Noise-like Signals Research Articles

ИСПОЛЬЗОВАНИЕ МОДУЛЯЦИИ LORA В СРЕДСТВАХ РАДИОСВЯЗИ, НАВИГАЦИИ И НАБЛЮДЕНИЯ ДЛЯ РЕШЕНИЯ ЗАДАЧ УПРАВЛЕНИЯ ВОЗДУШНЫМ ДВИЖЕНИЕМ

The paper considers the use of LoRa technology in the data transfer system for performing aircraft position-fixing by means of the network of multilateration ground stations. The urgency of the problem is that the methods used for transferring data do not meet the requirements for safety and security of the transmitted information so such systems are not protected against unauthorized access. The information transmitted is strategically important for performing air traffic management tasks on the territory of the Russian Federation. Unauthorized access can result in intercepting and spoofing the coordinate information of aircraft location. This is possible only in exceptional circumstances which lead to reduction in flight safety and transition of flight incidents to flight accidents. The security of transmitted information can be improved by applying noise-like signals which ensure better security indexes of transmitted signals and possess higher jamming resistance. A new LoRa technology of transferring data is widespread nowadays. The technology is based on the linear frequency modulation which has been used in radar systems for several decades. The paper presents the algorithm of operating the multilateration data transfer system and its hardware-in-the-loop simulation implemented as a virtual device.

EXTRACTION OF A COMPLEX TREND OF SIGNALS IN SYSTEMS OF INTELLIGENT SUPPORT OF THE MOVEMENT OF OBJECTS

The article is devoted to the study of problems of intellectualization of control systems of moving objects to ensure their reliable operation in difficult conditions in various physical environments. Intelligent traffic support systems are developed based on the integration of measurement, computing, communication and control technologies and are designed to ensure the collection, accumulation and processing of information, determination of navigation parameters, formation of control influences, visualization of the positioning and movement trajectories of objects, monitoring of thefunctional state of objects and the state of the operating environment, etc. When restoring the lost trajectory of a moving object in the conditions of its complex movement, when approximating complex algorithms in adaptive control systems, with sudden changes in the trajectory or conditions of movement, there is a need to extract a complex trend from noiselike signals. The existing filtering algorithms do not provide acceptable efficiency, especially in conditions of limited a priori information about the nature of changes in the useful signal component.The article proposes and substantiates the use of wavelet filtering to suppress interference and extract the initial signal of a complex shape. A study of the effectiveness of extracting a complex useful signal against the background of Gaussian noise and harmonic disturbances was conducted. To process the simulated signals, wave functions of various orders from the families of Dobechies, symlets, and coiflets were used. The effectiveness of wavelet filtering was evaluated by the mean square deviation value of the selected trend and the model of the useful signal. The comparative analysis of the obtained results showed the feasibility of using the wave function of the family of symlets, which ensured the minimum value of the root mean square deviation of the selected trend from the model of the useful signal.

NEW BARKER’s COMPOSITE CODES AS MODULATION SIGNALS IN BROADBAND COMMUNICATION SYSTEMS

Background. Currently noise-like signals (NLS) are widely used and provide high level of jamming immunity and security in broadband communication systems (BСS) when transmitting confidential information in an open radio channel, especially in emergencies. Increasing the efficiency of the NLS is possible when using more advanced code structures.
 Objective. The purpose of this research is to study new Barker’s composite codes as modulation signals in broadband communication systems.
 Method. Simulation modeling based on MatLab software package and analytical calculation methods are used.
 Results. Modeling in the MatLab software package showed the possibility for using new Barker’s composite codes as modulation signals in direct spread spectrum systems but efficiency depends on code words length as well as type synchronization signal.
 Conclusions. Analysis of research results shows that the new Barker composite codes 21a, 33a, 49, 77a, 121 can be effectively used as modulation code words in broadband systems with direct spectrum expansion.

Bowtie Nanoantenna Coupled Metal-Oxide-Silicon (p-Doped) Diode for 28.3 THz IR Rectification.

