Jet Propulsion Laboratory

About: Jet Propulsion Laboratory is a facility organization based out in La Cañada Flintridge, California, United States. It is known for research contribution in the topics: Mars Exploration Program & Telescope. The organization has 8801 authors who have published 14333 publications receiving 548163 citations. The organization is also known as: JPL & NASA JPL.

New exponential bounds and approximations for the computation of error probability in fading channels

Abstract: We present new exponential bounds for the Gaussian Q function (one- and two-dimensional) and its inverse, and for M-ary phase-shift-keying (MPSK), M-ary differential phase-shift-keying (MDPSK) error probabilities over additive white Gaussian noise channels. More precisely, the new bounds are in the form of the sum of exponential functions that, in the limit, approach the exact value. Then, a quite accurate and simple approximate expression given by the sum of two exponential functions is reported. The results are applied to the general problem of evaluating the average error probability in fading channels. Some examples of applications are also presented for the computation of the pairwise error probability of space-time codes and the average error probability of MPSK and MDPSK in fading channels.

The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)

Abstract: Aims. This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods. The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results. After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations.

The HITRAN molecular spectroscopic database and HAWKS (HITRAN atmospheric workstation)

Abstract: Nineteen ninety-eight marks the 25th anniversary of the release of the first HITRAN database. HITRAN is recognized as the international standard of the fundamental spectroscopic parameters for diverse atmospheric and laboratory transmission and radiance calculations. There have been periodic editions of HITRAN over the past decades as the database has been expanded and improved with respect to the molecular species and spectral range covered, the number of parameters included, and the accuracy of this information. The 1996 edition not only includes the customary line-by-line transition parameters familiar to HITRAN users, but also cross-section data, aerosol indices of refraction, software to filter and manipulate the data, and documentation. This paper describes the data and features that have been added or replaced since the previous edition of HITRAN. We also cite instances of critical data that is forthcoming. A new release is planned for 1998.

Genome sequence of the dissimilatory metal ion-reducing bacterium Shewanella oneidensis.

Abstract: Shewanella oneidensis is an important model organism for bioremediation studies because of its diverse respiratory capabilities, conferred in part by multicomponent, branched electron transport systems. Here we report the sequencing of the S. oneidensis genome, which consists of a 4,969,803-base pair circular chromosome with 4,758 predicted protein-encoding open reading frames (CDS) and a 161,613-base pair plasmid with 173 CDSs. We identified the first Shewanella lambda-like phage, providing a potential tool for further genome engineering. Genome analysis revealed 39 c-type cytochromes, including 32 previously unidentified in S. oneidensis, and a novel periplasmic [Fe] hydrogenase, which are integral members of the electron transport system. This genome sequence represents a critical step in the elucidation of the pathways for reduction (and bioremediation) of pollutants such as uranium (U) and chromium (Cr), and offers a starting point for defining this organism's complex electron transport systems and metal ion-reducing capabilities.