Signal Field Strength Research Articles

SPATIAL PREDICTION OF RECEIVED SIGNAL STRENGTH FOR CELLULAR COMMUNICATION USING SUPPORT VECTOR MACHINE AND K-NEAREST NEIGHBOURS REGRESSION

Abstract. Signal strength maps are of great importance for cellular system providers in network planning and operation. Accurate prediction of signal strength is important for solving problems such as link quality. In this study, Received Signal Strength (RSS) prediction model is proposed for the 900 MHz band in the Van Yüzüncü Yıl University campus environment by using machine learning regression methods such as K- Nearest Neıghbours (KNN) and Support Vector Regression (SVR) together with Geographic Information Systems. For the training of this model, signal strength values taken from the RF Spectrum Analyser at different locations and distances were used. In addition, spatial data sets such as the digital elevation model, location of base stations and measurement stations, building heights and location, and land use/cover were used in the model. The effect of these data sets on RSS power is included in the model. The model aims to predict RSS accurately, visualize the estimated signal strength, and analyze the signal field strength coverage. Different kernels from the SVR model such as Polynomial, , and Sigmoid were tested. To increase the success of the model, appropriate parameter values were selected and configured according to SVR and KNN methods. For 900 MHz, the performances of SVR and KNN models were compared and the results of the models were verified using root mean squares (RMSE). Among the measured data, the lowest prediction is found in KNN Manhattan. According to the results of the simulation was observed that the SVR model created with spatial data performs better for Signal Strength. Finally, the lowest RMSE value (1.71 dB) was obtained from the Sigmoid kernel in the best signal strength estimation SVR model. The SVR model is recommended for Campus Area signal strength estimation.

Measurement and Calibration of EMF: A Study Using Phone and GBDT for Mobile Communication Signals

AbstractElectromagnetic exposure caused by mobile communication signals has always been a cause of concern. Due to the cost and inconvenience of professional measurement equipment, researchers have turned to smartphone APPs to study and assess the electric field strength caused by mobile communication signals. However, existing cell phone‐based measurements have two weaknesses. First, no system architecture suitable for large‐scale crowdsourced testing has been proposed. Second, since smartphone sensors cannot measure electric field strength directly, existing methods for converting the received signal power of the phone and electric field strength have errors of more than 5 dB. This paper proposes a measurement and calibration method for electric field strength of mobile communication signals based on a smartphone app and gradient boosting decision tree (GBDT). This method consists of a downlink signal acquisition system based on an APP and a calibration model based on GBDT to convert received signal power into electric field strength. The experimental results show that the proposed model achieves a R2 score of 0.93 and a MAE of 0.97 dB. Compared with the existing methods, our method improves the calibration accuracy by 4 dB, enabling large‐scale, low‐cost, and high‐precision direct measurement of the electric field strength of mobile communication signals.

Observations and analysis of the impact of annular eclipse on 10 MHz short-wave signal in Sanya area on June 21, 2020

This paper takes the annular solar eclipse that occurred in China on June 21, 2020, as the background and conducts tests and analysis of shortwave timing sky wave signals. The test group continuously tested the signal field strength data from June 20, 2020, to June 23, 2020. The results show that the shortwave signal field strength on June 21, the day of the annular eclipse, is significantly weaker than that on two other days—before and during the annular eclipse—and there are three obvious jumps in the field strength value. (1) The first jump occurs more than one hour before the annular eclipse, and then, the field strength has an oscillatory attenuation. Between the first jump and the second jump, the overall change trend of the field strength value is an oscillatory decline one. (2) About 25 min before the beginning of the eclipse, the second jump of the field strength occurs; from the second jump to the third jump, that is, before the occurrence of the beginning of the eclipse and the transition phase from the beginning to the middle of the eclipse, the value of the field strength has an oscillatory increase. (3) During the period of 8:00–8:10, the field strength shows a third jump. Although the field strength oscillates after the third jump, it has no obvious increasing or decreasing trend. Based on the results of previous studies on the annular eclipse on that day and the analysis of the theoretical model of radio wave propagation, this paper preliminarily considers that the change in signal field strength is supposed to be caused by the impact of the outbreak of the annular eclipse on the ionosphere. When the annular eclipse occurred, the sunlight reaching the ground is blocked by the Moon, and the ionization degree of electrons in the ionosphere is reduced, resulting in an increase in the penetration factor, and the overall performance of the shortwave signal reaching the ground is weakened.

