Signal Reception Research Articles

500 Mbps high-speed high-sensitivity photon-counting communication demonstration system

We propose and demonstrate a high-speed, high-sensitivity photon communication system based on a 16-pixel superconducting nanowire single-photon detector (SNSPD) array. This system integrates high-speed transmission of narrow optical pulses and multi-channel array high-speed signal detection and reception. By incorporating the proposed channel log-likelihood ratio correction and high-speed slot synchronization algorithm, the system's performance is enhanced. Experimental results demonstrate that the system exhibits leading photon sensitivity and high-speed communication performance. It achieves a post-decoding bit error rate (BER) better than 10−7 at an effective information transmission rate of up to 500 Mbps, with an incident sensitivity of 1.78 photons/bit and a detection sensitivity of 0.97 photons/bit. Furthermore, the system is capable of maintaining closed-loop BER performance within a dynamic range of at least 1.8 dB above this incident signal level, highlighting the advanced performance and reliability of the entire system. Additionally, the system supports 10 G/40 G ethernet interfaces, enabling inter-board timestamp data transmission from the time-to-digital converter (TDC) to the FPGA at rates between 300 million and 1.2 billion timestamps per second, indicating potential for rapid real-time hardware implementation. This demonstration system can provide insights for the design of future high-speed real-time photon counting communication systems.

Brain activation patterns and dopaminergic neuron activity in response to conspecific advertisement calls in reproductive vs. non-reproductive male plainfin midshipman fish (Porichthys notatus).

The plainfin midshipman fish (Porichthys notatus) relies on the production and reception of social acoustic signals for reproductive success. During spawning, male midshipman produce long duration advertisement calls to attract females, which use their auditory sense to locate and access calling males. While seasonal changes based on reproductive state in inner-ear auditory sensitivity and frequency encoding in midshipman is well documented, little is known about reproductive-state dependent changes in central auditory sensitivity and auditory neural responsiveness to conspecific advertisement calls. Previous research indicates that forebrain dopaminergic neurons are preferentially active in response to conspecific advertisement calls and during female auditory-driven behavior in the breeding season. These dopamine neurons project to both the inner ear and central auditory nuclei and contribute to regulation of inner-ear auditory sensitivity based on reproductive state. The present study tested the hypothesis that exposure to the male advertisement call would elicit differential activation in auditory brain nuclei and in the forebrain auditory-projecting dopaminergic nucleus in reproductive vs. non-reproductive male midshipman. Fish were collected during the spring reproductive and winter non-reproductive months and were exposed to a playback of the advertisement call or ambient noise (control). Immunohistochemistry identified activated neurons (pS6-ir; proxy for neural activation) in midbrain and forebrain auditory and dopaminergic nuclei. Our results revealed that in key auditory and dopaminergic areas, the greatest activation (most pS6-ir cells) occurred in reproductive males exposed to the advertisement call.

A Novel Weak Signal Reception Algorithm Integrating Soft-Limiter with Adaptive Stochastic Resonance in Alpha-Stable Distribution Noise Environments

A Novel Weak Signal Reception Algorithm Integrating Soft-Limiter with Adaptive Stochastic Resonance in Alpha-Stable Distribution Noise Environments

All-Fiber Multicomponent Gas Raman Probe Based on Platinum-Coated Capillary Enhanced Raman Spectroscopy.

This paper presents a compact all-fiber multicomponent gas Raman probe using a dual-fiber architecture within a platinum-coated capillary. The probe eliminates the need for conventional optical components like filters and dichroic mirrors by strategically employing metal coating on the excitation fiber's surface to suppress interference signals. A detailed analysis of the silica Raman signal and fluorescence propagation within the system facilitated this design. Metal-coated capillary (MCC), produced via atomic layer deposition (ALD) of platinum on silica capillaries, exhibits excellent optical properties and environmental resilience, boosting gas Raman signal reception. Careful alignment of the dual fibers relative to the platinum-coated capillary optimizes signal-to-noise ratio enhancement. The system achieves detection limits of 21 ppm for CH4, 30 ppm for C2H4, and 51 ppm for C2H6 within 45 s of exposure, alongside a rapid response time of 25 s (relative to systems based on hollow-core antiresonant fibers) and robust stability. Its streamlined optical path and compact design enhance practicality across diverse fields, including agriculture, industry, environmental monitoring, and healthcare, advancing multicomponent gas detection technology.

