Signal Reception Research Articles

Investigation of Noise Immunity of Optimal Symbol Reception of Frequency-Efficient Signals with Correction Coding in Non-Binary Galois Fields

Investigation of Noise Immunity of Optimal Symbol Reception of Frequency-Efficient Signals with Correction Coding in Non-Binary Galois Fields

On measurements of spurious components of heterodyne signal in radiometric receivers

With a heterodyne frequency conversion, a significant contribution to the intrinsic noise of the radiometric receiver is made by a heterodyne. The spectral components generated by the heterodyne will be present in the processed signal at the output of the radiometric receiver and may manifest themselves when analyzing the received signal in spectral lines when high frequency resolution is required for processing. The purpose of the work is to analyze various types of modulation of the heterodyne signal, including modulation with an arbitrary phase shift between the components in the lower and upper side bands of the heterodyne signal. In this article, the methods of frequency transfer used in determining the spectral composition of the signal received by a radiometric receiver are considered. For heterodyne frequency conversion, in addition to the classical types of parasitic modulation of the heterodyne signal described in the literature – amplitude, phase (frequency) and single-band modulation, modulation with an arbitrary phase shift between the components in the lower and upper side bands of the heterodyne signal is considered. It is shown that with a small deviation of the frequencies of the modulating signal, ambiguity is possible in determining the level of components when using signal analyzers to measure the characteristics of heterodynes of radiometric receivers. The results of the analysis performed in the article can be used in the design of heterodynes with multiple output frequencies, taking into account the spectral comtent of the synthesized signal. The study was carried out at the expense of the grant of the Russian Science Foundation No. 22-19-00063 dated 13.05.2022. https://rscf.ru/project/22-19-00063.

Method of correlation reception of radio light with spatial resolution and its implementation

A method for receiving ultra-wideband noise-like microwave radiation -- radio light is considered, based on the correlation reception of signals coming from spaced apart space of receiving antennas, for the purpose of further effective image formation radio-illuminated environment. A mathematical model has been developed to study the formation possible response of the receiving system and assessing the influence of signal accumulation time on its dynamicrange. One-dimensional responses of the correlation receiving system to point sources of radiation were obtained, for which radio light sources were used. An experimental model of a correlation radio light receiver was developed and physical experiments were carried out with it, confirming the results obtained during modeling, as well as the overall performance of the proposed approach.

Interference Analysis of Coexisting 5G Networks and NGSO FSS Receivers in the 12-GHz Band

Despite the promising attributes of the 12 GHz band for expanding terrestrial 5G network’s capacity and coverage, interference between coexisting networks remains a major issue. This paper develops a simulation-based evaluation framework and investigates the harmful interference between the 5G radio links and incumbent fixed non-geostationary satellite orbit (NGSO) fixed satellite services (FSS) receivers of the 12 GHz band. A variety of features including actual deployment locations of 5G base stations (BSs) and fixed NGSO FSS receivers, industry-standardized beamforming at BSs, directional signal reception at FSS receivers, realistic propagation channels with obstruction from buildings, and channel scheduling at 5G BSs are incorporated in the interference study. Simulation results conducted in a realistic urban-micro deployment scenario confirm that the terrestrial 5G networks with directional BSs can coexist in the 12GHz band by suitably selecting exclusion zone’s radius around the FSS receiver. Simulation results also show that interference in the coexisting network can be notably reduced by appropriately activating BSs in the 12 GHz band based on their locations and surroundings.

Weak Radio Frequency Signal Reception Sensitivity Based on DC Superconducting Quantum Interference Devices

Superconducting quantum interference devices (SQUIDs) are promising for detection of extremely weak power regimes for the Internet of Things (IoT) and long-distance satellite networks. In low-frequency magnetic signal measurements, it has demonstrated superior performance over traditional systems. We review the resistively-and-capacitively-shunted junction (RCSJ) model of DC SQUIDs and investigate its transfer function to magnetic flux signals while taking thermal fluctuation into account. We numerically evaluate the influence of bias current and bias flux signal to determine the operating parameters of the device. The performances related to SQUID ring inductance operating at 4.2 K and 77 K are demonstrated. Combined with common radio frequency (RF) front-end modules, including low-noise amplifier (LNA) and low-pass filter, we evaluate the bit-error-rate (BER) performance of the system under different inductance values and inferred that the sensitivity of the system can reach -99 dBm at 100 MHz bandwidth.