Low-temperature waste heat in the infrared (IR) wavelength region offers an opportunity to harvest power from waste energy and requires further investigation in order to find efficient conversion techniques. Although grating-coupled metal-oxide-semiconductor (MOS) diode devices offer efficient conversion from low and moderate-temperature thermal sources, the integration of such diodes with a nanoantenna structure has yet to be explored. We propose a bowtie nanoantenna coupled with a p-doped MOS diode for IR to direct current (DC) conversion without any bias voltage at 28.3 THz. The nanoantenna was designed and optimized to provide maximum field enhancement in a 4 nm-thick oxide layer at the resonant frequency. The device was fabricated following the complementary MOS (CMOS) fabrication process and measured in a custom DC and optical characterization setup using a 10.6 μm wavelength CO2 laser. The results reveal two different types of devices with linear and nonlinear I-V curves having kΩ and MΩ zero-bias resistance, respectively. The linear device generates a micron-level open-circuit voltage (Voc) with clear polarization dependence from the laser input, but the nonlinear case suffers from a weak noise-like signal. Finally, we analyze two types of devices using thermoelectric and tunneling effects and discuss the future direction of nanoantenna-integrated MOS devices for efficient IR harvesters.

Влияние нестабильной во времени частотной модуляции тональных компонент спектра шумоподобных сигналов на их различение и классификацию дельфинами Tursiops truncatus

The article is devoted to the study of the location capabilities of dolphins, which has a great practical focus associated with the country's defense capability, its security in the sea. The proposed task was gradually complicated by the distortion of the initial signals and the destruc-tion of information signs in the spectrum during the process of studying the ability of dolphin`s to recognize classify noise-like signals. The tonal components of the presented signals spectrum were unstable in both frequency and time in the study. It was shown that the added instability over time, although it leads to a slight decrease in the recognition efficiency, is not a serious obstacle for the dolphin`s auditory system. An analysis of the capabilities and nature of the cetacean biolocator creates the possibility of solving a number of technical and defense prob-lems.

Security Energy Efficiency Analysis of Analog Collaborative Beamforming With Stochastic Virtual Antenna Array of UAV Swarm

To extend the transmission range governed by limited transmit power, collaborative beamforming (CB) can be employed with a virtual antenna array (VAA) constructed by an unmanned aerial vehicle (UAV) swarm. CB techniques combined with physical layer security (PLS) algorithms are known to better secure transmissions of sensitive information in the presence of eavesdropping attacks, compared to co-located antenna-based schemes. In particular, analog collaborative beamforming (ACB) with random VAA topologies, which is suitable for UAV networks due to its lower signaling/channel estimation overhead compared to the digital CB, can provide a significantly higher secrecy rate by creating noise-like signals at eavesdroppers. However, the increase in energy consumption to improve secrecy rate had been ignored in the existing ACB-based PLS schemes, which is of paramount importance considering the limited onboard energy of UAVs. Thus, motivated by such limitation, in this paper, we examine the security energy efficiency of the ACB-based PLS technique, where a group of UAVs (or VAA elements) randomly change their locations in a distributed manner to randomize the array factor of the VAA, i.e., a stochastic VAA. The proposed stochastic VAA outperforms the existing static VAA in terms of secrecy energy efficiency as verified by analytic and numerical results. Further, the impact of phase errors of the proposed scheme is also presented, which indicates the significance of the accurate phase estimation.

Influence of Continuous Wave Interference on the Efficiency of the Non-Threshold Search Procedure for a Noise-Like Signal by Delay Time with Transition to the Frequency Domain

Influence of Continuous Wave Interference on the Efficiency of the Non-Threshold Search Procedure for a Noise-Like Signal by Delay Time with Transition to the Frequency Domain

Radio-Frequency Interference Estimation for Multiple Random Noise Sources

As more compact designs and more assembled function modules are utilized in modern electronic devices, radio-frequency interference (RFI) source reconstruction is becoming more challenging because different noise sources may contribute simultaneously. This article presents a novel methodology to reconstruct multiple random noise sources on a real-world product, including several double-data-rate (DDR) memory modules and a high-speed connector. The DDR modules located beneath a heatsink cause random noise-like signals, which renders phase measurements challenging. An approach based on the tuned-receiver mode of a vector network analyzer is developed to measure the field phase from the random DDR signals, which can be further modeled with a Huygens’ box using the measured field magnitude and phase. Moreover, the connector can be modeled using an equivalent magnetic dipole. Furthermore, the total RFI power from the DDR memory modules and the high-speed connector, which generate uncorrelated RFI noise, is found to equal the summation of the individual power values obtained by an root mean square detector, which can be mathematically corroborated. Using the proposed method, the reconstructed source model can predict RFI values close to measurement results with less than 5 dB deviation.