Statistical-based detection of pilot contamination attack for NOMA in 5G networks

Fifth-generation (5G) communication technologies, such as millimeter wave communication, massive multiple-input-multiple-output and non-orthogonal-multiple-access (NOMA) are playing a pivotal role in promoting the modern applications of the Internet-of-Things. Using non-orthogonal resource allocation, NOMA can increase spectrum efficiency and achieve wide connectivity with low transmission delay and signaling cost. Despite the high potential of NOMA in 5G communications, NOMA is susceptible to a pilot contamination attack (PCA), in which an attacker resents the same pilot signals as authorized users. Currently, using the available detection methods in NOMA gives high false positive probability since the time-division-duplex or orthogonal resource block can be allocated by many authorized user. Since the pilot contamination attack changes the signal reception at the legitimate receiver, this work introduces a novel detection scheme for identifying Pilot Contamination attack (PCA) that statistically investigates the asymmetry in received signal power levels. The main idea of the proposed detection scheme is to use various statistical measurements for normal traffic attributes (CSI) as a reference profile. Then, compute the Mahalanobis distance between the reference profile and CSI for the incoming connection and use the probability of the uniform distribution to make the final detection decision. The performance of the proposed detection technique in terms of its detection rate and false positive probabilities has been evaluated through extensive simulation. The simulation results show that the proposed scheme succeeded in detecting the pilot contamination attack with a detection rate of up to 98% and a precision reached 97.88%.

Photonic-frequency-interleaving-enabled broadband receiver with high reconfigurability and scalability

The photonic frequency-interleaving (PFI) technique has shown great potential for broadband signal acquisition, effectively overcoming the challenges of clock jitter and channel mismatch in the conventional time-interleaving paradigm. However, current comb-based PFI schemes have complex system architectures and face challenges in achieving large bandwidth, dense channelization, and flexible reconfigurability simultaneously, which impedes practical applications. In this work, we propose and demonstrate a broadband PFI scheme with high reconfigurability and scalability by exploiting multiple free-running lasers for dense spectral slicing with high crosstalk suppression. A dedicated system model is developed through a comprehensive analysis of the system non-idealities, and a cross-channel signal reconstruction algorithm is developed for distortion-free signal reconstruction, based on precise calibrations of intra- and inter-channel impairments. The system performance is validated through the reception of multi-format broadband signals, both digital and analog, with a detailed evaluation of signal reconstruction quality, achieving inter-channel phase differences of less than 2°. The reconfigurability and scalability of the scheme are demonstrated through a dual-band radar imaging experiment and a three-channel interleaving implementation with a maximum acquisition bandwidth of 4 GHz. To the best of our knowledge, this is the first demonstration of a practical radio-frequency (RF) application enabled by PFI. Our work provides an innovative solution for next-generation software-defined broadband RF receivers.

Nexus: A versatile console for advanced low-field MRI.

To develop a low-cost, high-performance, versatile, open-source console for low-field MRI applications that can integrate a multitude of different auxiliary sensors. A new MR console was realized with four transmission and eight reception channels. The interface cards for signal transmission and reception are installed in PCI Express slots, allowing console integration in a commercial PC rack. Following standards developed by the MRI community, we implemented an open-source console software package with native Pulseq and ISMRM raw data support. It is implemented in Python to allow easy customization and provide the flexible use of a freely configurable number of transmit and receive channels. We benchmarked the system by comparing the imaging quality with a state-of-the-art reference system. Different examples of how auxiliary sensors, connected via additional channels, can improve imaging are demonstrated. Using a three-dimensional turbo spin-echo sequence, image quality of proton density-weighted and T2-weighted images in the brain of a healthy volunteer obtained by the proposed Nexus console matches closely to a commonly applied commercial system. The use of additional receive channels was demonstrated for system monitoring (radiofrequency pulses and gradient currents), electromagnetic interference detection, and temperature and B0 field monitoring. Based on these measurements, system calibrations and electromagnetic interference-mitigation techniques were applied to improve image quality. Our console offers high versatility in terms of data acquisition, is freely configurable, adheres to open-source data standards, and is easy to customize. It yields a similar image quality compared with a commercially available reference system yet is substantially lower cost and open source.

