Broad Range Of Signals Research Articles

NaviSoC: High-Accuracy Low-Power GNSS SoC with an Integrated Application Processor

A dual-frequency all-in-one Global Navigation Satellite System (GNSS) receiver with a multi-core 32-bit RISC (reduced instruction set computing) application processor was integrated and manufactured as a System-on-Chip (SoC) in a 110 nm CMOS (complementary metal-oxide semiconductor) process. The GNSS RF (radio frequency) front-end with baseband navigation engine is able to receive, simultaneously, Galileo (European Global Satellite Navigation System) E1/E5ab, GPS (US Global Positioning System) L1/L1C/L5, BeiDou (Chinese Navigation Satellite System) B1/B2, GLONASS (GLObal NAvigation Satellite System of Russian Government) L1/L3/L5, QZSS (Quasi-Zenith Satellite System development by the Japanese government) L1/L5 and IRNSS (Indian Regional Navigation Satellite System) L5, as well as all SBAS (Satellite Based Augmentation System) signals. The ability of the GNSS to detect such a broad range of signals allows for high-accuracy positioning. The whole SoC (system-on-chip), which is connected to a small passive antenna, provides precise position, velocity and time or raw GNSS data for hybridization with the IMU (inertial measurement unit) without the need for an external application processor. Additionally, user application can be executed directly in the SoC. It works in the −40 to +105 °C temperature range with a 1.5 V supply. The assembled test-chip takes 100 pins in a QFN (quad-flat no-leads) package and needs only a quartz crystal for the on-chip reference clock driver and optional SAW (surface acoustic wave) filters. The radio performance for both wideband (52 MHz) channels centered at L1/E1 and L5/E5 is NF = 2.3 dB, G = 131 dB, with 121 dBc/Hz of phase noise @ 1 MHz offset from the carrier, consumes 35 mW and occupies a 4.5 mm2 silicon area. The SoC reported in the paper is the first ever dual-frequency single-chip GNSS receiver equipped with a multi-core application microcontroller integrated with embedded flash memory for the user application program.

Graph-Based Supervised Automatic Target Detection

In this paper, we propose a detection method based on data-driven target modeling, which implicitly handles variations in the target appearance. Given a training set of images of the target, our approach constructs models based on local neighborhoods within the training set. We present a new metric using these models and show that, by controlling the notion of locality within the training set, this metric is invariant to perturbations in the appearance of the target. Using this metric in a supervised graph framework, we construct a low-dimensional embedding of test images. Then, a detection score based on the embedding determines the presence of a target in each image. The method is applied to a data set of side-scan sonar images and achieves impressive results in the detection of sea mines. The proposed framework is general and can be applied to different target detection problems in a broad range of signals.

Cellular apoptosis and organ injury in sepsis: a review.

Cellular apoptosis and organ injury in sepsis: a review.

Managing Mitochondrial Mortality Messages

The proteins BAK and BAX are proapoptotic members of the "BH3-domain-only" family of proteins (so-called because they share with the BCL-2 family of proteins only the third of four BCL-2-homology domains). Wei et al. provide evidence that BAK and BAX are essential gatekeepers for apoptotic signals that act through the mitochondria. Signals from death receptors on the cell surface cause activation of tBID (another BH3-domain-only family member), which leads to release of cytochrome c from mitochondria and subsequent cell death. Cells that lacked BAK or BAX alone were still sensitive to tBID, but cells deficient in both proteins did not undergo tBID-induced apoptosis. A broad range of signals from the plasma membrane, nucleus, and endoplasmic reticulum required the presence of BAK or BAX and thus appear to promote cell death through signals that converge at the mitochondria. M. C. Wei, W.-X. Zong, E. H.-Y. Cheng, T. Lindsten, V. Panoutsakopoulou, A. J. Ross, K. A. Roth, G. R. MacGregor, C. B. Thompson, S. J. Korsmeyer, Proapoptotic BAX and BAK: A requisite gateway to mitochondrial dysfunction and death. Science 292 , 727-730 (2001). [Abstract] [Full Text]

Generalized coiflets with nonzero-centered vanishing moments

We show that imposing a certain number of vanishing moments on a scaling function (e.g., coiflets) leads to fairly small phase distortion on its associated filter bank in the neighborhood of DC. However, the phase distortion at the other frequencies can be much larger. We design a new class of real-valued, compactly supported, orthonormal, and nearly symmetric wavelets (we call them generalized coiflets) with a number of nonzero-centered vanishing moments equally distributed on scaling function and wavelet. Such a generalization of the original coiflets offers one more free parameter, the mean of the scaling function, in designing filter banks. Since this parameter uniquely characterizes the first several moments of the scaling function, it is related to the phase response of the lowpass filter at low frequencies. We search for the optimal parameter to minimize the maximum phase distortion of the filter bank over the lowpass half-band. Also, we are able to construct nearly odd-symmetric generalized coiflets, whose associated lowpass filters are surprisingly similar to those of some biorthogonal spline wavelets. These new wavelets can be useful in a broad range of signal and image processing applications because they provide a better tradeoff between the two desirable but conflicting properties of the compactly supported and real-valued wavelets, i.e., orthonormality versus symmetry, than the original coiflets.