Radio Frequency Monitoring Research Articles

Comparison of mathematical and experimental studies of the radio technical characteristics of an acousto-optoelectronic spectrum analyzer for RF monitoring devices

Formulation of the problem. To analyze radio frequency monitoring systems and complexes that can operate in a wide frequency band with high performance parameters, devices such as acousto-optical spectrum analyzers (AOS) are used. This class of devices has several types of implementation. The objective of this article is to increase efficiency in the development of acousto-optoelectronic devices in radio frequency monitoring systems. Target. Based on theoretical and experimental studies, it is necessary to determine which version of the acousto-optical spectrum analyzer will ensure the operation of radio frequency monitoring tools with the best values of radio frequency characteristics, such as dynamic range and signal-to-noise ratio. Results. A calculation of the dynamic range of an acousto-optical spectrum analyzer is presented, as well as a comparative analysis of several acousto-optical spectrum analyzers (an acousto-optic spectrum analyzer with time integration and an acousto-optic spectrum analyzer with spatio-temporal integration) to determine the most effective type of device for radio frequency monitoring systems. Practical significance. The use of the selected design of an acousto-optical spectrum analyzer will make it possible to replace other devices and replace less efficient analogues of the device, which will improve the operation of radio frequency monitoring systems and complexes.

High-speed RF spectral analysis using a Rayleigh backscattering speckle spectrometer.

Persistent wideband radio frequency (RF) surveillance and spectral analysis is increasingly important, driven by the proliferation of wireless communication and RADAR technology. However, conventional electronic approaches are limited by the ∼1 GHz bandwidth of real-time analog-to-digital converters (ADCs). While faster ADCs exist, high data rates prohibit continuous operation, limiting these approaches to acquiring short snapshots of the RF spectrum. In this work, we introduce an optical RF spectrum analyzer designed for continuous, wideband operation. Our approach encodes the RF spectrum as sidebands on an optical carrier and relies on a speckle spectrometer to measure these sidebands. To achieve the resolution and update rate required for RF analysis, we use Rayleigh backscattering in single-mode fiber to rapidly generate wavelength-dependent speckle patterns with MHz-level spectral correlation. We also introduce a dual-resolution scheme to mitigate the trade-off between resolution, bandwidth, and measurement rate. This optimized spectrometer design enables continuous, wideband (15 GHz) RF spectral analysis with MHz-level resolution and a fast update rate of 385 kHz. The entire system is constructed using fiber-coupled off-the-shelf-components, providing a powerful new approach for wideband RF detection and monitoring.

Lessons Learned from a Distributed RF-EMF Sensor Network.

In an increasingly wireless world, spatiotemporal monitoring of the exposure to environmental radiofrequency (RF) electromagnetic fields (EMF) is crucial to appease public uncertainty and anxiety about RF-EMF. However, although the advent of smart city infrastructures allows for dense networks of distributed sensors, the costs of accurate RF sensors remain high, and dedicated RF monitoring networks remain rare. This paper describes a comprehensive study comprising the design of a low-cost RF-EMF sensor node capable of monitoring four frequency bands used by wireless telecommunications with an unparalleled temporal resolution, its application in a small-scale distributed sensor network consisting of both fixed (on building façades) and mobile sensor nodes (on postal vans), and the subsequent analysis of over a year of data between January 2019 and May 2020, during which slightly less than 10 million samples were collected. From the fixed nodes’ results, the potential errors were determined that are induced when sampling at lower speeds (e.g., one sample per 15 min) and measuring for shorter periods of time (e.g., a few weeks), as well as an adequate resolution (30 min) for diurnal and weekly temporal profiles which sufficiently preserves short-term variations. Furthermore, based on the correlation between the sensors, an adequate density of 100 sensor nodes per km2 was deduced for future networks. Finally, the mobile sensor nodes were used to identify potential RF-EMF exposure hotspots in a previously unattainable area of more than 60 km2. In summary, through the analysis of a small number of RF-EMF sensor nodes (both fixed and mobile) in an urban area, this study offers invaluable insights applicable to future designs and deployments of distributed RF-EMF sensor networks.