BLE Signal Reception and Localization Performance with Varying Receiver and Beacon Setups

This paper examines the performance of Bluetooth Low Energy signal reception for indoor localization by analyzing the interactions between gateways, beacons, and receiver placements. The study investigates the effect of different BLE beacon placements on signal strength and localization accuracy. It evaluates ten receiver ceiling-mounted and wall-mounted configurations, as well as five beacon body positions: shoulder, front pocket, back pocket, and wrist. A dataset comprising 2700 data points was collected and localization accuracy was assessed using a Radial Basis Function-based methodology. The results demonstrate that ceiling-mounted gateways offer more stable signal strength and enhanced localization accuracy compared to wall-mounted gateways. The findings highlight the significance of optimizing both gateway positioning and body placement to improve the performance of BLE-based indoor positioning systems.

Theoretical Proof and Implementation of Digital Beam Control and Beamforming Algorithm for Low Earth Orbit Satellite Broadcast Signal Reception Processing Terminal

Compared to analog beamforming, digital beamforming offers better self-calibration and lower sidelobe performance, which has a profound impact on improving low Earth orbit receiver performance. The Digital Beamforming (DBF) module in the low Earth orbit satellite broadcast signal reception terminal can use digital phase shifting to compensate for the phase differences caused by path and spatial distance variations due to inconsistent Radio Frequency (RF) channel delays. This compensation ensures in-phase summation, thereby achieving maximum energy reception in the desired direction. Although DBF has gained widespread attention in the radar field due to its unique functions and advantages, its application is limited by beamforming accuracy and gain. Therefore, with the development of DBF technology, how to improve its accuracy and gain has also attracted extensive attention both domestically and internationally. To address this issue, this paper proposes a beamforming method based on a cap-shaped array for low Earth orbit satellite broadcast signal reception and processing terminals. The method combines prior information and spatial domain search for beam control, and employs a lookup table for beam synthesis. It derives formulas for the Signal-to-Noise Ratio, noise figure, processing flow of the beamforming network, and the determination of beamforming weights for the spherical antenna array. The paper presents a beam control approach that combines prior information with spatial domain search, along with an implementation process for beam synthesis using a lookup table. It also details the corresponding Field-Programmable Gate Array (FPGA) implementation process. Finally, the beamforming algorithm is experimentally validated, and error analysis is conducted. The experimental results show that the measured beamforming sensitivity at all incident angles is below −133 dBm and the G/T values are all greater than −9 dB/K, the beam uniformity at three operating frequencies is less than 3°, and the measured errors in pitch and azimuth angles are both below 2°. The beam pointing error is also below 2°.

Integrating molecular photoswitch memory with nanoscale optoelectronics for neuromorphic computing

Photonic solutions are potentially highly competitive for energy-efficient neuromorphic computing. However, a combination of specialized nanostructures is needed to implement all neuro-biological functionality. Here, we show that donor-acceptor Stenhouse adduct dyes integrated with III-V semiconductor nano-optoelectronics have combined excellent functionality for bio-inspired neural networks. The dye acts as synaptic weights in the optical interconnects, while the nano-optoelectronics provide neuron reception, interpretation and emission of light signals. These dyes can reversibly switch from absorbing to non-absorbing states, using specific wavelength ranges. Together, they show robust and predictable switching, low energy thermal reset and a memory dynamic range from days to sub-seconds that allows both short- and long-term memory operation at natural timescales. Furthermore, as the dyes do not need electrical connections, on-chip integration is simple. We illustrate the functionality using individual nanowire photodiodes as well as arrays. Based on the experimental performance metrics, our on-chip solution is capable of operating an anatomically validated model of the insect brain navigation complex.

