Marcos Quilez

Initial Analysis of SAR From a Cell Phone Inside a Vehicle by Numerical Computation

The purpose of this paper is to analyze the influence of the metallic structures of a realistic car body frame on the specific absorption rate (SAR) produced by a cell phone when a complete human body model is placed at different locations inside the vehicle, and to identify the relevant parameters responsible for these changes. The modeling and analysis of the whole system was conducted by means of computer simulations based on the full wave finite-difference time-domain (FDTD) numerical method. The excitation considered was an 835 MHz lambda/2 dipole located as a hands-free communication device or as a hand-held portable system. We compared the SAR at different planes on the human model, placed inside the vehicle with respect to the free space situation. The presence of the car body frame significantly changes the SAR distributions, especially when the dipole is far from the body. Although the results are not conclusive on this point, this change in SAR distribution is not likely to produce an increase above the limits in current guidelines for partial body exposure, but may be significant for whole-body exposure. The most relevant change found was the change in the impedance of the dipole, affecting the radiated power. A complementary result from the electromagnetic computations performed is the change in the electromagnetic field distribution inside a vehicle when human bodies are present. The whole vehicle model has been optimized to provide accurate results for sources placed inside the vehicle, while keeping low requirements for computer storage and simulation time

Understanding electrosurgical unit perturbations in order to address hospital operating room electromagnetic compatibility

We analyze the radiated emissions from a low power electrosurgical unit(ESU). Measurements at a 3-meter distance are performed in order to find a suitable measurement setup intended to reproduce realistically the real working ESU behavior in a test lab. The broad-band and narrow-band characteristics of the perturbation are studied in order to address the other equipment immunity.

A Wireless Augmentative and Alternative Communication System for People With Speech Disabilities

An augmentative and alternative communication (AAC) device for people with speech disabilities is presented. This AAC system exhibits the advantages of two currently used systems: 1) usability of the communication boards and 2) natural oral communication of the electronic communicators. To improve comfort in use, robustness and versatility, the system is designed as two separate blocks linked by wireless communication via a wireless network of communication board sheets. The communication sheets, which are the interface with the user, are economical, simple to use, and scalable to adaptation of the number of symbols and the vocabulary of the individuals who use the system. The digital system (record/player system) controls the net, identifies the active sheets and the pushed symbols, and plays and records all sounds. This digital system can be easily replaced by other digital interfaces, such as computers, smartphones, or tablets, and can increase the function of the AAC with the possibility of using the Internet communication (emails and Skype, among others). The prototype has been evaluated in two special education schools, which are attended by children with severe motor disabilities with or without associated disorders and multi-deficiencies. Positive reviews from individuals who use the AAC system open the possibility of the systems use in both home and educational environments.

EMI from an automotive CAN bus

Electromagnetic radiated emissions from an automotive CAN bus are analyzed. This type of subsystems can produce interferences on electronic components or submodules, including radio receptors. Measurements inside and outside the car are performed. The control of the differential signal slope results in an easy way to reduce EMI at high frequencies. Finally, a set of near field measurements inside the car is presented.

A Near-Field Probe for In Situ EMI Measurements of Industrial Installations

In this paper, we present a frequency-selective probe intended to measure E and H fields simultaneously in the near-field region. The probe is implemented on a printed circuit board (PCB) that provides some advantages compared to those presented in previous works. The existing theoretical models are adapted in order to include the effect of both PCB trace and dielectric support. The probe is used for in situ electromagnetic compatibility (EMC) characterization of industrial installations, which offers valuable information that cannot be obtained by the usual EMC measurements.

Radiation pattern of a PCB based probe intended for near field measurements

In some situations, the OATS (open air test site) far field condition cannot be satisfied, and near field measurements must be performed. The EMI environment inside a car is one of these situations, where only near field probes can be used for measurement. We developed a near field probe that can measure the electric and magnetic fields simultaneously. The probe was built on a PCB (printed circuit board) along with the electronics needed to transmit the signals through an analog optical link. Calibration of the probe was performed in a TEM cell. The results for the sensitivity as a function of the frequency and the radiation pattern are presented.