BEAM ANTENNA FOR CONTROLLING WIRELESS 5 GHZ DATA TRANSMISSION NETWORKS

Recently, there has been an intensive development of wireless data networks in the 2.4 and 5 GHz ranges, or Wi-Fi. The popularity of these networks is mainly due to the transmission of multimedia information. Existing standards and data protocols for these networks ensure their smooth and high-performance operation in «ideal conditions». In fact, in cities and densely populated centers with a significant amount of such equipment as well as lack of backup channels, there is radio frequency interference. These interferences are caused by the impact of one piece of equipment on another when it is impossible to adjust by switching to backup channels. Due to the interference, the data transmission speed is reduced, and in some complex cases, the data transmission is stopped completely. This negative phenomenon especially affects the 5 GHz range, in which the signal range is less than that for the 2 GHz range. To assess the quality of wireless data transmission networks, the following characteristics are monitored: the average emission frequency and the emission bandwidth. When these characteristics go beyond the standard values, there are interferences detected by the radio frequency monitoring bodies. Monitoring is carried out monthly throughout the year by specialized measuring systems, which include spectrum analyzers and antennas. Existing antennas have the following disadvantages: instability of the amplification gain, significant noise radiation, low reliability of pushbutton switches and significant weight. To eliminate these shortcomings, the design of an active antenna with a conical horn, which has the ability to change the parameters of the antenna within the entire range of 5 GHz. The optimal parameters of the horn are calculated as well. To obtain high values of the amplification gain of the horn antenna and maintain them with high stability at temperatures from -20 to +45оС used a signal amplification unit on a high-frequency operational amplifier SZA5044Z with a thermostat on a powerful transistor. Additional stability of the electrical characteristics of the amplifier is provided by double stabilization of the supply voltage. Electronic antenna control increases the reliability of the antenna by using electronic switching instead of push-button. Electronic control also protects the antenna amplifier from overheating, changing the polarity of the battery and electromagnetic interference. Laboratory and field studies of the directional horn antenna showed high stability of its parameters, reliability and ergonomics. Additional stability of the electrical characteristics of the amplifier is provided by double stabilization of the supply voltage. Electronic antenna control increases the reliability of the antenna by using electronic switching instead of push-button one. Electronic control also protects the antenna amplifier from overheating, change of the battery polarity and electromagnetic interference. Laboratory and field studies of the beam horn antenna showed high stability of its parameters, reliability and ergonomics.

Complete Target Coverage in Radio Frequency and Solar-Powered Sensor Networks

Future Internet of Things networks are likely to have radio frequency (RF) energy harvesting sensor devices and also solar-powered hybrid access points (HAPs) that help monitor one or more targets such as assets in a warehouse. In this setting, we outline three contributions that ensure devices' monitor targets at all times and upload the maximum number of samples to an HAP in order to ensure high monitoring quality. First, we outline a mixed integer linear program (MILP) and use it to optimize the transmission power of HAPs and time used by devices to harvest RF energy, monitor target(s), and data transmissions. Second, we propose two heuristic algorithms to solve large problem instances. The results show that our heuristics achieve almost 97% of the optimal result computed by the MILP.

Dielectric Permeability of Forestry Depending on Environmental Parameters in Radio Frequency Monitoring

Dielectric Permeability of Forestry Depending on Environmental Parameters in Radio Frequency Monitoring

Innovative Cloud-based Snooping Detection model in both Public and Private Infrastructure