Human Trajectory Imputation Model: A Hybrid Deep Learning Approach for Pedestrian Trajectory Imputation

Pedestrian trajectories are crucial for self-driving cars to plan their paths effectively. The sensors implanted in these self-driving vehicles, despite being state-of-the-art ones, often face inaccuracies in the perception of surrounding environments due to technical challenges in adverse weather conditions, interference from other vehicles’ sensors and electronic devices, and signal reception failure, leading to incompleteness in the trajectory data. But for real-time decision making for autonomous driving, trajectory imputation is no less crucial. Previous attempts to address this issue, such as statistical inference and machine learning approaches, have shown promise. Yet, the landscape of deep learning is rapidly evolving, with new and more robust models emerging. In this research, we have proposed an encoder–decoder architecture, the Human Trajectory Imputation Model, coined HTIM, to tackle these challenges. This architecture aims to fill in the missing parts of pedestrian trajectories. The model is evaluated using the Intersection drone the inD dataset, containing trajectory data at suitable altitudes, preserving naturalistic pedestrian behavior with varied dataset sizes. To assess the effectiveness of our model, we utilize L1, MSE, and quantile and ADE loss. Our experiments demonstrate that HTIM outperforms the majority of the state-of-the-art methods in this field, thus indicating its superior performance in imputing pedestrian trajectories.

High Impedance Microstrip Resonators and Transceiver Arrays for Ultrahigh Field 10.5T MR Imaging.

Multichannel transceiver coil arrays are needed to enable parallel imaging and B1 manipulation in ultrahigh field MR imaging and spectroscopy. However, the design of such transceiver coils and coil arrays often faces technical challenges in achieving the required high operating frequency at the ultrahigh fields and sufficient electromagnetic (EM) decoupling between resonant elements. In this work, we propose a high impedance microstrip transmission line resonator (HIMTL) technique that has unique high frequency capability and adequate EM decoupling without the use of dedicated decoupling circuits. To validate the proposed technique for the ultrahigh field 10.5T applications, a two-channel high impedance microstrip array with the element dimension of 8cm by 8cm was built and tuned to 447 MHz, Larmor frequency of proton at 10.5T, for signal excitation and reception. Bench tests and numerical simulations were performed to evaluate its feasibility and performance. The results show that the proposed high impedance microstrip technique can be a simple and robust way to design high frequency transceiver coils and coil arrays for ultrahigh field MR applications.

Impact of Radial Grounding Model Granularity on Directivity of 433 MHz Monopole Antennas with Flat and Inclined Radials for ISM IoT Applications

Grounding is a critical factor in the performance of quarter-wave monopole antennas. Previous studies have explored finite, continuous grounding configurations with one- and two-dimensional variations in size for a 433 MHz vertical monopole antenna, identifying optimal geometries that maximize directivity while minimizing material costs and grounding size. However, these findings are not directly applicable to mission-critical environments (e.g., space, airborne, underwater, or ground-based applications) where continuous metallic grounding may be unavailable. This study extends the investigation to discretized grounding configurations, specifically employing radial monopoles formed by metal rods arranged in sparse or dense radial patterns. Both flat planar and inclined configurations of radial rods are analysed, with a focus on understanding the influence of design parameters, such as radial length and inclination angle, on antenna directivity and radiation patterns—key factors affecting signal reception in wireless communication systems, particularly in applications such as the internet of things (IoT). Using the Method of Moments (MoM) for simulation, the study provides practical guidelines for optimizing the design of 433 MHz monopole antennas constrained by finite and discrete grounding structures. The results indicate that an elevated radial configuration, consisting of five radials inclined at 5° from the monopole plane (equivalent to 85° from the horizontal plane) with a radial length of 2.5 meters, achieves a directivity of 9.23 dBi at 433 MHz. This represents a significant improvement over the flat planar configuration, which achieves a directivity of 6.23 dBi under the same conditions. These findings are particularly relevant for mobile communication, Internet of Things (IoT) devices, and radiofrequency (RF) systems requiring high performance from vertical monopole antennas in challenging grounding environments

Ultrasonic probes and echo time algorithms in ultrasonic gas flow measurement systems: Progress and perspectives

Ultrasonic gas flowmeters employ non-intrusive measurement techniques, characterized by rapid responsiveness and exceptional anti-interference capabilities. These attributes not only minimize disruption to the gas during measurement but also facilitate dynamic process control while ensuring robust performance under complex operational conditions. This paper provides an overview of the key components of ultrasonic gas measurement systems, briefly summarizing the fundamental principles of commonly used measurement methods. After focusing on the evolution of transducer structures and materials within ultrasonic probes, it categorizes different types of transducers and outlines the latest designs of excitation circuits in both hardware and software. The review also critically assesses the determination of echo signal reception characteristics and the accuracy and effectiveness of time-of-flight calculations. Based on innovative analyses of the critical nodes within the measurement system's components, a framework system is established for corresponding measurement scenarios. The measurement results show that the repeatability error of the new transducer remains below 0.3%. The optimized signal processing method expands the measurable flow range to 30–1200 m3/h, and the zero drift is reduced to approximately half of the system's original zero drift. This paper aims to provide clear guidance for researchers and professionals in related industries, enabling them to conduct more in-depth studies based on their research interest and enhancing their understanding of ultrasonic measurements.