Modern Methods of Sound Propagation Modeling Based on the Expansion of Acoustic Fields over Normal Modes

A review of modern methods of modeling acoustic fields based on their representation as a superposition of normal modes is presented. Most of the described methods are based on an approach to calculating mode amplitudes by solving parabolic equations of various types, both narrow-angle and wide-angle. We also consider two-dimensional methods for calculating acoustic fields, to which the above-mentioned three-dimensional approaches are reduced in the absence of dependence of the field and medium parameters on one of the horizontal coordinates. The computation of both time-harmonic acoustic fields and pulsed sound signals is discussed. A number of numerical examples are considered in which such calculations are performed taking into account three-dimensional sound propagation effects. For the first time within the framework of this approach, the calculation of particle accelerations at the pulse signal reception points, as well as the calculation of the energy density flux of the vector field were performed.

Радиооптический навигационный лунный маяк-пенетратор: возможные проектные решения

The paper presents proposals to create a lunar radio-optical navigation beacon based on the light-emitting diodes with the selenodesic reference points. Introduction of the semiconductor emitters in the infrared (0.85 microns) and ultraviolet (0.24 microns) ranges makes it possible to improve reliability in the beacon signal reception and take the measurements both in the day and nighttime intervals. As a device in creating such beacons, the paper proposes to use a two-component penetrator equipped with a thermoelectric generator to convert thermal energy into the electrical energy due to the temperature gradient in the lunar regolith and a heat pipe connecting the penetrator bow and the tail parts to ensure higher heat transfer. Technology to create such a beacon system for long-term operations under the lunar environment is analyzed.

Deep Learning - Powered Radio Frequency Fingerprint Identification: Methodology and Case Study

Radio frequency fingerprint identification (RFFI) is an authentication technique that identifies wireless devices by analyzing the characteristics of the received physical layer signals. In recent years, RFFI has been significantly enhanced by deep learning. A neural network (NN) is often leveraged to predict device identity. As a data-driven approach, deep learning requires the collection of large amounts of data for NN training. In addition, the RFFI system should be evaluated on datasets collected under various conditions to assess the system's robustness. However, only a few RFFI datasets are publicly available, and there are no clear guidelines for building an RFFI testbed for data collection. This paper presents a tutorial to build both closed-set and openset RFFI systems. A LoRa- RFFI testbed is created as a case study and the implementation details are described in depth. The LoRa-RFFI testbed involves 60 commercial-off-the-shelf (COTS) LoRa development boards as devices to be identified, and a USRP N210 software-defined radio (SDR) platform for physical layer signal reception. Experiments are carried out using the implemented LoRa-RFFI testbed, and the collected datasets are made publicly available online. It is anticipated that this work can aid the research community in constructing RFFI testbeds and facilitate the development of RFFI research.

Using Software-Defined radio receivers for determining the coordinates of low-visible aerial objects