Network access technologies, including Wi-Fi and 4G LTE, are becoming more and more popular in Cloud computing infrastructure due to their increased performance, reliabilities, and ease of development. Cloud consumers can collect and process real time and continuous sets of massive assets. The large data size and security concerns have resulted in an ever-increasing need for efficient paradigm concept to integrate the functionalities of data monitor, analysis and anomalous traffic behavior detection. The procedure of intercepting traffics assigned by Cloud consumers and passing through Cloud scheduler to the Cloud infrastructure data centers has been known as wireless packet sniffer. This could capture the entire packets and analyze the contents in both Private Cloud Network (PrCN) and Public Cloud Network (PuCN) in the RFMON (Radio Frequency MONitor) mode. After buffering the entire Cloud consumer’s images in the Cloud scheduler, further interpretation of the packets can be carried out to distinguish malicious from beneficial packets. We designed and developed an intrusion detection model, namely Cloud Snooping Disclosure (CSD) to monitor the Cloud consumer’s image traffic loads, detect the anomalous traffic behaviors, and block the malicious intrusion. Our heuristic is based on two major steps, Forward and Backward scanning process. The step includes the initialization process and installing the security parameters for both sides, Cloud users and Cloud scheduler, while the second one relates to capturing anomalous inter-VM traffics. Furthermore, our algorithm incorporates pcap library into Cloud scheduler so that any incongruous traffic behaviors can be reported and saved. Our system was inspired by some existing researches that applied sniffer software such as Ethereal, Tcpdump, and Snort. The simulation results indicate that the effectiveness of our heuristic had the ability to detect and eliminate approximately 107 anomalous traffic behaviors from five case trials that have been generated by CloudSim framework.

Digital compensation of lowpass filters imperfection in the Modulated Wideband Converter compressed sensing scheme for radio frequency monitoring

This paper focuses on non-ideal filters in a Modulated Wideband Converter (MWC) scheme. The MWC is a system that can sample a sparse wideband signal at sub-Nyquist rate. Generally, the output of the ideal MWC components will ensure a perfect reconstruction. In practice, the reconstruction should be based on the output of non-ideal components, especially filters. The impact of non-ideal filters will trigger to a bad reconstruction. In this paper, a detailed study on non-ideal lowpass filters imperfection used in compressed sensing MWC scheme is synthesized. A digital post-treatment scheme with amplitude and phase compensation is proposed after real lowpass filtering step in order to have the filtered output as close as the ideal lowpass filter output. At last, reconstruction spectra obtained from different simulated lowpass filters are compared with different parameters of MWC.

Optically controlled on-coil amplifier with RF monitoring feedback.

To develop a new optically controlled on-coil amplifier that facilitates safe use of multi-channel radiofrequency (RF) transmission in MRI by real-time monitoring of signal phase and amplitude. Monitoring was carried out with a 4-channel prototype system by sensing, down sampling, digitizing, and optically transmitting the RF transmit signal to a remote PC to control the amplifiers. Performance was evaluated with benchtop and 7 T MRI experiments. Monitored amplitude and phase were stable across repetitions and had standard deviations of 0.061 μT and 0.0073 rad, respectively. The feedback system allowed inter-channel phase and B1 amplitude to be adjusted within two iterations. MRI experiments demonstrated the feasibility of this approach to perform safe and accurate multi-channel RF transmission and monitoring at high field. We demonstrated a 4-channel transceiver system based on optically controlled on-coil amplifiers with RF signal monitoring and feedback control. The approach allows the safe and precise control of RF transmission fields, required to achieve uniform excitation at high field. Magn Reson Med 79:2833-2841, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Dependence of Dielectric Permittivity of Forest Fund by Climatic Factors in Radio Frequency Monitoring

Dependence of Dielectric Permittivity of Forest Fund by Climatic Factors in Radio Frequency Monitoring

Contactless Radio Frequency Monitoring of Dielectric Properties of Egg White During Gelation

The evaluation of dielectric properties in the radio frequency (RF) bandwidth is highly relevant to characterize the physical or physiological state of organic materials. This paper reports on the implementation of an easy-to-use and contactless RF dielectric sensing technique used for the monitoring of the heat-induced gelation of a white egg sample. The sensing technique basically consists in the distant monitoring of a high-quality factor inductive RF resonator operating at 98 MHz, which is electromagnetically coupled to the egg white sample. A lumped element modeling of the contactless RF probe interacting with the egg white is proposed. It is used to estimate both the conductivity and the permittivity of the sample during its gelation, starting from the impedance changes measured at the ends of the RF probe, and after probe calibration carried out using a reference NaCl solution. The results obtained during a 10 h monitoring experience allow the dynamics of the egg white gelation to be analyzed. These results open the way to the development of easy-to-implement and non-invasive dielectric monitoring of organic materials, with many prospects in agrifood as well as health monitoring applications.

