Array Processing in Atrial Fibrillation: Application of different signal models and LAT estimation techniques

Atrial fibrillation (AF) is the most commonly occurring arrhythmia in clinical practice and can have a significant impact on the current and future wellbeing of the patient. By placing an unipolar sensor array directly on the epicardium during an open-heart surgery to measure the electrical activity of the atrium, more insight about this disease...

Sensor Selection for Angle of Arrival Estimation Based on the Two-Target Cramér-Rao Bound

Sensor selection is a useful method to help reduce data throughput, as well as computational, power, and hardware requirements, while still maintaining acceptable performance. Although minimizing the Cramér-Rao bound has been adopted previously for sparse sensing, it did not consider multiple targets and unknown source models. In this work, we...

A bird's-eye view on infrasound: High-resolution methods to unravel the ambient microbarom wavefield

Cryoseismic Event Analysis on Distributed Strain Recordings Leveraging Statistical Learning Methods

In the summer of 2020, ETH researchers installed a 9 km long fiber-optic cable on the Rhonegletscher (Switzerland), covering the whole glacier extent from accumulation to ablation zone.<br/>The fiber was then interrogated with a DAS system, turning it into a distributed seismic antenna. The DAS system recorded continuously for one month on more...

Conversations between the Earth and Atmosphere: A study on the seismo-acoustic wavefield

The study of seismo-acoustic events is by no means new. Observations of earthquake-induced infrasound signals are dated back to the 1950s. However, the relative recent deployment of the International Monitoring System (IMS) by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) provided world coverage for such signals. The continuous...

A 77-GHz FMCW MIMO Radar Employing a Non-Uniform 2D Antenna Array and Substrate Integrated Waveguides

In state-of-the-art frequency-modulated continuous-wave (FMCW) multiple-input multiple-output (MIMO) radar systems, antennas are usually designed based on microstrip technology. They are arranged in uniform arrays such that the synthesized virtual array maximizes the angular resolution. This paper presents the design of a 77-GHz FMCW MIMO...

A Three-Dimensional Array for the Study of Infrasound Propagation Through the Atmospheric Boundary Layer

The Royal Netherlands Meteorological Institute (KNMI) operates a three-dimensional microbarometer array at the Cabauw Experimental Site for Atmospheric Research observatory. The array consists of five microbarometers on a meteorological tower up to an altitude of 200 m. Ten ground-based microbarometers surround the tower with an array aperture...

Uniaxial Acoustic Vector Sensors for direction-of-arrival estimation

In this paper, a specific reduced-channel Acoustic Vector Sensor (AVS) is proposed comprising one omni-directional microphone and only one particle velocity transducer, such that it can have an arbitrary orientation. Such a reduced transducer configuration is referred to as a Uniaxial AVS (U-AVS). The DOA performance of an array of U-AVSs is...

Information distances for radar resolution analysis

A stochastic approach to resolution based on information distances computed from the geometry of data models which is characterized by the Fisher information is explored. Stochastic resolution includes probability of resolution and signal-to-noise ratio (SNR). The probability of resolution is assessed from a hypothesis test by exploiting...

Bidirectional infrasonic ducts associated with sudden stratospheric warming events

In January 2011, the state of the polar vortex in the midlatitudes changed significantly due to a minor sudden stratospheric warming event. As a result, a bidirectional duct for infrasound propagation developed in the middle atmosphere that persisted for 2 weeks. The ducts were due to two zonal wind jets, one between 30 and 50 km and the other...

Fish-Eye Observing with Phased Array Radio Telescopes

The radio astronomical community is currently developing and building several new radio telescopes based on phased array technology. These telescopes provide a large field-of-view, that may in principle span a full hemisphere. This makes calibration and imaging very challenging tasks due to the complex source structures and direction dependent...

Spatial filtering of interfering signals at the initial Low Frequency Array (LOFAR) phased array test station

The Low Frequency Array (LOFAR) is a radio telescope currently being designed. Its targeted observational frequency window lies in the range of 10–250 MHz. In frequency bands in which there is interference, the sensitivity of LOFAR can be enhanced by interference mitigation techniques. In this paper we demonstrate spatial filtering capabilities...