Narrowband Interference Research Articles

Narrow-band optical filter for a spectral-selective control device of physical and physicochemical processes

Subject of the present paper is the application of a multichannel optical spectrometer performing spectral measurements in specified areas of the optical range using a set of narrow-band interference optical filters that are tuned to certain wavelengths. Tasks of monitoring and controlling the physical and physico-chemical processes and the prospects of using non-contact optical spectroscopy for their solution are considered. Recommendations are given both on the choice of materials for infrared and visible filters. A visible range filter based on a combination of zirconium oxide and silicon oxide layers has been developed.

ANALYSIS OF UWB BASED ANTENNA FOR WIRELESS COMMUNICATION

Ultra-wideband wireless communications techniques have many merits, including an extremely simple radio that inherently leads to low-cost design, large processing gain for robust operations in the presence of narrowband interference, covert operations, and fine time resolution for accurate position sensing. However, there are a number of challenges in UWB receiver design, such as capturing multipath energy, inter symbol interference especially in a non-line-of-sight environment, and the need for high-sampling-rate analog-to-digital converters. Microstrip Patch antenna (MPA) provides low profile and low volume, so it is use in a now a days communication devices. In this paper study of past few year shows that most of labour on MPA is targeted on planning compact sized microstrip antenna. A novel ultra-wideband printed monopole antenna can be used in wireless communication devices.

FH-BOC: generalized low-ambiguity anti-interference spread spectrum modulation based on frequency-hopping binary offset carrier

ObjectiveThe paper aims to present a generalized modulation scheme that can improve the anti-interference performance of global navigation satellite systems (GNSS) and mitigate the ambiguity problem in BOC modulation.Summary background dataWith the exponential growth of location-based services, there is a need to improve the positioning accuracy and the capability to resist against external interference in challenging environments, such as urban canyons, forested terrains, and indoor areas, in which signal attenuation, interference, and multipath fading can seriously degrade the positioning accuracy of global navigation satellite systems (GNSS) and GNSS-like systems. The binary offset carrier (BOC) modulation has been adopted in GNSSs because of its good spectral isolation from heritage signals, high accuracy, multipath interference resistance, and flexibility in signal implementation compared with BPSK-R modulation. However, for high-order BOC modulation, the main drawback is the ambiguity in tracking due to the multiple side peaks of the autocorrelation function (ACF). The receiver may incorrectly lock onto one of these side peaks, causing intolerable measurement bias, and this undesirable behavior limits the application of this modulation scheme in navigation systems.MethodsWe present a generalized low-ambiguity anti-interference spread spectrum modulation based on frequency-hopping BOC (FH-BOC). First, we formulate the mathematical model of FH-BOC modulation and derive the analytical expressions for the normalized ACF and PSD, and we analyze the time and frequency properties of several representative FH-BOC signals. Next, we present recommended parameter selections, a generation and detection scheme for FH-BOC modulation. Finally, we analyze the characteristics of the ACF and PSD, the tracking performance, the spectral separation, and the anti-narrowband interference and multipath interference performance for several specific BOC and FH-BOC signals.ResultsThe results show that FH-BOC with the largest frequency-hopping band has lower ACF ambiguity, better anti-interception performance, and better anti-intrasystem interference, narrowband interference, and multipath interference performance than BOC modulation with the same main lobe bandwidth (MLB). The tracking and anti-interference performance of FH-BOC is similar to that of BOC modulation with the same ACF main peak width.ConclusionsFH-BOC is a generalized type of modulation that includes BOC modulation. The proposed FH-BOC signal improves the anti-interference performance and mitigates the ACF ambiguity problem of BOC modulation. The acquisition time and complexity of the receiving process for the proposed FH-BOC signal are the same for the BOC signal with the same MLB. The new modulation scheme which we proposed can serve as a new paradigm for the next-generation GNSS signal design, especially military signal design. It can also be used in the signal design for GNSS-like systems, such as systems for indoor positioning, GNSS enhancement, and pseudolite-based positioning.