МОДЕЛЬ ИНФОРМАЦИОННОГО ОБЕСПЕЧЕНИЯ СИСТЕМЫ ЛЕСОУПРАВЛЕНИЯ НА БАЗЕ РАДИОЧАСТОТНОГО МОНИТОРИНГА ЛЕСНОГО ФОНДА

МОДЕЛЬ ИНФОРМАЦИОННОГО ОБЕСПЕЧЕНИЯ СИСТЕМЫ ЛЕСОУПРАВЛЕНИЯ НА БАЗЕ РАДИОЧАСТОТНОГО МОНИТОРИНГА ЛЕСНОГО ФОНДА

Insulation State On-line Monitoring and Running Management of Large Generator

This study presented an insulation state monitoring method for large generator based on radio frequency (RF) technique. As an on-line condition monitor and the precondition of condition-based maintenance (CBM), the RF monitor used the high frequency current mutual inductor to detect the partial discharge signal from neutral wire of stator windings. According to the magnitude of indicative value of RF monitor, a five phase model was also proposed to manage the generator’s running better. The practices show that the proposed method is effective.

Characterization and mitigation of stray radiofrequency currents during monopolar resectoscopic electrosurgery

Study objective To determine patterns and range of stray radiofrequency (RF) currents flowing through the working element of monopolar resectoscopes during routine endometrial rollerball ablation or resection; and to determine whether straightforward modifications of the uterine resectoscope and the application of RF monitoring could provide a safe pathway for such currents. Design Prospective in vivo measurements (Canadian Task Force classification II-1). Setting University-affiliated teaching hospital. Patients Twelve women undergoing resectoscopic surgery. Interventions During routine resectoscopic surgery using 1.5% glycine irrigant solution, three modified 26F Storz resectoscope working elements (model 27070E) were adapted to be continuously monitored with an Encision AEM device for excessive capacitive coupling and other stray currents from insulation failure. Active electrodes used were 3 mm and 5 mm rollberballs and 8 mm–diameter cutting loops powered by ERBE or Valleylab generators at 120 W. Active and working element currents were monitored by Pearson current transformers followed by root-mean-squared detectors based on the Analog Devices AD-637 integrated circuit. Data were recorded using a Fluke 199C oscilloscope, then serially transferred to a notebook computer and analyzed using Flukeview, Excel, and Minitab software. Results Typical values of working element currents ranged from 0.10 to 0.20 A. Active electrode currents were typically in the range of 0.50 to 1.10 A. Frequently, the working element current exceeded the typical values and ranged up to 0.60 A. These current surges produced a heat factor (I 2t) of 0.45 A 2.sec in a 10-second period. Conclusions During resectoscopic electrosurgery, baseline, most likely capacitive coupled, currents were always present. In addition, high values of working element currents occurred frequently, and they surged up to 0.60 A for significant periods of time. Without the modification of the resectoscopic device, these currents have the capability of flowing through the patient’s genital tract and causing burns. Since monopolar electrosurgery remains an integral part of most hysteroscopic procedures, active electrode monitoring may offer a solution in protecting the patient and the surgeon from stray electrosurgical burns.