Intelligent composting assisted by a wireless sensing network

Monitoring of the moisture and temperature of composting process is a key factor to obtain a quality product beyond the quality of raw materials. Current methodologies for monitoring these two parameters are time consuming for workers, sometimes not sufficiently reliable to help decision-making and thus are ignored in some cases. This article describes an advance on monitoring of composting process through a Wireless Sensor Network (WSN) that allows measurement of temperature and moisture in real time in multiple points of the composting material, the Compo-ball system. To implement such measurement capabilities on-line, a WSN composed of multiple sensor nodes was designed and implemented to provide the staff with an efficient monitoring composting management tool. After framing the problem, the objectives and characteristics of the WSN are briefly discussed and a short description of the hardware and software of the networks components are presented. Presentation and discussion of practical issues and results obtained with the WSN during a demonstration stage that took place in several composting sites concludes the paper.

An Electromagnetic Interference Reduction Check List for Unmanned Aircraft System

Unmanned Aircraft Systems may allow to y an uninhabited airplane or satellite with an autonomous control and monitored by the supervisor on ground. Safety y must be guarantee as the rest of airworthiness airplanes or space compliance satellites. The Unmanned Aircraft Systems were designed to operate in dangerous situations, like military missions bud nowadays, civil commercial applications come to be feasible due to the evolution in distributed embedded avionics systems. Dull and tedious surveillance applications are desired for this Unmanned Aerial Vehicles. A pico-satellite is a less than a kilogram mass satellite used mainly on educational projects for Low Earth Orbit (LEO) missions. Due to short time of live, down-link communications are implemented in a very high level of integration and non-gravity conditions in order to deliberate the scienti c information before drop down to the atmosphere. Both, Unmanned Aerial Vehicles and pico-satellites present same electromagnetic compatibility problems. This high level of integration, some times brings an electromagnetic interference situation between embedded systems especially because the near eld of emissions are present in the Unmanned Aircraft System reduced con ned avionics bay. Emission, Susceptibility, and Path are playing in this environment. That was our experience with an UAV Megastar model. The near earth antenna re ection produced a multi-path coupling. The radio transmitter antenna makes unserviceable the entire ight control surfaces, situation that makes an unsafe y. Also, during the pico-satellite design we must take in consideration the near eld for a good electromagnetic compatibility requirements. This paper is an electromagnetic compatibility study for Unmanned Aircraft System. We will show a case of real electromagnetic interference in our particular UAV Megastar, and how was solved. We will present some good EMC practices in order to translate the distributed embedded avionics platform to our new UAV Shadow MK1. Also we present our pico-satellite design and many examples of solutions of electromagnetic interferences. Finally we will consider an electromagnetic interference reduction check list applied on Unmanned Aircraft System where avionics bay con guration may change depending on the requirements of the mission.

NIBLUM: non-invasive bluetooth mouse for wheelchair users

Being autonomous is one of the biggest challenges for many people with disabilities. While wheelchairs enable individuals to move freely, computers allow them to communicate, work, etc. by their own. In many cases both devices are controlled by two different interfaces of the same kind -two joysticks- and people need the assistance of a second person to switch between them. In this article we describe how any person that drives a wheelchair using a joystick, can control the pointer of any computer using the same driving joystick and without being helped by anyone. This device, NIBLUM, uses Bluetooth to get a wireless and transparent connection with the computer. As it is not necessary to modify the wheelchair, its manufacturers guaranty is not voided, something essential to enable NIBLUMs real usage

Bulk current injection test uncertainty assessment

Modern automobiles incorporate increasing amount of electronic systems, many with vehicle safety concerns, working in a harsh electromagnetic environment. The vehicle components immunity to electromagnetic interference is fundamental and is covered by international standards like ISO 11452-x and SAE J1113-x series for automotive EMC immunity testing. Also, each automobile manufacturer has its own EMC immunity requirements covering the different types of disturbances: radiated, conducted and ESD. Usually, the uncertainty related to the determination of the applied immunity level is not considered in the automotive EMC standards, but it is an important issue in test reliability and repeatability. We describe a methodology for uncertainty assessment in EMC immunity tests particularizing it on the bulk current injection test.