The object of this study is the process of determining the coordinates of low-visible aerial objects. The main hypothesis of the research assumed that the signals emitted by airborne systems of airborne objects that are not visible to radar stations have a greater power than the signal reflected from the airborne object. This, in turn, could improve the signal/noise ratio and, accordingly, the accuracy of determining the coordinates of low-visible aerial objects. It is suggested to use Software-Defined Radio receivers to receive such signals emitted by on-board systems of low-visible aerial objects. It was established that the main sources of signals for Software-Defined Radio receivers are signals of command, telemetry, target channels, manual control channels, and satellite navigation. It was established that an additional distinguishing feature when determining the coordinates of low-visible aerial objects is the uniqueness of their spectra and spectrograms. The method of determining the coordinates of low-visible aerial objects when using Software-Defined Radio receivers has been improved, which, unlike the known ones, involves: – the use as signals for Software-Defined Radio of signal receivers of on-board equipment of low-visible aerial objects; – the use of a priori coordinate values of a low-visible aerial object; – conducting additional spectral analysis of signals of on-board systems of low-visible aerial objects. The spectra and spectrograms of signals of on-board systems of aerial objects when using non-directional and directional antennas were experimentally determined. The experimental studies confirm the possibility of using the Software-Defined Radio receiver to receive signals from airborne equipment and improve the signal-to-noise ratio. The accuracy of determining the coordinates of aerial objects when using Software-Defined Radio receivers was evaluated. A decrease in the error of determining plane coordinates by the Software-Defined Radio system of receivers compared to the accuracy of determining coordinates by the P-19 MA radar station was established by an average of 1.88–2.47 times, depending on the distance to the aerial object

Design and construct a Yagi Antenna with Three Reflector Element to Strengthen 4G Signal in Rural Areas

Rural areas are indicated to be still difficult to reach by 4G signals due to diverse topographical conditions and uneven landscapes, especially hilly areas that weaken the signal reception level in this region. To make the 4G signal accessible in this area, a repeater in the form of an antenna is needed to strengthen the signal. In this study, a yagi antenna is designed with three reflector elements at a working frequency of 1800 Mhz 4G LTE, expected to produce a minimum gain of 12 dBi and a more focused antenna radiation to strengthen the 4G signal in rural areas. The antenna design was simulated using CST Studio Suite software, with optimized simulation results yielding a return loss of -22 dB, VSWR 1.167, and gain 12.40 dBi. From the measurements obtained, the yagi antenna with three reflector elements works well at a frequency of 1800 Mhz, with a return loss of -34.77 dB, VSWR 1.065, gain 12.96 dBi, and unidirectional radiation. With the optimal antenna parameters and the addition of three reflector elements, it's possible to increase the gain value, even though the gain increase isn't substantial, and it narrows the HPBW (Half Power BeamWidth) value. Moreover, testing the yagi antenna at 3 different distances demonstrated that the resulting gain value can enhance 4G signal speed in rural areas

A sign in space: An interdisciplinary exploration of the potential reception of an extraterrestrial signal

A Sign in Space is an interdisciplinary project by media artist Daniela de Paulis, in collaboration with the Green Bank Observatory, the National Institute for Astrophysics, the SETI Institute and the European Space Agency.The project consists in transmitting a simulated extraterrestrial message as part of a live performance, using an ESA spacecraft as celestial source. The objective of the project is to involve the worldwide search for extraterrestrial intelligence (SETI) community, professionals from different fields and the broader public in the reception, decoding and interpretation of the message. This process will require global cooperation, bridging a conversation around the topics of SETI, space research and society, across multiple cultures and fields of expertise.

Pseudolite Multipath Estimation Adaptive Mitigation of Vector Tracking Based on Ref-MEDLL

Among many indoor positioning technologies, pseudolite positioning technology has become an important supplement to GNSS. In indoor open environments, pseudolite positioning technology can usually perform high-precision positioning. However, in a complex environment, the pseudolite receiver is seriously interfered by multipath and other interference signals, which will lead to a serious decline in the observation accuracy, signal lock loss or even no positioning results. Therefore, this work proposes a pseudolite indoor anti-multipath receiver based on reference multipath estimating delay lock loop (Ref-MEDLL). It adds the Ref-MEDLL multipath estimator module and the multipath mitigation module to the traditional receiver signal processing architecture. In the multipath mitigation module, the multipath estimation adaptive mitigation of vector tracking (MEAM-VT) method and the multipath estimation direct mitigation (MEDM) method for multipath mitigation is proposed. Experimental results show that the Ref-MEDLL multipath estimation method has good adaptability to multipath signals that have different time delays and different amplitudes; both the MEDM receiver and the MEAM-VT receiver have good multipath mitigation performance. The MEAM-VT method performs better than the MEDM method in multipath mitigation and tracking, but the stability of the pseudorange observations of the MEAM-VT method is not as good as that of the MEDM method. The positioning accuracy of the MEDM receiver and the MEAM-VT receiver has been improved to different degrees in static positioning experiments and dynamic positioning experiments.