Intracardiac echocardiography-guided, anatomically based radiofrequency ablation of focal atrial fibrillation originating from pulmonary veins

ObjectivesIn patients with a pulmonary vein (PV) source for atrial fibrillation (AF), we sought the use of intracardiac echocardiography (ICE) to evaluate PV anatomy, guide radiofrequency (RF) ablation and monitor for acute stenosis during ablation. BackgroundA focal source for AF may be found in the proximal component of the PVs and can be effectively treated by ablative techniques. However, the procedure may be challenging due to the complex anatomy of the left atrium and PVs, uncertain catheter positioning within the PVs and difficulties in mapping atrial extrasystoles, which may be rare or repeatedly induce AF and require cardioversion. MethodsSixty-four patients were referred for RF ablation of a focal source of AF, and 56 were identified as having AF triggers in ≥1 PV. Using ICE guidance, RF lesions were applied around the circumference of the vein near the os until there was electrical isolation. ResultsLesions were placed in 82 veins (36 right superior PV, 33 left superior PV, 9 left inferior PV, 4 right inferior PV); 24 ± 12 lesions per vein were necessary to create electrical isolation with a fluoroscopic time of 11 ± 4 min and a mean of 22% reduction in luminal area. After a follow-up of 13 ± 7 months, 66% of patients remained free of AF, and another 13% responded better to medications. ConclusionsWe describe an anatomic approach to PV electrical isolation in which ICE is used to define the anatomy, guide RF ablation and monitor for acute PV changes.

A comparison of principal component analysis, multiway principal component analysis, trilinear decomposition and parallel factor analysis for fault detection in a semiconductor etch process

Multivariate statistical process control (MSPC) tools have been developed for monitoring a Lam 9600 TCP metal etcher at Texas Instruments. These tools are used to determine if the etch process is operating normally or if a system fault has occurred. Application of these methods is complicated because the etch process data exhibit a large amount of normal systematic variation. Variations due to faults of process concern can be relatively minor in comparison. The Lam 9600 used in this study is equipped with several sensor systems including engineering variables (e.g. pressure, gas flow rates and power), spatially resolved optical emission spectroscopy (OES) of the plasma and a radio-frequency monitoring (RFM) system to monitor the power and phase relationships of the plasma generator. A variety of analysis methods and data preprocessing techniques have been tested for their sensitivity to specific system faults. These methods have been applied to data from each of the sensor systems separately and in combination. The performance of the methods on a set of benchmark fault detection problems is presented and the strengths and weaknesses of the methods are discussed, along with the relative advantages of each of the sensor systems. Copyright © 1999 John Wiley & Sons, Ltd.

Development and Benchmarking of Multivariate Statistical Process Control Tools for a Semiconductor ETCH Process: Impact of Measurement Selection and Data Treatment on Sensitivity

Multivariate Statistical Process Control (MSPC) tools have been developed for monitoring a Lam 9600 TCP Metal Etcher at Texas Instruments. These tools are used to determine if the etch process is operating normally or if a system fault has occurred. Application of these methods is complicated because the etch process data exhibits a large amount of normal systematic variation. Variations due to faults of process concern can be relatively minor in comparison. The Lam 9600 used in this study is equipped with several sensor systems including engineering variables (e.g. pressure, gas flow rates and power), spatially resolved Optical Emission Spectroscopy (OES) of the plasma and a Radio Frequency Monitoring (RFM) system to monitor the power and phase relationships of the plasma generator. A variety of analysis methods and data preprocessing techniques have been tested for their sensitivity to specific system faults. These methods have been applied to data from each of the sensor systems separately and in combination. The performance of the methods on a set of benchmark fault detection problems will be presented and the strengths and weaknesses of the methods will be discussed, along with the relative advantages of each of the sensor systems.

Radio Frequency Response of a Large Turbine-Generator Stator Winding

Long term experience with on-line radio frequency monitoring of large turbine generators has shown a need for increased understanding of the propagation of arc generated radio frequency signals in a stator winding. This paper presents the results of an on going research program designed to obtain an increased understanding of radio frequency arc detection in large turbine generators. Test results from AC arcing response and sinewave response measurements made on a generator stator are presented in addition to the results obtained from a computer circuit analysis performed on a radio frequency circuit model of a portion of the same generator stator. These results led to a better understanding of RF arc signal propagation and helped to identify improved detection techniques. Three RF measurement techniques were studied for both the measurements and calculations, resulting in good agreement. Arc voltage detection sensitivity calculations give a minimum detectable level of arc voltage for each RF measurement technique.