Time-resolved optical characterization of the interaction between a laser produced plasma and a spark discharge

The interaction between a nanosecond laser produced plasma and a unipolar high voltage discharge was analyzed using time-resolved spectroscopy, fast photography with narrow band interference filters and profilometry. Here the laser ablation fluence was varied in the 60–1000 J/cm2 range. The 600-kW electrical discharge was triggered by an ablation plasma on the aluminum target at time 700 ns in order to enhance the laser-induced breakdown spectroscopy (LIBS) emission. Most of the spectra were obtained from a spot 1 mm above the target and these were: time-integrated to gauge overall enhancement and time-resolved to investigate emission enhancement, temperature and density as a function of time. It was found that the time-and-space integrated LIBS signal was enhanced by up to one order of magnitude at the lowest laser fluence employed when compared with a conventional LIBS experiment. Also, that this emission increment could not be mainly attributed to an increased mass removal, but rather to an enhancement of plasma ionization degree as was observed by means of fast photography with filters. This causes longer plasma duration and more enhancement of ionic species than neutrals. It was also found that both the electronic density and the temperature increase when the spark discharge is applied, in comparison with the ablation plasma. Emission enhancement is inversely proportional to laser fluence due to the fact that for higher fluences, by the time the discharge is applied, the laser-produced plasma is already highly excited.

Robust Estimation of Arrival Time of Complex Noisy Partial Discharge Pulse in Power Cables Based on Adaptive Variational Mode Decomposition

Periodic narrowband signals and white noise are the main interferences in online detection and localization of cable partial discharge (PD), however, existing research has always focused on the white noise suppression only, which is not in line with the actual scene. A novel de-noising method for effectively extracting random PD pulse from complex and strong interferences is proposed in this paper and applied to PD localization. Firstly, an improved adaptive variational mode decomposition (AVMD) is used to decompose periodic narrowband interference, white noise, and PD signal into different intrinsic mode. According to the characteristic that the power of intrinsic mode component of periodic narrowband interference in the discrete Fourier transformation (DFT) power spectrum is much larger than that of PD and white noise, the periodic narrowband is removed out. In order to effectively filter out white noise, a scale adaptive wavelet packet decomposition method based on correlation coefficient is proposed, which decomposes the signal into high, middle, and low-frequency components. The components with low frequency, small amplitude are removed out as the white noise interference according to the threshold method, and the residual is the de-noising PD signal. Experimental results show that the proposed method can robustly suppress the interference of periodic narrowband signal and white noise, and effectively preserve the essential characteristics of the real PD signal. In the multi-sensor travelling wave based localization system of cable PD source using time-varying kurtosis, accurate estimation of first arrival time of PD pulse can be achieved by the de-noising results.

Energy-minimizing bit allocation for powerline OFDM with multiple delay constraints

We propose a bit-allocation scheme for powerline orthogonal frequency-division multiplexing (OFDM) that minimizes total transmit energy subject to total-bit and delay constraints. Multiple delay requirements stem from different sets of data that a transmitter must time-multiplex and transmit to a receiver. The proposed bit allocation takes into account the channel power-to-noise density ratio of subchannels as well as statistic of narrowband interference and impulsive noise that is pervasive in powerline communication (PLC) channels. The proposed scheme is optimal with 1 or 2 sets of data, and is suboptimal with more than 2 sets of data. However, numerical examples show that the proposed scheme performs close to the optimum. Also, it is less computationally complex than the optimal scheme especially when minimizing total energy over large number of data sets. We also compare the proposed scheme with some existing schemes and find that our scheme requires less total transmit energy when the number of delay constraints is large.

Adaptive Narrow-Band Interference Suppression and Performance Evaluation Based on Code-Aided in GNSS Inter-Satellite Links

In this paper an adaptive narrow-band interference (NBI) suppression scheme based on a code-aided technique in the global navigation satellite system inter-satellite links (ISLs) is proposed. Unlike the commonly used infinte impulse response (IIR) notch filter and frequency domain filtering, the code-aided technique does not require interference detection or fast Fourier transforms, and the adaptive performance is better. We introduce the principle and implementation of code-aided technique, and the concept of interference influence coefficient is proposed to evaluate the influence of residual interference on the carrier-to-noise ratio (CNR) at the receiving end. Through simulation and by combining the tracking CNR after antijamming, the optimal antijamming parameters and scheme are obtained. Meanwhile, we analyze the relationship between the loss of CNR caused by residual interference and the interference influence coefficient. The final results of the bit error rate (BER) and ranging error in ISLs indicate that the adaptive interference suppression scheme based on the code-aided technique can effectively suppress NBI and ensure the reliability of ISL communications. In the case where the pseudo code rate is 10.23 MHz and the BER does not exceed $1 \times {10^{ - 5}}$ , for the NBI with a bandwidth of 2 MHz, the maximum interference-to-signal ratio (ISR) that can be suppressed by the proposed scheme is 40 dB. For the NBI with a bandwidth of 1 MHz, the maximum ISR that can be suppressed is 55 dB, and for single frequency interference, the maximum ISR that can be suppressed is 75 dB.