Application of stochastic programming method for analysis of semiconductor noise signal generators

In this work it is proposed to use the method of stochastic programming to obtain the values of key parameters of electronic components of electrical circuits, which are used to prevent leakage of confidential information due to electromagnetic radiation. The essence of the application of this method is to determine the optimal value of the power of the output noise-like signal generated by the noise generator, which provides the highest quality of interference aimed at suppressing a dangerous signal, the leakage of which is possible due to the side electromagnetic radiation at the object of information activity. The purpose of the article is to determine the condition of optimal generation of noise-like signals of semiconductor elements with specified characteristics and to optimize the maximum output power of the noise signal. Results: The article shows the use of linear and stochastic programming methods to estimate the required parameters of the noise generator by the criterion of the maximum output power of the noise signal at the load resistance. Conclusions: the conducted stochastic optimization showed the relationship of the output random variable from the initial conditions imposed on the semiconductor element, and allowed to obtain fixed optimal values of the load resistance parameters for a given optimization criterion. If we impose an additional condition of a given accuracy on the solution of this problem, we can significantly improve the quality of control of the parameters of the noise semiconductor element. Further research can be directed to determine the distribution of a random noise signal at the output of the device to counteract information leakage through the channel of side electromagnetic radiation and interference, that is, at the output of the power amplifier of the generator-jammer, to which the antenna is connected.

Шумоподобные сигналы и их преобразование, используемые в системах радиосвязи

The actual problem of determining the principle of the transmission signal formation and its transformation into an initial signal providing stable radio communication in a radio interference situation is considered. This is typical when organizing the management of fire extinguishing units, especially in forests and steppes. The subject of the study is the use of a reprogrammable matched filter (PPSF), in which a spin echo processor with a working substance 59Co is used to convert phase-manipulated noise-like signals. The purpose of the work is to propose the use of a spin processor in the PPSF, which ensures the conversion of FM SHPS even in the presence of dynamically changing multipath. With this configuration of the radio-transmitting device, it becomes possible to organize multicast radio communication without deploying a base station. The results of the study include the results of machine modeling of the conversion of FM SHPS to PPSF under unfavorable conditions of formation of a three-beam signal at the input of a radio receiver. The structural diagrams of the FM SHPS and PPSF shaper of the laboratory installation on which the research was carried out are given. The obtained results of laboratory studies within the permissible error, when removing the results and in measuring instruments coincide with the results of machine modeling. Therefore, the considered principle of converting FM SHPS into PPSF, which is based on the principle of converting FM SHPS into a primary signal, can be successfully implemented in radio stations used by units of the Ministry of Emergency Situations of Russia in fire extinguishing areas.

Detector of noise-like signals, not giving false detections associated with the correlation properties of phase-modulating signal sequences

Detector of noise-like signals, not giving false detections associated with the correlation properties of phase-modulating signal sequences

The use of non-steady state noise interferences to counteract passive eavesdropping devices

The use of noise interference has become a common practice for information security. Recently appeared publications showing a potential possibility to use the noise radio frequency interference for information skimming by passive radio eavesdropping device. In particular, the vulnerability of the premises protected from eavesdropping devices is increased, if the radio frequency noising is switched on when confidential negotiations are being conducted. The use of radio noise waves energy for eavesdropping makes such devices invisible to nonlinear locators for listening devices if they activated only by noise signals. The paper shows that the use of non-steady state noise allows counteracting the unauthorized pickup of information. The analysis of non-steady state radio frequency noise effectiveness was carried out using the correlation receiver model. The correlation receiver has the highest sensitivity, and it works more efficiently with noise-like signals. It is shown that for counteracting the information pickup, it is necessary to use a noise, amplitude modulated by a random signal, whose spectrum coincides with a spectrum of a potential informational signal. Imposition a more powerful modulation noise to a weak informational signal makes impossible the information transfer. It is shown on the example of changing the power of a monochromatic signal while “beetle” transmits using steady-state and non-steady state noises, that due to the signal energy parametric redistribution over the non-steady-state noise modulation spectrum, the power of monochromatic signal is reduced by more than 10 dB compared to the transmission of the same signal using a steady-state noise. It can be concluded that the use of non-steady state noise signals for radio frequency suppression makes impossible their use for passive eavesdropping devices operation.

