Single Receiver System Research Articles

A Transmitter—Receiver System for Long-Range Capacitive Sensing Applications

Human occupancy detection and localization are important in a variety of smart building applications including building security, assisted living monitors, and energy-efficient heating ventilation and air cooling and lighting. Current implementation of such systems is limited by motion–sensor technologies, e.g., passive infrared (PIR) and ultrasonic sensors, which substitute as occupancy detectors but ultimately suffer from an inability to detect stationary objects. Capacitive sensing can detect stationary objects, but the technology has almost exclusively been developed for short-range human detection and localization, e.g., touch-screen human interfacing of smart devices. This paper presents a transmitter–receiver platform for research and development of capacitive sensing for long-range human occupancy detection and localization. During testing, the system revealed a detection range of 3.5 m, a typical room dimension in homes. Further, tests of a multitransmitter single-receiver system in a $3.2~\text {m} \times 3.2$ m space showed the system’s potential for occupant localization. Ultimately, this system represents an alternative to PIR and ultrasonic motion sensors, and has the potential to increase smart building system implementation.

Differential GPS supported navigation for a mobile robot

The objective of this work is the development of a low cost differential GPS system suited for mobile robotics applications which enhances positioning accuracy compared to a single receiver system. In order to keep costs minimal we used single frequency (L1) receivers, namely U-Blox AEK-4T. We adapted the GPS Toolkit (GPSTk) to work with single frequency (L1) observations in real-time. This allowed us to apply an already existing algorithm, originally intended for Precise Point Positioning (PPP) applications using a double frequency receiver. The core of this algorithm is a Kalman filter that processes code and carrier phase single differences. Carrier phase ambiguities are treated as real (float) values, we do not try to fix them to their correct integer values. In a static test with a baseline length of 11m, observations were collected for five minutes. The developed system achieved a horizontal RMS of 6.9cm. Furthermore we carried out a dynamic test where the rover drove around in a circle. Seven circles were driven in about five minutes. The system determined the circle's radius with an RMS error of 13.2cm.

Magnetic Resonant Coupling As a Potential Means for Wireless Power Transfer to Multiple Small Receivers

Wireless power transfer via magnetic resonant coupling is experimentally demonstrated in a system with a large source coil and either one or two small receivers. Resonance between source and load coils is achieved with lumped capacitors terminating the coils. A circuit model is developed to describe the system with a single receiver, and extended to describe the system with two receivers. With parameter values chosen to obtain good fits, the circuit models yield transfer frequency responses that are in good agreement with experimental measurements over a range of frequencies that span the resonance. Resonant frequency splitting is observed experimentally and described theoretically for the multiple receiver system. In the single receiver system at resonance, more than 50% of the power that is supplied by the actual source is delivered to the load. In a multiple receiver system, a means for tracking frequency shifts and continuously retuning the lumped capacitances that terminate each receiver coil so as to maximize efficiency is a key issue for future work.

Coherent acoustic communication in a tidal estuary with busy shipping traffic

High-rate acoustic communication experiments were conducted in a dynamic estuarine environment. Two current profilers deployed in a shipping lane were interfaced with acoustic modems, which modulated and transmitted the sensor readings every 200 s over a period of four days. QPSK modulation was employed at a raw data rate of 8 kbits on a 12-kHz carrier. Two 16-element hydrophone arrays, one horizontal and one vertical, were deployed near the shore. A multichannel decision-feedback equalizer was used to demodulate the modem signals received on both arrays. Long-term statistical analysis reveals the effects of the tidal cycle, subsea unit location, attenuation by the wake of passing vessels, and high levels of ship-generated noise on the fidelity of the communication links. The use of receiver arrays enables vast improvement in the overall reliability of data delivery compared with a single-receiver system, with performance depending strongly on array orientation. The vertical array offers the best performance overall, although the horizontal array proves more robust against shipping noise. Spatial coherence estimates, variation of array aperture, and inspection of array angular responses point to adaptive beamforming and coherent combining as the chief mechanisms of array gain.