Multiple Interacting Narrowband Interferences Suppression Algorithm for OFDM Systems

The OFDM technology is widely used in wireless communication systems, but it is highly sensitive to narrowband interference (NBI). The existing NBI suppression algorithms are mainly for single NBI or multiple NBIs with an assumption that the frequency distance of the multiple NBIs is large enough. However, in reality, there are more and more multiple interacting NBIs with small frequency distance, such as NB-IoT. Unfortunately, due to the interaction of multiple NBIs, the performance of existing NBI suppression algorithms is degraded. Aiming at this problem, we propose a multiple interacting NBIs suppression algorithm jointed time-frequency domain for OFDM systems. First, in order to achieve a high-precision and low-complexity frequency estimate for a single NBI, an interference frequency estimation method based on chirp-z transform (CZT-IFE) is studied. Then, for multiple interacting NBIs, based on the analysis of NBI frequency distance and spectral aliasing, a highly robust interference frequency estimation method combining IIR notch filter and CZT-IFE (NF-CZT-IFE) is given. It eliminates the interaction of multiple NBIs and obtains the accurate frequency estimates of the NBIs. Finally, based on NF-CZT-IFE, the multiple interacting NBIs are suppressed by using IIR notch filters. Simulation results demonstrate that the proposed multiple interacting NBIs suppression algorithm has better interference suppression performance on the NBIs with different frequency distances and different interference numbers. The proposed algorithm improves the robustness of OFDM systems in complex NBI environments.

Performance of UWB communication systems in presence of perfect/imperfect power control MAI and IEEE802.11a interference

This paper evaluates the bit error rate performance of Impulse Radio-Ultra-Wideband (IR-UWB) communication system under the impact of both multiple access and narrowband interferences operating. The Narrowband Interference (NBI) signal is modelled as the IEEE802.11a orthogonal frequency division multiplexing-based wireless local area network signal, which can be approximated by the sum of independent asynchronous tone interferers with arbitrary frequencies. Multiple Access Interference (MAI) is assumed a zero mean Gaussian process, where it has been investigated in both perfect and imperfect power control scenarios. The bit error rate performance is evaluated in three different channel models: ideal channel model (additive white Gaussian noise channel), Nakagami-m multipath fading channel model and the IEEE802.15.3a UWB channel model. It will be shown that the performance of a UWB system is severely degraded due to the presence of both types of interference, yet the NBI has more impact on the performance of UWB communication systems compared to the multiple access one.

A narrowband interference suppression method based on adaptive WPT

A narrowband interference (NBI) suppression method based on adaptive WPT is proposed. Firstly, the optimum parameters of the frequency shift and the highest resolution level are selected using Genetic algorithm. Then the adaptive wavelet packet decomposition based on parity checking is done to the shifted signal. Finally the interference-free signal is obtained by setting the sub-band with interference to zero and being reconstructed. Simulation results show that this algorithm can both suppress single tone and multi-tone interference effectively.

Technique of radio suppression of a radio communication system in a Wі­Fі network from noise­like signals based on the HTTP/3 рrotocol

The article presents the results of the analysis of the existing method of radio suppression of radio communication systems in Wi-Fi networks, and conclusions are drawn regarding ways to increase its effectiveness. The method of radio suppression of radio communication systems with noise-like signals was chosen. It contains the implementation of structural obstacles and a scheme for smooth control of their power implemented in the HTTP/3 protocol. This makes it possible to increase the effectiveness of a jamming station with radio suppression of certain radio communication systems and reduce radioelectronic control equipment requirements. For the applied implementation of this technique in a jamming station, it is necessary to predict a reconnaissance tool covering the reception, determination and estimation of the parameters of noise-like signals; structural interference block; unit execution and regulation of the required power level of structural interference. One of the main tasks is to suppress radio communication systems (SRS). However, with the advance of digital technologies in speech and data transmission, noise-signaling (SHP) signals are increasingly being used to improve the noise immunity and latency of SRHs. One way to implement such signals is to modulate the carrier frequency by a pseudorandom sequence. The issue with productive radio suppression (RP) of SRWs with SHPS has been developing quite actively in recent years, and still remains relevant. Based on the features and means of electronic warfare (EWB), the SPS radio communications systems may be muted by the application of high-power shielding, narrowband or pulse interference. But this method does not cover minimization of radiolabeling of EW methods and can lead to electromagnetic compatibility violations.