A Novel Measurement Scheme for Crossly-Polarized Channel Based on the Pseudorandom Codes of Analyzing the Fuzzy Function

With the rapid development of 5G communication, crossly-polarized transmitting and receiving scalable channels have received wide attention. We conduct an in-depth analysis of the 5.8 GHz horizontal and vertical crossly-polarized electromagnetic (EM) wave propagation and propose a novel test scheme for the feature of the particular EM wave propagation. The scheme acquires the channel characteristics and the interchannel coupling interference strength by transmitting and receiving pseudorandom codes and analyzing the fuzzy function of the corresponding noise-like signals. We then optimize the pseudorandom codes with parallel pseudorandom sequence generation method based on Hash function, greatly reducing calculation time. The transceiver’s mode adopts time division duplexing and chooses the pseudorandom codes as the system transceiver’s pseudorandom codes. The fuzzy function analysis and processing are performed by a MATLAB code and we can clearly obtain pin-shaped fuzzy images and coupling interference between crossly-polarized channels.

Parameter identification of oscillations in power systems based on improved variational modal decomposition and HTLS-adaline method

Oscillation has become one of the important problems faced by modern power grids. Multi-types of oscillations may occur simultaneously in the power system and the oscillation frequency span is extremely large. For signals with wide-band oscillation modes, the signals in different frequency bands are first separated by a band-pass filter, and then the Improved Variational Mode Decomposition (IVMD) method with high noise robustness is used to extract each oscillating mode signal. Finally, the combinations of Hankel total least squares (HTLS) and adaptive neural network algorithm (Adaline ANN) is used to estimate the frequency, attenuation factor, amplitude and phase of low-frequency oscillations. Furthermore, the introduction of Adaline neural network solves the problem that the mode amplitude and phase are difficult to determine after IVMD processing, so that the detection accuracy is improved. Simulation and case analysis show that this method can effectively distinguish and extract different types of oscillation modes in the signal, and accurately identify the information of each mode. The IVMD-HTLS-Adaline method can effectively identify signals that have experienced severe oscillations or noise-like signals with potential oscillations.

Стохастизация СВЧ колебаний в микрополосковой логопериодической антенне-генераторе в условиях модуляции низкочастотным шумовым сигналом.

Microwave solid-state oscillators of noise-like signals are of the great interest for wireless telecommunication systems, imaging systems and electronic warfare. In the paper, the possibility of power combining in the array of three independent noise-like oscillators is investigated. The noise-like oscillators are based on the microstrip log-periodic antennas which are integrated with field-effect transistors. As an active element, NE350184С field-effect transistor with 13.5 dB gain at 12 GHz is chosen. It was previously shown that single-frequency, multifrequency or noise-like generations are possible in the active antennas. The main factors that affect the generation type are the current in the drain-source circuit of the transistor and the distance between the antenna plane and reflecting screen. It is experimentally shown, that using of the noise-like oscillator arrays makes possible the spectrum and power combining, but the construction is not enough stable and reliable.

Resonant Airborne Acoustic Emission for Nondestructive Testing and Defect Imaging in Composites

A new version of an acoustic emission mode which is different from its traditional counterpart is discussed in view of applications for nondestructive testing. It is based on the effect of acoustic waves generation from the defect area in ambient air by local standing wave vibration developed in this area at the defect resonant frequency. Another approach which does not require preliminary knowledge of local defect-resonance frequency is one that uses wideband acoustic activation by a noise-like input signal. The acoustic emission field from the defect area is a “fingerprint” of the radiation source, and thus is applicable to defect detection and imaging. This enables the use of commercial microphone scanning for detecting and imaging various defects in composites. An improvement in the acoustic-emission scanning mode based on a multiple-axis robot is studied to applications to complex shape components. A rapid, full-field imaging of the acoustic-emission field is implemented by means of an array of microphones (acoustic camera). Numerous case studies validate the potential of the resonant acoustic-emission modes for integration in the defect imaging system based on inexpensive, fully acoustic instrumental components.

Musical Mix Clarity Prediction Using Decomposition and Perceptual Masking Thresholds

Objective measurement of perceptually motivated music attributes has application in both target-driven mixing and mastering methodologies and music information retrieval. This work proposes a perceptual model of mix clarity which decomposes a mixed input signal into transient, steady-state, and residual components. Masking thresholds are calculated for each component and their relative relationship is used to determine an overall masking score as the model’s output. Three variants of the model were tested against subjective mix clarity scores gathered from a controlled listening test. The best performing variant achieved a Spearman’s rank correlation of rho = 0.8382 (p < 0.01). Furthermore, the model output was analysed using an independent dataset generated by progressively applying degradation effects to the test stimuli. Analysis of the model suggested a close relationship between the proposed model and the subjective mix clarity scores particularly when masking was measured using linearly spaced analysis bands. Moreover, the presence of noise-like residual signals was shown to have a negative effect on the perceived mix clarity.