Impact of the annular solar eclipse on June 21, 2020 on BPL time service performance

BPL is a special Chinese long-wave time service system constructed and maintained by the National Time Service Center of the Chinese Academy of Sciences. Two experimental paths were designed to analyze the impact of the annular solar eclipse that occurred on June 21, 2020, on the BPL time service performance. In the first path, the receiving point was located in the ring eclipse zone, whereas in the other path, the sky-wave reflection point was located in the ring eclipse zone. The time of arrival (TOA) data during 19–23 June 2020 at the Sanya test point (sky-wave reflection point located in the ring eclipse zone) and field strength from 21 to 22 June 2020 at the Xiamen test point (receiving point located in the ring eclipse zone) were measured and analyzed. The experimental results show that under normal conditions of BPL time service signal transmission, the TOA and field strength undergo significant changes during the annular solar eclipse, the TOA data change up to 5.17 µs, and the field strength data change up to 17.72 dBμV. The data tend to increase initially and then decrease. This change is consistent with the ionospheric change caused by the annular solar eclipse. The BPL time service performance is affected at the receiving points located in the south of the BPL time service station with the great circle distance ranging from 1426 to 1844 km.

Variation of Low-Frequency Time-Code Signal Field Strength during the Annular Solar Eclipse on 21 June 2020: Observation and Analysis.

Due to the occlusion of the moon, an annular solar eclipse will have an effect on the ionosphere above the earth. The change of the ionosphere, for the low-frequency time-code signal that relies on it as a reflection medium for long-distance propagation, the signal field strength, and other parameters will also produce corresponding changes, which will affect the normal operation of the low-frequency time-code time service system. This paper selects the solar eclipse that occurred in China on 21 June 2020, and uses the existing measurement equipment to carry out experimental research on the low-frequency time-code signal. We measured and analyzed the signal field strength from 20 June 2020 to 23 June 2020, and combined solar activity data, ionospheric data, and geomagnetic data, and attempted to explore the reasons and rules of the change of signal parameters. The results showed that the field strength of the low-frequency time-code signal changed dramatically within a short time period, the max growth value can reach up to 17 dBμV/m and the variation trend yielded ‘three mutations’. This change in signal field strength is probably due to the occurrence of a solar eclipse that has an effect on the ionosphere. When the signal propagation conditions change, the signal strength will also change accordingly.

Path Profile and Coverage Statistics of Selected Radio Stations for Microwave Propagation Design over a Tropical Location

Pathloss prediction is important for planning terrestrial radio communication at microwave frequencies. This necessitates the continuous evaluation of signal field strength dependence on path and channelcharacteristics. In this study, drive test analysis of received signal strength (RSS) from selected frequency modulated (FM) radio signals across different routes withinOndo State, Nigeria, was carried out. Signal strength distribution and coverage area statistics were evaluated for each channel on each route. The signals were measured from both high and low power transmitters using DBC BC 1173 digital signal level meter. Also, terrain elevations and location coordinates were measured using Garmin GPS 72 Personal Navigator. Location-specific pathloss model was developed for each transmitting station and their performance was evaluated against existing models. Dependence of signal strength on distance from the transmitter and path elevation was established following a least R2 value of 0.67 being returned from the comparative analysis between developed and existing models. This also indicates thatthe developed model is suitable for pathloss prediction within the location.

Method of measuring the mechanical properties of ferromagnetic materials based on magnetostrictive EMAT characteristic parameters

The mechanical and micromagnetc properties of ferromagnetic materials are overall associated with their microstructure parameters. The magnetostriction refers to one of the micromagnetic properties. The magnetostrictive properties of ferromagnetic materials are characterized by the relationships between the intensity of the SH (Shear Horizontal) waves with magnetostrictive effect under the identical excitation and the static bias magnetic induction intensity. In this study, the characteristic parameters exhibiting sensitivity to the magnetostrictive properties of ferromagnetic materials in the relationships between the intensity of EMAT (electromagnetic acoustic transducer) signal and static magnetic field strength were extracted. Besides, with BP (back propagation) neural network, the mapping association between the magnetostrictive parameters and the mechanical properties of the materials was developed, and the mechanical properties of the materials were non-destructively determined. By verifying the testing samples of cold-rolled steel specimens synthesized by Bao-steel Inc., the method was found to be capable of achieving high prediction accuracy; the passing rate of relative error less than 10% can reach 90%.

