Radio | EPFL Graph Search

Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 3,000 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by another antenna connected to a radio receiver. Radio is widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing, and other applications. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking, and satellite communication, among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft and missiles

A Fully Integrated Counter Flow Energy Reservoir for Peak Power Delivery in Small Form-Factor Sensor Systems

Yao Shi

We present a fully integrated energy reservoir unit using a counter flow method for peak power delivery in space-constrained sensor systems. Recent advances in circuits have enabled significant reduction in the size of wireless systems such as implantable biomedical devices. As a consequence, the batteries integrated in these systems have also shrunk, resulting in high internal resistances (~10 kQ). However, the peak current requirement of power-hungry components such as radios remains in the milliwatt range and hence cannot directly be supplied from the battery. Therefore, an energy reservoir with high output power but small size is required. We present an efficient energy reservoir that dynamically reconfigures a storage capacitor array using a so-called counter flow approach. By creating a voltage gradient on capacitor arrays and moving the capacitors along the slope of the gradient, the supply voltage can be maintained while the energy stored in the reservoir is delivered efficiently to the load. The counter flow energy reservoir delivers 65% of stored energy before recharging is needed which allows up to a 12× reduction in overall capacitor size compared with our implementation of the previous method. The design supplies up to 13.6-mW output power for 1 μs. We demonstrate the proposed concept with a pulsed radio, showing an 11.5× increase in pulse length compared with the previous method.

IEEE2017

Hybridation MEMS/UWB pour la navigation pédestre intra-muros

Valérie Jeanne Thérèse Renaudin-Schouler

Facing the expansion of geolocation needs, illustrated by the GALILEO European project, the growth of Location Based Services (LBS) and the need to identify the location of emergency mobile phone calls in Europe (standard E112), the research on localization techniques is booming. This thesis focuses on indoor pedestrian navigation and investigates a localization solution based on micro-electromechanical systems (MEMS) and ultra-wideband waves (UWB). MEMS based localization estimates the current location from a previously determined position using on-board low-cost inertial embedded sensors. Unfortunately, the performances of these autonomous systems are affected by large errors (typical of these sensors). In fact standalone solutions drift rapidly with time. Impulse-Radio UWB (IR-UWB) Times Of Arrival (TOA) are often used for localization purposes. This network based technology uses sensor networks, mainly attached to the infrastructure of the building to estimate the location of the transmitter with decimetre accuracy in ideal scenarii. However the indoor environment is hostile for radio propagation. Full of artificial obstacles, electromagnetic waves are disturbed and radiolocation performances are reduced. Construction materials also affect the magnetic field used to estimate the pedestrian's walking direction. In this context, the hybridization of these two complementary and uncorrelated technologies is promising. The study of the movement pattern of a pedestrian walking indoors induces two main outcomes on localization techniques. Firstly, random pedestrian movements complicate MEMS signal processing. Secondly, when the transmitter is worn by the user, for example around the neck, IR-UWB that propagates through the human body can hardly contribute to the localization. Optimal data fusion filters that hybridize a large set of observations : Angles Of Arrival (AOA), Time Differences Of Arrival (TDOA), accelerations, angular velocities and magnetic field measurements are presented. The coupling of UWB and MEMS data relies on an Extended Kalman Filter (EKF) complemented with specific procedures. Loose integration and tight integration are considered. Outlier detection processes within the radio data enrich the EKF. The most remarkable process is based on the RANSAC paradigm and employs the physical constraints of the pedestrian's walk described by biomechanics. In some cases, it enables the processing of reflected radio signals. A user equipped with a MEMS module and an UWB transceiver walked in the premises of the EPFL, following nine independent paths, for a total length of 380 m. The benefit of the MEMS/UWB hybridization filters are evaluated based on this experiment. The tight integration outperforms the loose coupling and enables indoor pedestrian localization with a one metre accuracy.

EPFL2009

The infrared-radio correlation of star-forming galaxies is strongly M-star-dependent but nearly redshift-invariant since z similar to 4

Shan Jin, Mark Thomas Sargent

Over the past decade, several works have used the ratio between total (rest 8-1000 mu m) infrared and radio (rest 1.4 GHz) luminosity in star-forming galaxies (q(IR)), often referred to as the infrared-radio correlation (IRRC), to calibrate the radio emission as a star formation rate (SFR) indicator. Previous studies constrained the evolution of q(IR) with redshift, finding a mild but significant decline that is yet to be understood. Here, for the first time, we calibrate q(IR) as a function of both stellar mass (M-star) and redshift, starting from an M-star-selected sample of > 400 000 star-forming galaxies in the COSMOS field, identified via (NUV-r)/(r-J) colours, at redshifts of 0.1

2021

Hybridation MEMS/UWB pour la navigation pédestre intra-muros

Valérie Jeanne Thérèse Renaudin-Schouler

EPFL2009