals are discounted to the extent a smart antenna can intelligently reject a limited number of undesired signals.

Quaternary codes for pulsed radar

Abstract: A class of quaternary codes is described, and an algorithm for generating the codes is given. The codes have properties that make them useful for radar applications: 1) their auto-correlation consists of a single pulse, 2) their length can be any power of two, 3) each code can be paired with another code (its mate) of the same class in such a way that the crosscorrelation of mates is identically zero, 4) coded waveforms can be generated in a simple network the number of whose elements is proportional to the base-2 logarithm of the code length, and 5) the same network can be readily converted to a matched filter for the coded waveform.