Mutual Interference of Automotive OFDM Radars—Analysis and Countermeasures

Due to its noise-like signal property, digital orthogonal frequency-division multiplexing (OFDM) radars are often assumed to be robust against interference. While a lot of research has been carried out for interference between different modulation schemes, the mechanisms of interference from OFDM to OFDM radars have been barely addressed. This paper provides a thorough analysis of mutual OFDM to OFDM interference based on radar measurements using a 4x4 77 GHz multiple-input multiple-output (MIMO) OFDM radar prototype. The effects of interference are described both qualitatively and quantitatively for cyclic-prefix and stepped-carrier OFDM. Second, it is shown that conventional mitigation methods in the spectrogram are not suitable due to the random coding of cyclic-prefix OFDM. As an alternative, the application of adaptive beamforming is proposed and two realization possibilities are provided. Finally, new mitigation strategies in the modulation domain are proposed. They allow to shape interference to specific range-Doppler cells, yielding an interference-free range-velocity map for the area of interest. Additionally, the method may be used as the basis to enable simple conventional interference mitigation strategies.

NOCFASS: Quantitative description of the seismic noise-like signals in the earthquake-prone areas

Non-Orthogonal Combined Fourier Analysis of the Smoothed Signals (NOCFASS) helps to extract the reduced/invariant spectrum from the total Fourier-spectrum that contains a small number of frequencies with the linear dispersion law Ωk = a⋅k + b. The paper presents a new technique to treat original data of natural processes like seismic ambient noise, measured by the seismic gradient system with geophones on the surface. The authors show an example of the signal processing (July 14th-16th 2018) in the Ukok-2 point located in Tien Shan. A wide set of signals with a trend that is obtained from the set of initial trendless sequences (TLS) by means of integration procedure. This selected spectrum with eliminated high-frequency components is considered as an invariant spectrum, which contains only the basic low-frequency modes. The results are useful for the further detection of different random factors that disturb the TLS behavior.

Improved Unmanned Aerial Vehicle Noise Direction Finding System

The work is devoted to the development of the acoustic direction of creation of means of detection of unmanned aerial vehicles (UAVs). The work of these tools is based on the principles of noise direction finding with the use of such variable characteristics of the acoustic field as: sound intensity, frequency spectrum and spatial spectrum. The architecture of UAV detection devices on the acoustic field corresponds to the algorithms of reproduction in separate paths of the device of ideology of registration and control of dynamics of change of characteristic of an acoustic field which defines the specified change as the fact of detection. The technical implementation of the above detection devices is to create a path of parallel octave, ½ octave and ⅓ octave filters, a path of narrowband filtering and a path of detection by power (intensity). 
 The ideology of construction of detection devices is based on variability and physical manifestations of changes in such characteristics of acoustic noise as: sound intensity in the space - time interval of observation, broadband filtering, narrowband filtering, correlation characteristics.
 To ensure the detection of acoustic power (or intensity) with subsequent measurement of the level, the counter-inclusion (by switching or using operational amplifiers) of the elements of the cross-shaped group is used. An important and new feature is that one of the linear discrete acoustic antennas with an enlarged base additionally has two more pressure receivers symmetrically relative to the phase center.
 For broadband filtration, a comb of ⅓ octave band and semi-octave filters is used. In turn, the path of the narrowband spectrum is an octave band filter and a unit for calculating the fast Fourier transform.
 The path of the correlation direction-finding method implements the determination of changes in the autocorrelation coefficient and the corresponding electrical parameter (say the current through the display circuit) in the processing path in situations of fixing the direction to the target.
 Therefore, the proposed system for detecting useful noise signals should contain four paths, the physical implementation of detection in which is performed by software implementation of detection algorithms and, threshold processing and indication of results
 In order to improve and increase the reliability of detection, the direction finder is supplemented by the path of detection on the mutual spectrum and the path of the correlation method of direction finding.
 The processing of input acoustic information of the type of specific noise-like signal is carried out by using the instrumental laboratory software package Lab View and Math Lab. We will add that the article contains theoretical and practical results of measurements of noise loading and range of action of a noise direction finder. Experimental studies in terms of detection and measurement of the main characteristics of the device were conducted in laboratory and field conditions.
 At the same time, the present demonstrates the rapid development of the UAV fleet, which determines the urgency of the work and the development of the device as a means of counteracting small aircraft of various recognitions is its goal.