High-resolution signal-in-space measurements of VHF omnidirectional ranges using UAS

Abstract. In this paper, we describe measurement results of the signal-in-space of very high frequency (VHF) omnidirectional range (VOR) facilities. In aviation VOR are used to display the current course of the aircraft in the cockpit. To understand the influence of wind turbines (WT) on the signal integrity of terrestrial navigation and radar signals, the signal content and its changes, respectively, must be investigated. So far, only numerical simulations have been carried out on the frequency-modulation (FM) part of the Doppler-VOR (DVOR) signal to estimate the influence of WT on DVOR. Up to now, the amplitude-modulated (AM) part of the DVOR was not assessed at all. In 2016, we presented an unmanned aerial system (UAS) as a carrier for state-of-the-art radio-frequency (RF) measurement instrumentation (Schrader et al., 2016a, c; Bredemeyer et al., 2016), to measure and to record the true signal-in-space (both FM and AM signal) during the flight. The signal-in-space (which refers to time-resolved signal content and field strength, respectively) is measured and sampled without loss of information and, furthermore, synchronously stored with time stamp and with precise position in space, where the measurements were taken.

A method for evaluating microwaves entanglement efficiency based on second-order correlation detection

A method for evaluating the entanglement efficiency of dual-path entangled microwaves based on second-order correlation detection is proposed in this paper. The relationship between the squeezing degree and the entanglement efficiency in the lossless case was analyzed using the second-order interference visibility as the indicator based on measurements of the signal field strength. A loss model was established to analyze the relationship between the average thermal photons, squeezing degree, and entanglement efficiency in the lossy case. The results show that in the lossless case, a larger squeezing degree leads to a lower percentage of entangled photons, giving a lower entanglement efficiency. The entanglement efficiency first increases and then decreases with the increase of the squeezing degree in the lossy case, where the maximum achievable entanglement efficiency depends on the average thermal photons. The lower number the average thermal photons, the higher the maximum achievable entanglement efficiency, and the lower the corresponding squeezing degree. The research results provide a theoretical reference to balance the entanglement degree and entanglement efficiency of industrially-prepared dual-path entangled microwaves.

Assessment and Modeling of GSM Signal Propagation in Uyo, Nigeria

High quality of service is a paramount concern in wireless networks. One of the strategies in achieving optimal performance is to use wireless empirical models to predict wireless link quality factors such as path loss and the received power in any given transmission domain with irregular terrain. The primary goal of this study is to develop a radio wave propagation model for Uyo metropolis. An assessment was carried out in three major roads within the city of Uyo in Akwa Ibom State, to determine the quality of GSM signal reception by measuring the signal field strength, magnetic field strength, and power density of the base transceiver stations. The measurements were carried out using radio frequency electromagnetic field strength meter over a distance of 2000 meters from the base stations. The results of the measurements were analysed and a path loss model was developed for Uyo using linear regression model. Three empirical models: Okumura-Hata model, COST-Hata model, and Egli model were also applied in predicting the path loss in Uyo and the results obtained were compared with the developed model for Uyo metropolis. The comparison showed that Route D model had a better comparison factor with the developed model while the Okumura-Hata and COST-Hata were almost the same with more loss as the distance increased. In all the measurements, the standard deviation was between 3.31 dB and 3.36 dB.

Assessment and Modeling of GSM Signal Propagation in Uyo, Nigeria

High quality of service is a paramount concern in wireless networks. One of the strategies in achieving optimal performance is to use wireless empirical models to predict wireless link quality factors such as path loss and the received power in any given transmission domain with irregular terrain. The primary goal of this study is to develop a radio wave propagation model for Uyo metropolis. An assessment was carried out in three major roads within the city of Uyo in Akwa Ibom State, to determine the quality of GSM signal reception by measuring the signal field strength, magnetic field strength, and power density of the base transceiver stations. The measurements were carried out using radio frequency electromagnetic field strength meter over a distance of 2000 meters from the base stations. The results of the measurements were analysed and a path loss model was developed for Uyo using linear regression model. Three empirical models: Okumura-Hata model, COST-Hata model, and Egli model were also applied in predicting the path loss in Uyo and the results obtained were compared with the developed model for Uyo metropolis. The comparison showed that Route D model had a better comparison factor with the developed model while the Okumura-Hata and COST-Hata were almost the same with more loss as the distance increased. In all the measurements, the standard deviation was between 3.31 dB and 3.36 dB.