Target Tracking from Weak Acoustic Signals in an Underwater Environment Using a Deep Segmentation Network

In submarine warfare systems, passive SONAR is commonly used to detect enemy targets while concealing one’s own submarine. The bearing information of a target obtained from passive SONAR can be accumulated over time and visually represented as a two-dimensional image known as a BTR image. Accurate measurement of bearing–time information is crucial in obtaining precise information on enemy targets. However, due to various underwater environmental noises, signal reception rates are low, which makes it challenging to detect the directional angle of enemy targets from noisy BTR images. In this paper, we propose a deep-learning-based segmentation network for BTR images to improve the accuracy of enemy detection in underwater environments. Specifically, we utilized the spatial convolutional layer to effectively extract target objects. Additionally, we propose novel loss functions for network training to resolve a strong class imbalance problem observed in BTR images. In addition, due to the difficulty of obtaining actual target bearing data as military information, we created a synthesized BTR dataset that simulates various underwater scenarios. We conducted comprehensive experiments and related discussions using our synthesized BTR dataset, which demonstrate that the proposed network provides superior target segmentation performance compared to state-of-the-art methods.

Simultaneous Estimation of Azimuth and Elevation Angles Using a Decision Tree-Based Method.

This study addresses the problem of accurately predicting azimuth and elevation angles of signals impinging on an antenna array employing Machine Learning (ML). Using the information obtained at a receiving system when a transmitter's signal hits it, a Decision Tree (DT) model is trained to estimate azimuth and elevation angles simultaneously. Simulation results demonstrate the robustness of the proposed DT-based method, showcasing its ability to predict the Direction of Arrival (DOA) in diverse conditions beyond the ones present in the training dataset, i.e., the results display the model's generalization capability. Additionally, the comparative analysis reveals that DT-based DOA estimation outperforms the state-of-the-art MUltiple SIgnal Classification (MUSIC) algorithm. Our results demonstrate an average reduction of over 90% in the prediction error and 50% in the prediction time achieved by our proposal when compared to the MUSIC algorithm. These results establish DTs as competitive alternatives for DOA estimation in signal reception systems.

Mimicking dam upstream slope scenarios in acrylic tanks for ultrasonic evaluation

Monitoring to support the integrity of structures immersed in water has been a challenge for dam engineers and other construction technicians for decades. In addition, it is known that the planning and execution of these activities are often linked to high costs and risk assessment. Non-destructive methods can act in these tasks with the production of useful information for a more optimized decision making. Ultrasound (US) is a wellknown tool that works with the emission and reception of wave signals. US stands out mainly for providing low radiation to operators, high resolution and flexibility in defining sensor arrays. Data acquisition can be performed even in immersed and tilted geometry environments. This article presents benchtop measurements from an approach focused on the microscale study of upstream slopes of earth dams. The model was developed to simulate the approximate geometry and composition of a dam slope. Traditional ultrasonic acquisition techniques are applied using immersion transducers. The investigations carried out in a model with dimensions of 30 cm, 30 cm and 100 cm, rip rap under 2H:1V inclination, central frequency of the transducer of 2.25 MHz and depth of water for measurement of up to 20 cm, demonstrated the ability to classify the ultrasonic reflection in contact between water and the different types of interfaces that mimic typical dam materials. Lessons learned from this microscale development should be tested in a controlled reservoir model before moving to field applications. The perspective of this study is to generate information capable of composing a database for machine learning and subsequently assist in decision-making for engineering solutions that act in maintenance, safety and predictive interventions in dam bodies.

