Indoor Infrared Research Articles

Indoor Infrared Sensor Layout Optimization for Elderly Monitoring Based on Fused Genetic Gray Wolf Optimization (FGGWO) Algorithm.

With the increasing aging of the global population, the efficiency and accuracy of the elderly monitoring system become crucial. In this paper, a sensor layout optimization method, the Fusion Genetic Gray Wolf Optimization (FGGWO) algorithm, is proposed which utilizes the global search capability of Genetic Algorithm (GA) and the local search capability of Gray Wolf Optimization algorithm (GWO) to improve the efficiency and accuracy of the sensor layout in elderly monitoring systems. It does so by optimizing the indoor infrared sensor layout in the elderly monitoring system to improve the efficiency and coverage of the sensor layout in the elderly monitoring system. Test results show that the FGGWO algorithm is superior to the single optimization algorithm in monitoring coverage, accuracy, and system efficiency. In addition, the algorithm is able to effectively avoid the local optimum problem commonly found in traditional methods and to reduce the number of sensors used, while maintaining high monitoring accuracy. The flexibility and adaptability of the algorithm bode well for its potential application in a wide range of intelligent surveillance scenarios. Future research will explore how deep learning techniques can be integrated into the FGGWO algorithm to further enhance the system's adaptive and real-time response capabilities.

Comparative Study of Indoor Infrared Thermography Method to Estimate the Overall Thermal Resistance for Building Envelope Systems

Comparative Study of Indoor Infrared Thermography Method to Estimate the Overall Thermal Resistance for Building Envelope Systems

Improved outdoor thermography and processing of infrared images for defect detection in PV modules

Defect detection in photovoltaic (PV) modules and their impact assessment is important to enhance the PV system performance and reliability. To identify and analyze the defects, an improved outdoor infrared (IR) thermography scheme is presented in this study. The indoor (dark) and outdoor (illuminated) IR experiments are carried out on normal operating and defective PV modules. The indoor and outdoor measurements for normal operating modules are similar. However, the measurements for defective modules show difference i.e. the outdoor images show fewer or not at all defects in comparison to indoor images. Subsequent to this, outdoor imaging is carried out with our improved outdoor thermography scheme. This scheme is based on modulating the temperature of PV module through altering the electrical behavior of single cell. Therein, a PV cell is shaded in different fractions to attain different current conditions between open circuit and maximum power point, that causes temperature changes in series connected cells leading to different temperature conditions. The images obtained by this scheme provide clearer and detailed information about defects which is much similar to that given by indoor IR images. The severe and mild defective regions show temperature difference of more than 30° and 20° respectively in outdoor. The performance factor (PF) based on translated power output is also calculated for studied two modules that represents the quantitative impact of defects. The PF for PV module 1 and 2 is reduced from 97% to 31% and from 96% to 88% respectively with induction of defects. The PF values correlate with IR measurements of these modules. Furthermore, an image processing scheme comprising image filtering, color quantization and edge detection operations, is presented, that locate the edges of severe and mild defective regions in IR images.

Experimental Demonstration of Indoor Infrared Optical Wireless Communications With a Silicon Photonic Integrated Circuit

The optical wireless technology has great potential in realizing high-speed wireless communications in indoor applications, and the silicon photonics platform has been widely investigated to provide photonic integrations using advanced CMOS facilities. In this paper, the silicon integration of key beam steering function in high-speed infrared indoor optical wireless communication systems is proposed and investigated. The beam steering function is realized through edge couplers based silicon integrated optical phased array to achieve both wide operation bandwidth and high power efficiency. A 1 × 4 integrated phased array is designed and fabricated, and up to 12.5-Gb/s data transmission using the silicon integrated beam steering device through over 1.4 m free-space distance is experimentally demonstrated. Results show that error-free data transmission can be achieved with limited mobility provided to users, and the power penalty of the silicon integrated device is negligible. The outcomes successfully demonstrate the feasibility of using silicon photonic integrations in indoor optical wireless communication systems to realize compact and low-cost solutions.