Binary Sequence Set Design for Interferer Rejection in Multi-Branch Modulation

Wideband communication is often expected to deal with a very wide spectrum, which in many environments of interest includes strong interferers. Thus receivers for the wideband communication systems often need to mitigate interferers to reduce the distortion caused by the amplifier nonlinearity and noise. Recently, a new architecture for communication receivers known as random modulation mixes a signal with different pseudorandom sequences using multiple branches of channels before sampling. While random modulation is used in these receivers to acquire the signal at low sampling rates, the modulation sequences used lack the ability to suppress interferers due to their flat spectra. In previous work, we introduced the design of a single spectrally shaped binary sequence that mitigates interferers to replace the pseudorandom sequence in a channel. However, the designed sequences cannot provide the stable recovery achieved by pseudorandom sequence approaches. In this paper, we extend our previous sequence design to guarantee stable recovery by designing a set of sequences to be orthogonal to each other. We show that it is difficult to find the necessary number of sequences featuring mutual orthogonality and introduce oversampling to the sequence set design to improve the recovery performance. We propose an algorithm for multi-branch sequence design as a binary optimization problem, which is solved using a semidefinite program relaxation and randomized projection. While it is common to model narrowband interferers as a subspace spanned by a subset of elements from the Fourier basis, we show that the Slepian basis provides an alternative and more suitable compact representation for signals with components contained in narrow spectrum bands. Numerical experiments using the proposed sequence sets show their advantages against pseudorandom sequences and our previous work.

Performance of UWB communication systems in presence of perfect/imperfect power control MAI and IEEE802.11a interference

This paper evaluates the bit error rate performance of Impulse Radio-Ultra-Wideband (IR-UWB) communication system under the impact of both multiple access and narrowband interferences operating. Th...

Двухэтапный синтез структурированных микросистем из наностержней оксида цинка с использованием ультразвукового спрей-пиролиза и низкотемпературного гидротермального метода

The features of a two-stage synthesis of structured microsystems based on zinc oxide nanorods using ultrasonic spray pyrolysis and a low-temperature hydrothermal method with suppression of nucleation in the bulk of the solution are presented. It is shown that the use of two-stage synthesis provides control over the size and aspect ratio of nanorods. It is proposed to control the concentration of intrinsic surface defects by measuring the photocurrent with irradiation through narrow-band interference light filters.

STUDIES ON THE DETERMINATION OF THE TOTAL HARDNESS OF THE DRINKING WATER COMING FROM THE "FÂNTÂNILE RECI" SPRING IN MARAMUREŞ

The paper showcases research conducted in order to determine the total hardness of the drinking water coming from the "Fântânile Reci" spring, located at the edge of the DN18 road, at the end of the Mara town, in Maramures, Romania. A HI97735 advanced portable photometer was used for this experiment. The photometer can perform low, medium and high range measurements of the total hardness of the water samples. The counter comes equipped with a superior optical system which uses a reference detector and a narrowband interference filter used for extremely quick and repeatable measurements. The values obtained as the result of the experiment are: 204 mg/l CaCO 3 (Total Hardness MR), 15,2 °E, 12,2°dH and 21,7°f. The LED light sources are superior compared to the tungsten lamps. LED lights are more efficient, providing more light while using less energy, and they produce little heat, which could otherwise affect the electrical balance.

Comparison Study of Time Synchronization in NC-OFDM Systems Based on Symmetric Correlator

NC-OFDM as one of the candidates for the Cognitive Radio (CR) system has many challenges in the synchronizing time. This is due to the frequency sharing which can cause Narrowband Interference (NBI), which causes a very significant time synchronization error. Large errors in time synchronization can reduce overall NCOFDM system performance. In this study, we evaluate the time synchronization performance of NC-OFDM systems on the multipath channel in the present of NBI. We provide an evaluation of the time synchronization performance by comparing the time synchronization algorithm that has a timing metric such as an impulse-like (Symmetric correlator). Here, we present three algorithms that use the symbol training to calculate the arrival time of the NC-OFDM symbol. The simulation conducted by considering the effects of multipath channel, Signal to Noise Ratio (SNR), Carrier Frequency Offset (CFO), and SIR (Signal to Interference Ratio). SIR is modeled with NBI. Algorithm performance is measured by MAE (Mean Absolute Error) and MSE (Mean Squared Error). Simulation results show that the autocorrelation-based method has very poor performance in MAE and MSE tests, so it is not suitable for NC-OFDMbased Cognitive Radio systems. The GLRT (Generalized Likelihood Ratio Test) method and Iterative Normalization method perform well in case the NC-OFDM Cognitive Radio systems.