New approaches to the development of information security systems for unmanned vehicles

<span>A new approach to ensuring information security is proposed for using in the zone of direct radio visibility. The approach is based on a direct analogy between radio and optical radiation. In the latter case, information protection can be ensured by identifying the point or direction from which the signal comes; all other light sources are cut off by the observer. It is shown that a similar method of information protection can also be implemented in the radio range, which corresponds to modern trends in the development of radio holography. The simplest scheme for detecting the direction to a transmitter, identified as “friend” is presented. Its operability is demonstrated by means of simulation modeling. Ways for the further development of this approach are determined, based on the fact that modern technologies make it possible to implement distributed reception of a radio signal (to use a relatively large number of receivers), which makes it possible to implement direct analogues of such optical elements as a lens, holograms.</span>

A portable transmitter based on permanent magnets for low-frequency communications in multi-scenario with complex media

There are various advantages of low-frequency (LF) wireless communications such as stable propagation characteristics and low transmission attenuation, especially in lossy media. However, conventional LF especially ELF (extremely low frequency) transmitters have the bottleneck of excessive size and power consumption. Hence, this work proposes an LF signal transmitter based on rotating permanent magnets with miniaturization and portability to address the problem. Firstly, a theoretically analytical model of the transmitter’s radiation performance considering size factors and different working methods is established, which provides a more accurate model for the calculation of the magnetic field around the transmitter. Then, a prototype is developed and a test platform is established. Finally, this work explores the potential to apply the proposed rotating magnet-based transmitter (RMBT) in various industrial scenarios. The communication experiments in multi-scenario with complex media are conducted in this work, which completed LF signal transmissions and reception in 20 m air-seawater path (the deepest depth of underwater path in this field up to date). The results verify that RMBT is capable of communication in complex media and different electromagnetic environments, especially under harsh electromagnetic conditions (such as seawater, coal and concrete). RMBT proposed in this work provides a novel strategy for the next research of LF communications in the undersea and underground scenarios.

Achieving Successful VLC Signal Reception Using A Rolling Shutter Image Sensor While Driving at 40 km/h

Achieving Successful VLC Signal Reception Using A Rolling Shutter Image Sensor While Driving at 40 km/h

The sound production of Aplodinotus grunniens in the presence of boat sounds.

Archived soundscape data from Lake Champlain, New York, were used to examine the effect of anthropogenic sounds produced by recreational boating on freshwater drum (Aplodinotus grunniens) soniferous behavior. Drum progressed from sporadic calling during the day to calls that increasingly overlapped culminating in a chorus in the late afternoon and evening. The response of drum to boat noise appeared to differ among these states, perhaps reflecting differences in the underlying behaviors. In response to boat noise, freshwater drum spawning choruses occurred later in the day, thus avoiding the noisiest periods. The peak frequency and knock rate of calls also increased in the presence of boat noise. Of the acoustical adjustments observed, the most strongly shown were those which increased the likelihood of signal reception, suggesting a Lombard effect response. Therefore, these data suggest freshwater drum have plasticity in their acoustical behavior, potentially shifting chorusing time, and altering sound characteristics to optimize communication in the presence of anthropogenic noise. However, additional work is needed to further clarify the response of freshwater drum to anthropogenic noise.

Information Fusion for Radar Signal Sorting with the Distributed Reconnaissance Receivers

The conventional method of centralizing information fusion is commonly employed for sorting radar signals in reconnaissance receivers. However, challenges arise when the distance between reconnaissance receivers and the fusion center is distant, or when the fusion center is compromised by hostile forces. To address these issues, this paper proposes a novel distributed information fusion method. In this method, each reconnaissance receiver is restricted to accessing adjacent nodes within an undirected graph for information transmission and local computation. The distributed Dempster’s combination rule and the cautious conjunctive rule are implemented using weight functions and consensus algorithms. Furthermore, an innovative outlier detection algorithm is incorporated into the fusion process to enhance its robustness. Experimental results demonstrate that the proposed method effectively improves the accuracy of radar signal sorting. When the sorting accuracy of a single reconnaissance receiver is equal to or higher than 60%, both fusion rules achieve a sorting accuracy of 100%. Even when the sorting accuracy of a single reconnaissance receiver is as low as 50%, the fused result still maintains a sorting accuracy of over 97%.