Ultrahigh Throughput Indoor Infrared Wireless Communication System Enabled by a Cascaded Aperture Optical Receiver Fabricated on InP Membrane

Due to eye safety regulations, the allowable transmitted power in an optical wireless communication system is limited. Maximization of the optical power collected at the receiver is required in order to achieve the link power budget needed for maximum-speed data transfer. A large optical aperture at the receiver yields efficient power collection. Large-area top-illuminated photodiodes can on the one hand collect much light, but on the other hand inherently have a large capacitance and, thus, a reduced electrical bandwidth. To completely break this optical-electrical tradeoff, we propose a new class of optical receivers, i.e., cascaded aperture optical receivers. Such an optical receiver decouples the light collection function from the light detection one by using two separate apertures: the first function is done by surface grating coupler(s) feeding the received light into a waveguide, and the second one by an ultrahigh speed waveguide-coupled photodiode. These two apertures can be engineered independently to optimize the overall optical and electrical properties of the receiver. Empowered by an integrated cascaded aperture optical receiver fabricated on our InP membrane platform, we successfully demonstrated an indoor optical wireless communication system with a 200 Gb/s (5 λ × 40 Gb/s) capacity.

Comparison of Three Non-Imaging Angle-Diversity Receivers as Input Sensors of Nodes for Indoor Infrared Wireless Sensor Networks: Theory and Simulation.

In general, the use of angle-diversity receivers makes it possible to reduce the impact of ambient light noise, path loss and multipath distortion, in part by exploiting the fact that they often receive the desired signal from different directions. Angle-diversity detection can be performed using a composite receiver with multiple detector elements looking in different directions. These are called non-imaging angle-diversity receivers. In this paper, a comparison of three non-imaging angle-diversity receivers as input sensors of nodes for an indoor infrared (IR) wireless sensor network is presented. The receivers considered are the conventional angle-diversity receiver (CDR), the sectored angle-diversity receiver (SDR), and the self-orienting receiver (SOR), which have been proposed or studied by research groups in Spain. To this end, the effective signal-collection area of the three receivers is modelled and a Monte-Carlo-based ray-tracing algorithm is implemented which allows us to investigate the effect on the signal to noise ratio and main IR channel parameters, such as path loss and rms delay spread, of using the three receivers in conjunction with different combination techniques in IR links operating at low bit rates. Based on the results of the simulations, we show that the use of a conventional angle-diversity receiver in conjunction with the equal-gain combining technique provides the solution with the best signal to noise ratio, the lowest computational capacity and the lowest transmitted power requirements, which comprise the main limitations for sensor nodes in an indoor infrared wireless sensor network.

The Design of Indoor Infrared Alarm

This design uses the pyroelectric infrared detection technology, single-chip microcomputer control. Pyroelectric infrared sensor sensing the infrared thermal radiation (the body temperature is 37 degrees) of the invaders, converting it into a low frequency signal, passing to microcontroller through amplified circuit. Finally, it implements anti-theft through the alarm module.

Transmission Analysis of OFDM-Based Services Over Line-of-Sight Indoor Infrared Laser Wireless Links

Radio-on-free space optical (RoFSO) communication systems are gaining popularity because of their ability to transmit simultaneously multiple radio frequency signals comprised of various wireless services over FSO links using wavelength division multiplexing technology. We propose a new approach of use of the RoFSO technology for high-speed indoor communication systems and introduce an analytical model for the transmission of orthogonal frequency-division multiplexing-based signals over a line-of-sight link with diverged Gaussian beam. We have analyzed the laser safety restrictions for the proposed system and derived a closed-form bit-error probability, taking into account the ambient noise and laser diode nonlinear distortion. Simulation results are shown and the system performance is discussed.

LDPC-Coded OFDM for Heterogeneous Access Optical Networks

In this paper, we propose a heterogeneous optical access networking scenario, in which communication links between source and destination nodes are heterogeneous, composed of free-space optical, plastic optical fiber (POF), and indoor infrared (IR) links. To deal with bandwidth limitations of POF and IR links, a power-variable rate-adaptive low-density parity-check (LDPC)-coded orthogonal frequency division multiplexing (OFDM) scheme is used, while to deal with atmospheric turbulence, the spatial diversity is used. The rate-adaptive LDPC codes are designed using a modified progressive edge-growth (MPEG) algorithm. We show that with the proposed heterogeneous communication systems, we can deliver a high-speed optical signal (40 Gb/s and beyond) to an end-user.