Slowing the probe field in the second window of double-double electromagnetically induced transparency

For Doppler-broadened media operating under double-double electromagnetically induced transparency (EIT) conditions, we devise a scheme to control and reduce the probe-field group velocity at the center of the second transparency window. We derive numerical and approximate analytical solutions for the width of EIT windows and for the group velocities of the probe field at the two distinct transparency windows, and we show that the group velocities of the probe field can be lowered by judiciously choosing the physical parameters of the system. Our modeling enables us to identify three signal-field strength regimes (with a signal-field strength always higher than the probe-field strength), quantified by the Rabi frequency, for slowing the probe field. These three regimes correspond to a weak signal field, with the probe-field group velocity and transparency window width both smaller for the second window compared to the first window, a medium-strength signal field, with a probe-field group velocity smaller in the second window than in the first window but with larger transparency-window width for the second window, and the strong signal field, with both group velocity and transparency window width larger for the second window. Our scheme exploits the fact that the second transparency window is sensitive to a temperature-controlled signal-field nonlinearity, whereas the first transparency window is insensitive to this nonlinearity.

Discussion on Active Television Interference Characteristic of UHV AC Transmission Line

High-voltage transmission line corona and sparking will bring television interference (TVI). Study has been seldom executed about active TVI from HV transmission line, and much less research on UHV AC lines. Based on present literatures, this paper brings forward test method of TVI from HV transmission line. Near straight span and tension tower of Chinese UHV AC Pilot Demonstration Project, several tests about TV picture, TVI field strength, the television signal field strength before and after lines energized, has been carried out in good weather. According to observation, interference characteristics to TV picture has been analyzed. Results indicate that, with increasing distance from the outer phase, UHV single circuit TVI field strength in fine weather attenuates negative exponentially. This paper illustrates it is questionable to use CISPR quasi-peak value for assessment of interference on TV picture caused by UHV transmission line corona and sparking noise.

PER Estimation of AIS in Inland Rivers based on Three Dimensional Ray Tracking

The Automatic Identification System (AIS) is an important maritime safety device, which is populous in inland rivers. Compared with that in open sea, the Package Error Rate (PER) of AIS in inland river has increased sharply due to its complex environment. With the help of hardware in loop simulation, it is possible to make statistical calculation on the PER under a given field strength and describe the data by quadratic rational fraction. Meanwhile, in the three dimensional software environments, the signal field strength is able to be calculated by the ray tracking method, which exhausts all the possible propagation paths, including direct way, reflection, diffractions, and the other medium attenuation matters. Beyond that, in the model, the propagation geography information in inland rivers is required to be simplified in some way, or the computation of the ray tracking is too hard to get. The paper set the Changjiang Wuhan channel as the field testing region, and all the deviations are less than 5% in sunny weather, which proves the method accurate and effective.

Perspectives and Limitations of Current Theories in Neuroscience and Cosmology in Describing “Full, Conscious and Actual Participation in Liturgical Celebrations”

Mother Church earnestly desires that all the faithful should be led to that fully conscious, and active participation in liturgical celebrations which is demanded by the very nature of the liturgy....

Time-domain modeling for shielding effectiveness of materials against electromagnetic pulse based on system identification

Shielding effectiveness (SE) of materials against electromagnetic pulse (EMP) cannot be well estimated by traditional test method of SE of materials which only consider the amplitude-frequency characteristic of materials, but ignore the phase-frequency ones. In order to solve this problem, the model of SE of materials against EMP was established based on system identification (SI) method with time-domain linear cosine frequency sweep signal. The feasibility of the method in this paper was examined depending on infinite planar material and the simulation research of coaxial test method and windowed semi-anechoic box of materials. The results show that the amplitude-frequency and phase-frequency information of each frequency can be fully extracted with this method. SE of materials against strong EMP can be evaluated with time-domain low field strength (voltage) of cosine frequency sweep signal. And SE of materials against a variety EMP will be predicted by the model.