Reweighted Tensor Factorization Method for SAR Narrowband and Wideband Interference Mitigation Using Smoothing Multiview Tensor Model

For the interference suppression problem on synthetic aperture radar (SAR) systems, traditional methods have focused on how to remove one kind of interference through nonparametric methods and parametric methods. However, complicated interferences, including both narrowband interferences (NBIs) and wideband interferences (WBIs), severely affect SAR imaging in practical scenarios. Also, the spectra of the complicated interferences can be continuously distributed, which are even harder to mitigate from the received signal. Hence, in this article, we propose a smoothing multiview (SMV) tensor model in range-azimuth-space domain to represent the intrinsically unified characteristics of the NBIs and the WBIs for SAR systems, reserving more azimuth degrees-of-freedom (DOFs) than the previous MV tensor model. The proposed SMV tensor model can enhance the potential low-rank property of the complicated interferences, even though the interferences may be continuously distributed in low-dimensional domains. Moreover, due to the larger scale of the SMV model than those of the traditional models, a complex reweighted tensor factorization (CRTF) algorithm is proposed to factorize the large-scale tensor into the product of two small-scale tensors, achieving both better computational efficiency and better low-rank approximation of complicated interferences. Finally, the measured SAR data with different kinds of simulated complicated interferences are employed to demonstrate the effectiveness and efficiency of the newly designed SMV model and the proposed method compared with the MV model and the complex tensor robust principal component analysis (CT-RPCA) method.

Direct sequence spread spectrum communication narrowband interference cancelation in compressed domain

AbstractDue to the broad bandwidth nature of the direct sequence spread spectrum (DSSS) signal, the application of narrowband interference (NBI) cancelation algorithms based on the Nyquist‐Shannon sampling theory are limited by the high sampling rate. To solve the sampling and processing difficulty in the traditional DSSS communication interference cancelation method, we used the compressive sensing (CS) to reduce the sampling rate of the DSSS communication system, and further proposed a compressed domain NBI elimination method in this study. We proved that NBI with a certain bandwidth and DSSS signal are both sparse in specific dictionaries and proposed the corresponding sparse dictionary construction method. Detailed analysis of the compressed domain features of NBI and the DSSS signal demonstrated that it is possible to extract the strong NBI components from the compressed measurements. Two compressed domain NBI cancelation algorithms were proposed based on this idea. The extracted NBI components were filtered out from the compressed measurements directly in the first algorithm, and then we achieved the DSSS signal demodulation in compressed domain using the separated DSSS signal components with the orthogonal matching pursuit (OMP) algorithm. A proposed extraction filter block sparse Bayesian learning (EFBSBL) framework algorithm was utilized to estimate the NBI from the compressed measurements in the second algorithm. The estimated NBI was eliminated from the received signal, and then we recompressed the DSSS signal after NBI cancelation and realized the DSSS signal demodulation in compressed domain with the OMP algorithm. Simulation results support our theoretical analysis results and reveal that the two proposed algorithms are both effective for NBI cancelation and significant interference cancelation performance are achieved.

A Novel Tensor Technique for Simultaneous Narrowband and Wideband Interference Suppression on Single-Channel SAR System

Nowadays, in the electromagnetism environment, the complex interferences, including the narrowband interferences (NBIs) and wideband interferences (WBIs), may severely affect the imaging quality of synthetic aperture radar (SAR) systems. Most traditional methods can only tackle with one kind of isolated interferences, NBIs or WBIs, which are widely distributed in the 1-D range frequency domain or 2-D range time–frequency domain. In this paper, we propose a complex tensor robust principal component analysis (CT-RPCA) method based on a novel 3-D range-azimuth-space tensor model to mitigate continuously distributed NBIs and WBIs simultaneously. The main contributions of this paper are summarized in three aspects. First, we strictly prove the low-rank property of the isolated NBIs and WBIs in the range-azimuth domain. Second, we use multiple views of the signal to construct a novel 3-D range-azimuth-space tensor model, where both the NBI tensor and the WBI tensor have spatial low-rank property due to the approximately stable frequency bands along the spatial dimension. Third, the CT-RPCA method is employed to efficiently suppress NBIs and WBIs simultaneously by solving the tensor RPCA problem. Finally, the real SAR data with simulated complex interferences are employed to demonstrate the effectiveness of the proposed method.

Computationally Efficient Algorithm for Estimating the Frequency of Signals at the Output of a Channel with White Gaussian Noise and Narrowband Interference

Abstract—A computationally efficient algorithm is proposed for estimating the frequency of a quasi-harmonic signal in the presence of narrowband interference based on iterative calculation of the autocorrelation sequence. A feature of the algorithm is the use of an additional filtering procedure that improves its stability. Simulation results have confirmed the proximity of the estimates obtained to the theoretical boundaries.