Performance of Indoor Infrared Wireless CDMA Systems with Angle Diversity

Indoor infrared communication systems is one of the possible ways of offering data rates in excess of 100 Mbit/s without the need for wiring. Multiple users can share an infrared channel by code division-multiple access (CDMA) techniques. However, the CDMA system performance is limited by both background noise and co-channel interference. In this paper we study the use of angle diversity for mitigating the effects of the noise and interference. The system considered uses on-off shift keying modulation with multibeam transmitters and imaging receivers. The overall system performance for different diversity combining techniques is evaluated and compared to a system without diversity. Numerical results for a 2-user CDMA system indicate that signal to noise and interference ratio (SNIR) improvement (over systems with no diversity) of 5 dB is obtained for at least 50% of an ensemble of 10000 sample evaluations. The generalized selection combining (GSC)--a new diversity technique yet to be implemented for infrared systems--offers the best performance even with its reduced complexity.

BER performance of 166 Mbit∕s OOK diffuse indoor IR link employing wavelets and neural networks

The simulated bit error rate (BER) performance of a receiver structure employing wavelet analysis and neural networks in a diffuse indoor infrared (IR) environment operating at 166.6 Mbit/s is presented and discussed. The results are compared with the simulated performance of a zero forcing equaliser system for both baseband OOK-NRZ and OOK-RZ schemes.

Electronic tracking for wireless infrared communications

A high-speed wireless system (/spl ges/100 Mb/s) for indoor infrared (IR) communications via the line of sight is described and feasibility is shown in an experimental demonstrator. A diffuse link is used for connectivity, and tracked directed links are used for high-speed communications. The transmitter is made of a laser diode array in combination with multiple-beam forming optics. For the receiver (Rx), a wide-angle lens, and an avalanche photodiode array are used. For the diffuse link, the signals from all pixels in the array are combined. Pixels are selectively addressed to realize directed links. Fast electronic tracking of a directed link is possible by switching the signal path onto the right pixel in the array. Diffuse link, directed link, position detection, and tracking can be realized with one and the same transceiver hardware. A favorite system design is derived from constraints due to the IR channel, eye safety, lenses, photodetectors, and the overall system complexity. The experimental system shows some key features, namely 155-Mb/s wireless transmission over a distance of nearly 2 m with electronic tracking at an imaging IR Rx. Electronic tracking of IR links, thus, allows both high data rates and high capacity for wireless access in small office and home environments.

A study of transmitted pulse waveforms on indoor infrared wireless communications via diffuse links

The main problem of an indoor infrared (IR) wireless system via diffuse infrared link is bit error rate (BER) performance degradation due to intersymbol interference (ISI) induced by multipath distortion. In the previous study, only a rectangular pulse was employed as a transmitted pulse. However, multipath distortion tends to make the nondirected diffuse indoor IR channel have a low-pass frequency characteristic, and thus a rectangular pulse, whose spectrum has a form of sinc function, induces much ISI. In this paper, we analyze the BER performance of indoor IR wireless system via diffuse link employing different kinds of pulse waveforms, such as a Gaussian pulse and a raised cosine pulse, and consider the effect of ISI. Moreover, we analyze the BER performance employing a return-to-zero (RZ) pulse which has a guard interval in a slot. It is shown that the RZ Gaussian pulse is effective in mitigating the effect of ISI. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(9): 33–43, 2000

Wireless infrared factory network for hand‐held terminals

AbstractAn experimental wireless infrared network with ISDN compatibility is described. This factory network has been studied in a European project: “FCPN” (Factory Customer Premises Network). The architecture of the network is a cellular one. Infrared cells are connected together by a high‐speed optical fiber backbone. Hand‐held terminals communicate via an infrared (IR) channel based on a diffusion technique. The communication protocol on the infrared channel is based on the ISDN protocol with standard ISDN rate (2 x 64 kbits/s + 16 kbits/s)r Measurements of diffusion properties of standard construction materials are presented. These properties are in good agreement with the requirements of an indoor IR diffuse transmission. Architectural choices for the IR transceiver are discussed with special emphasis on consumption reduction for mobile‐terminals autonomy improvement. Key elements of the IR transceiver implementation are described. Experimental results for an IR diffuse channel are presented, showing the suitability of such a transmission technique for indoor hand‐held terminals. Performances of the system are described in term of Bit Error Rate measurements.