Direct Position Estimation (DPE): A Potential Application in Geodetic Networks

Direct Position Estimation (DPE) is a relatively new technique in the Global Navigation Satellite System (GNSS) that is used to estimate the user’s position, velocity, and time directly from the correlation values of the received GNSS signal with the internal replica signals of the receiver. Unlike the conventional two-step approach, DPE infers the position directly from the sampled data without intermediate steps by joining signal tracking, and the navigation technique directly compares the expected signal reception of multiple potential navigation candidates against the actual received signal. The theoretical results indicate that DPE-based GNSS receivers can achieve more robust localization than conventional two-step receivers. DPE localization algorithms that compute the navigation solution directly in the navigation domain have been proposed, providing ways to address the challenges of conventional two-step receivers at the expense of additional computational load. Despite its high computational load, DPE is a more robust positioning algorithm than conventional two-step receivers in terms of multipath mitigation. The resilience of DPE against multipath and non-line-of-sight can even potentially offer applications in geodetic networks, where robust estimators are traditionally employed to counteract outliers.

A Compact Broadband Common-Aperture Dual-Polarized Antenna for Drone Applications.

A novel common-aperture miniaturized antenna with wideband and dual-polarized characteristics is proposed, which consists of a circularly polarized (CP) and a linearly polarized (LP) antenna. The circularly polarized antenna stacked on the upper layer adopts asymmetrical ground and introduces the patch and T-type feed network. On this basis, the meshed reflector structure, which also works as a ground plane for the LP antenna, is added to reduce the influence on circular polarization and achieve directional radiation. The LP antenna stacked in the lower layer uses a monopole structure, and the coaxial feed line perforates the reflector, and thereby the common-aperture antennas are tightly stacked together from top to bottom. Simulation and test are in good accordance, and the results show that the two ports of the antenna are well matched in the range of 5.5 GHz to 7.8 GHz, where peak gains of 8.5 dB and 6 dB are realized for circular polarization and linear polarization, respectively. Moreover, the 3 dB axial ratio (AR) bandwidth of the CP antenna is 34.3% and the isolation between the two ports is better than 15 dB, suggesting potential applications in the relay platform or drone detection for signal transmission and reception.

Analysis of Digital Television Signal Reception in Combined Transmitter Antenna Systems

The Indonesian broadcasting sector has undergone significant transformation with the implementation of the Analogue Switch Off (ASO) program. By July 2023, approximately 97.23% of television stations in Indonesia had migrated to digital broadcasting. However, this figure does not reflect an equitable distribution of normal broadcasts. Data from Transmission Station X indicate that 6.77% of broadcasts are blank, 12.24% experience freezing, and only 80.99% are classified as normal for channel X in the Jabodetabek region. These statistics suggest that the primary objective of the ASO program—providing an enhanced television viewing experience—has not yet been universally achieved. Therefore, efforts are required to ensure the equitable distribution of normal broadcasts. Transitioning from a lower transmitter antenna system to a combined transmitter antenna system is proposed as a potential solution. This study evaluates the Modulation Error Ratio (MER) values in the Jabodetabek region when channel X uses a combined transmitter antenna system. Measurements, conducted using the drive test method, reveal that 99.703% of MER data are above the threshold (normal broadcasts), 0.042% are at the threshold (freeze broadcasts), and 0.255% are below the threshold (blank broadcasts). These results demonstrate that adopting a combined transmitter antenna system can help address the uneven distribution of normal broadcasts in the Jabodetabek region.

PTX3-assembled pericellular hyaluronan matrix enhances endochondral ossification during fracture healing and heterotopic ossification.