CHARACTERISTICS OF ACTIVE AERIALS OF ONBOARD AVIATION NAVIGATION-LANDING EQUIPMENT

Active aerials (AA) or aerials-strengtheners are devices, that unite aerial and active elements of strengthening, transformation or generation of signals. Integration of aerials and active elements allows to decrease the sizes of aerials, to extend the band pass of aerials, to improve the sensitiveness of receiving aerials, carry out the electronic tuning of aerials, to increase effective antenna balance with transmission line, to improve electromagnetic compatibility of the radiosystems. Electromagnetic compatibility (ЕМС) of АА is determined by next characteristics: a dynamic range, blocking, intermodulation, cross modulation. Quantitative characteristics of EMC AA onboard aviation navigation-landing equipment of IV generation determined as to field strengths of noises and signals that is set by the requirements of ARINC and NLGS 3. Are represented the researches technique of characteristics of active aerials navigation landing apparatus in ground or in laboratory terms by means of standard measuring apparatus. The results of measuring showed that technical requirements to characteristic of ЕМС active aerial AP-001M of course receiving apparatus were executed in part: of dynamic range, blocking, mutual and cross modulation, and also intermodulation.

Investigation of the receivability of VLF standard time and frequency signals in Zaria, Nigeria

This study is on the receivability of some standard time and frequency signals in the VLF range in Zaria, Nigeria. Signal field strengths of various stations were estimated, and a suitable radio receiving system was set up to receive them. Using the assembled receiver, some of the transmissions, including the Omega W/L at Monrovia, Liberia, and GBR at Rugby, United Kingdom, were received and identified. Keywords: signal, receiver, standard time, standard frequency Nigerian Journal of Physics Vol. 17, 2005: 72-77

Comparison of physiological noise at 1.5 T, 3 T and 7 T and optimization of fMRI acquisition parameters

Previous studies have shown that under some conditions, noise fluctuations in an fMRI time-course are dominated by physiological modulations of the image intensity with secondary contributions from thermal image noise and that these two sources scale differently with signal intensity, susceptibility weighting (TE) and field strength. The SNR of the fMRI time-course was found to be near its asymptotic limit for moderate spatial resolution measurements at 3 T with only marginal gains expected from acquisition at higher field strengths. In this study, we investigate the amplitude of image intensity fluctuations in the fMRI time-course at magnetic field strengths of 1.5 T, 3 T, and 7 T as a function of image resolution, flip angle and TE. The time-course SNR was a similar function of the image SNR regardless of whether the image SNR was modulated by flip angle, image resolution, or field strength. For spatial resolutions typical of those currently used in fMRI (e.g., 3 × 3 × 3 mm 3), increases in image SNR obtained from 7 T acquisition produced only modest increases in time-course SNR. At this spatial resolution, the ratio of physiological noise to thermal image noise was 0.61, 0.89, and 2.23 for 1.5 T, 3 T, and 7 T. At a resolution of 1 × 1 × 3 mm 3, however, the physiological to thermal noise ratio was 0.34, 0.57, and 0.91 for 1.5 T, 3 T and 7 T for TE near T2*. Thus, by reducing the signal strength using higher image resolution, the ratio of physiologic to image noise could be reduced to a regime where increased sensitivity afforded by higher field strength still translated to improved SNR in the fMRI time-series.

Statistics of polarization and Stokes parameters of stochastic waves

Several theories now exist to describe the probability distribution functions (PDFs) for the electric field strength, intensity, and power of signals. In this work, a model is developed for the PDFs of the polarization properties of the superposition of multiple transverse wave populations. The polarization of each transverse wave population is described by a polarization ellipse with fixed axial ratio and polarization angle, and PDFs for the field strength and phase. Wave populations are vectorially added, and expressions found for the Stokes parameters I , U , Q , and V , as well as the degrees of linear and circular polarization, and integral expressions for their statistics. In this work, lognormal distributions are chosen for the electric field, corresponding to stochastic growth, and polarization PDFs are numerically calculated for the superposition of orthonormal mode populations, which might represent the natural modes emitted by a source. Examples are provided of the superposition of linear, circular, and elliptically polarized wave populations in cases where the component field strength PDFs are the same, and where one field strength PDF is dominant.