Real-time locating system | EPFL Graph Search

Real-time locating systems (RTLS), also known as real-time tracking systems, are used to automatically identify and track the location of objects or people in real time, usually within a building or other contained area. Wireless RTLS tags are attached to objects or worn by people, and in most RTLS, fixed reference points receive wireless signals from tags to determine their location. Examples of real-time locating systems include tracking automobiles through an assembly line, locating pallets of merchandise in a warehouse, or finding medical equipment in a hospital. The physical layer of RTLS technology is often radio frequency (RF) communication. Some systems use optical (usually infrared) or acoustic (usually ultrasound) technology with, or in place of RF, RTLS tags. And fixed reference points can be transmitters, receivers, or both resulting in numerous possible technology combinations. RTLS are a form of local positioning system and do not usually refer to GPS or to mobile phon

Compensation des non-linéarités des systèmes haut-parleurs à pavillon

Delphine Bard

The assumptions of linearity and autonomy assumed in circuit theory are known to be respected only partially by electroacoustic transducers. In particular, the dynamics range of the latter is limited by the audible nonlinear effects that they are causing. In the domain of active noise control, the distortion products limit noise reduction performance. The present thesis work stems from characterization of these observations. We want to design a real-time system compensating the nonlinearities of electroacoustic devices. The first part of this report concerns the nonlinearity effects. It is shown that the use of classical characterization methods of an electroacoustic device (harmonic distortion, intermodulation, frequency difference ...) is limited. Hence, they can not be used to determine the nonlinearity laws themselves, but rather only their effects for arbitrary excitations. First, a method based on multitone harmonic excitations has been proposed and validated. It has been applied for the characterization of loudspeaker prototypes using several different technologies, which are used for active noise reduction in an aircraft turboreactor. The second part of this work addresses the elaboration and validation of a nonlinearity effect compensation method. This method is based on the description of the nonlinearities by the Volterra series. For this, we need to place an upstream system, characterized by the inverse nonlinearity law of the loudspeaker system. After having determined precisely the Volterra kernels of the system to be characterized, the kernels of the upstream compensation system are determined by assuming that their cascade obeys to a linear law. For this purpose, a kernel measurement method in the frequency domain has been developed, validated and tested. Since we are concerned with loudspeakers, we took their flying time into account. The compensation method has been validated by computing the simulated response of the compensation circuit. Resulting analog signals have then been applied to the loudspeaker. Measured performances fulfill the expectations. In the last part, the compensation method has been applied in a real-time Digital Signal Processing) DSP controller, which allowed to realize a demonstrator to the implemented for future industrial applications.

EPFL2005

Pediatric Size Swallowable Glass Pill for Digestive Motility Analysis

Catherine Dehollain, Onur Kazanç, Vincent Schlageter

A glass pill for digestive motility tracking with wireless communication is presented. The pill encapsulates three magnetic transmitter coils with a 125 kHz signal, the circuitry required to control the magnetic coil output and the battery. The system provides real time location of the pill inside the digestive tract of the patient using an external detector housed in a wearable jacket. The custom integrated circuit for this application reduces bill-of-materials (BOM) count and significant reduction in power consumption therefore resulting in further size reduction by adapting a smaller battery package. The outcome of the circuit integration enables the glass pill for pediatric use while providing a total pill diameter of 6 mm. The glass pill system operates continuously for 48 hours with a 1.55 V 8 mAh coin cell battery with an average power consumption of 250 microwatts.

IEEE2018

A Low Power Super-Regenerative Impulse Radio Ultra-Wideband Receiver in CMOS Technology

Communication systems have played a key role in changing our lives as such systems help to access remote data and to transfer it to the end user when requested. Intelligent nodes, which can process and transmit information placed in a given environment can provide localized data that might not be available through a public network such as the internet. As an example, nodes can provide dynamic data such as room temperature, chemical composition of air, or light intensity level. With the progress made in the semiconductor industry, such nodes have become compact, thereby making it easier to setup a cluster in a confined place. Often these nodes are to be placed in a remote location and hence the use of a cable to power up these devices might not be possible. Also, the use of cables makes the system bulky and heavy. For this reason battery-powered wireless sensor nodes are desirable. Such battery operated devices need to be energy efficient to avoid replacing the batteries often. Energy efficiency can be achieved by optimizing several parameters from the top (system level architecture) to the bottom (transistor level design). The thesis describes a receiver system design for Impulse-radio Ultra-Wideband (IR-UWB) signalling standard proposed in IEEE 802.11.4a for short range, low data rate communication system. The advantages of the IR-UWB signalling scheme over other existing standards and a comparison between various receiver architectures for IR-UWB standard using energy consumption as a metric is described. The main power consuming block in an IR-UWB receiver is identified to be the front-end amplifier structure as it needs to provide sufficient gain for proper operation of the subsequent stages. To reduce the power consumption of this amplifier, the super-regenerative architecture for IR-UWB system is proposed. It is shown in this work that since the super-regenerative receiver uses an amplifier with positive feedback, it can achieve high gain with a relatively low current, hence it can significantly reduce the power consumption. The super-regenerative receiver for the IR-UWB system is implemented in a 0.18 µm CMOS technology operating at 1.5 V, and the receiver energy consumption is 0.24 nJ/bit at a data rate of 10 Mbps. The receiver achieves a measured sensitivity of -66 and -61 dBm at 3.494 and 3.993 GHz, respectively, with a BER of 10-3. Finally, an automatic tuning circuitry based on a digital phase-locked loop architecture (DPLL) for super-regenerative receiver is proposed. The objective is to tune the receiver to either one of the sub-bands (3.494 or 3.993 GHz) as proposed in the IEEE 802.15.4a standard. Including the tuning circuitry helps to improve the receiver sensitivity, and also demonstrates the possibility for multi-band reception using such an architecture. The proposed DPLL is implemented in a 0.18 µm CMOS technology consuming 9.3 mW.

EPFL2010

A Low Power Super-Regenerative Impulse Radio Ultra-Wideband Receiver in CMOS Technology

EPFL2010

Compensation des non-linéarités des systèmes haut-parleurs à pavillon

Delphine Bard

EPFL2005