Passive Optical Network Approach to Gigahertz-Clocked Multiuser Quantum Key Distribution

We present the application of quantum key distribution (QKD) technologies to fiber-based broad-band passive optical access networks. This application is based on our 850-nm wavelength gigahertz clock-rate single-receiver system, is compatible with existing telecommunications fiber and exploits a wavelength band not currently utilized in access networks. The developed QKD networks are capable of transmitting over distances consistent with the span of access links for metropolitan networks (10 km), at clock frequencies ranging up to 3 GHz

Resolution depths for some transmitter-receiver configurations

Equivalent dipole polarizability matrices and equivalent dipole location are a convenient way to interpret magnetic field data due to currents induced in isolated conductive objects. The uncertainties in polarizability estimates and in the equivalent dipole location provide a quantitative measure of the performance of different configurations of transmitters and receivers. In another paper, we estimate these uncertainties using a linearized inversion. For many systems, consisting of one or more rectangular loop transmitters and a number of dipole receivers, sited on a horizontal grid, equivalent dipole depth is determined to 10% accuracy to depths approximately 20% deeper than the depths at which polarizability matrix elements can be determined to the same precision. Systems that have a lower product of rms polarizability uncertainty and square root of their number of transmitter-receiver pairs are considered more effective for the number of transmitter-receiver pairs. Among the systems studied, a system with three orthogonal transmitter loops and a three-component receiver is the most effective, for objects shallower than 0.6 times the instrument siting grid spacing, yielding an rms polarizability uncertainty 0.04 times that of a single-transmitter single-receiver system. At intermediate depths, a system with two vertical component receivers on the diagonal of a square horizontal transmitter loop is most effective for its number of transmitter-receiver pairs, yielding an rms polarizability uncertainty 0.07 times that of a single receiver system. At depths greater than 2.5 times, the siting grid spacing a three-orthogonal loop transmitter with a single vertical component receiver is about the most effective for its number of transmitter-receiver pairs, yielding an rms polarizability uncertainty 0.08 times that of a single-transmitter system.

A new multibeam receiving equipment for the Valensole skywave HF radar: description and applications

The Valensole HF skywave radar, used since 1960 for remote sensing of geophysical media, has recently been upgraded by installation of a multireceiver system used with linear receiving arrays. The antenna elements are combined in subarrays and each of them is connected to a receiver. A new radar controller has been designed to allow for the automatic control of individual antenna elements. The purpose of this paper is to present this installation and the scientific goals which led the authors to build it. To illustrate the improved remote sensing capabilities of the multireceiver configuration, as compared to a single receiver system, the authors describe new results recently obtained in sea-state remote sensing applications and in ionospheric studies. This system has been built at a relatively low cost as allowed by a university budget.

An interference nulling algorithm for a single receiver phased array

An adaptive technique utilizing phase-only in interference suppression for a planar phased array is presented. No a priori knowledge of the interference direction is assumed, and the observed data are at the array output only: a single-receiver system. The sequential orthogonal search directions in the phase space are predetermined, and the algorithm is very simple computationally. Using the criterion of minimizing the interference power and a soft constraint in the look direction, for a 1369 element planar array and three interference sources, the required phase distribution is reached after approximately 220 time samples, or 11 ms (sampling rate 200 kHz) The convergence time varies approximately as a linear function of the number of interference sources, and is essentially independent of the array size. Some computed results are given. >

Radar System Errors in Polarization Diversity Measurements

Abstract The measurement capability of a polarization diversity radar is limited by several characteristics of the system and particularly by the performance of the antenna, which is characterized by the integrated cancellation ratio or integrated cross-polarization ratio. With reference to a transmitted or received signal of a desired polarization, these ratios describe the relative magnitude of the corresponding signal of opposite polarization generated as a result of antenna imperfections. In a single-receiver system operating with alternating horizontal and vertical polarization, the antenna performance tends to limit the accuracy with which the differential reflectivity can be measured. If the antenna pattern can be measured at orthogonal polarizations, then some of the bias introduced by antenna error can be removed from the resulting measurements. In this paper the magnitude of error of differential reflectivity relative to antenna performance is illustrated by calculations from theory. In a dual-r...

The development of single-receiver automatic adcock direction-finders for use in the frequency band 100–150 Mc/s

The paper describes the development of automatic direction-finders primarily intended for measuring the bearings of aircraft, on signals radiated in the frequency band 100–150 Mc/s. The basic system employs fixed elevated-H Adcock antennas and a single receiver, and, with the exception of the earliest model, all instruments give cathoderay oscillograph indication.An examination of the advantages and limitations of fixed*antenna automatic direction-finders employing two or more receivers leads to an account of the reasons for the adoption of a single-receiver system in the present development. The principles and evolution of this system are explained with reference to the original experimental models, whose performance is discussed.A naval direction-finder based on one of the experimental models is described in detail, and statistics are presented to show that the probable instrumental error varies from about 0.6–1.25 deg over the frequency band, after compensation for octantal error. Bearings can be measured on signals of field strength down to 7 μV/m or less.The paper concludes with a description of direction-finders for use on land. One of these, under current development, will be capable of unattended operation on two alternative frequency-channels, with bearing indication and full remote-control at points up to twenty miles distant.