Endochondral ossification (EO) is a pivotal process during fracture healing and traumatic heterotopic ossification (HO), involving the cartilaginous matrix synthesis and mineralization. Unlike the extracellular matrix, the hyaluronan (HA)-rich pericellular matrix (PCM) directly envelops chondrocytes, serving as the frontline for extracellular signal reception and undergoing dynamic remodeling. Pentraxin 3 (PTX3), a secreted glycoprotein, facilitates HA matrix assembly and remodeling. However, it remains unclear whether PTX3 affects EO by regulating HA-rich PCM assembly of chondrocytes, thereby impacting fracture healing and traumatic HO. This study demonstrates that PTX3 deficiency impairs fracture healing and inhibits traumatic HO, but dose not affect growth plate development in mice. PTX3 expression is up-regulated during chondrocyte matrix synthesis and maturation and is localized in the HA-rich PCM. PTX3 promotes the assembly of HA-rich PCM in a serum- and TSG-6-dependent manner, fostering CD44 receptor clustering, activating the FAK/AKT signaling pathway, and promoting chondrocyte matrix synthesis and maturation. Local injection of PTX3/TSG-6 matrix protein mixture effectively promotes fracture healing in mice. In conclusion, PTX3-assembled HA-rich PCM promotes chondrocyte matrix synthesis and maturation via CD44/FAK/AKT signaling. This mechanism facilitates EO during fracture healing and traumatic HO in mice.

XAI GNSS-A Comprehensive Study on Signal Quality Assessment of GNSS Disruptions Using Explainable AI Technique.

The hindering of Global Navigation Satellite Systems (GNSS) signal reception by jamming and spoofing attacks degrades the signal quality. Careful attention needs to be paid when post-processing the signal under these circumstances before feeding the signal into the GNSS receiver's post-processing stage. The identification of the time domain statistical attributes and the spectral domain characteristics play a vital role in analyzing the behaviour of the signal characteristics under various kinds of jamming attacks, spoofing attacks, and multipath scenarios. In this paper, the signal records of five disruptions (pure, continuous wave interference (CWI), multi-tone continuous wave interference (MCWI), multipath (MP), spoofing, pulse, and chirp) are examined, and the most influential features in both the time and frequency domains are identified with the help of explainable AI (XAI) models. Different Machine learning (ML) techniques were employed to assess the importance of the features to the model's prediction. From the statistical analysis, it has been observed that the usage of the SHapley Additive exPlanations (SHAP) and local interpretable model-agnostic explanations (LIME) models in GNSS signals to test the types of disruption in unknown GNSS signals, using only the best-correlated and most important features in the training phase, provided a better classification accuracy in signal prediction compared to traditional feature selection methods. This XAI model reveals the black-box ML model's output prediction and provides a clear explanation of the specific signal occurrences based on the individual feature contributions. By using this black-box revealer, we can easily analyze the behaviour of the GNSS ground-station signals and employ fault detection and resilience diagnosis in GNSS post-processing.

Unique MIMO System Using Gaussian Signals and the Advantage of These Signals in Sensing CSI and Multipath Fading

ABSTRACTTo improve communication network efficiency, researchers must look at all aspects of transmission and the mechanisms that regulate their evolution as a whole. These features include solutions for dealing with the channel's noise and interference. To decrease interference and increase spectrum efficiency, orthogonal frequency division multiple access (OFDMA) systems employ orthogonal signals. While transmitting and receiving signals, noise and numerous feeds can be done in diverse ways. It has become increasingly common to use 256 quadratic modulation (QAM), which is more vulnerable to noise and has a higher bit error rate (BER). BERs in OFDM systems were high when multiple feeds and noise were present, as demonstrated in this article. Starting with the transmission and reception of Gaussian subband signals, an improved system has been designed that includes numerous stages of development. Thus, the need for “orthogonally” of transmitted signals to increase spectrum efficiency has been eliminated, as has the effect of surrounding channels. We have created a header for every frame that has been transmitted. Several transmitters and numerous receivers send these frames in parallel so that the channel state information (CSI) attributes may be evaluated using parallel processing. Using the identical transmission conditions for both OFDM systems and the proposed system, the simulation results reveal a significant reduction in BER values. This results in BER values of fewer than 10−1 when there are two tabs and 10−1 when there are three tabs for multiple feeding in the OFDM system. This corresponds to BER values of 10−11 in a suggested system when there are three tabs. Some improvements have been made to the proposed design to make it distinctive and qualified to be regarded as a multiaccess system in today's contemporary communication infrastructures.