Radio Frequency Module Research Articles

Design of Low Noise Amplifier Based on Tuneable Active Inductor and Capacitor for Bluetooth Applications

Active components such as active inductors and active capacitors have been used to replace their passive counterparts, especially in radio frequency modules. Besides saving colossal silicon area, active inductors are power saviors, tuneable, and provide large inductance ranges. This paper presents the evaluation and performance of a low noise amplifier (LNA) implemented using only active components. The active inductor has a high inductance tunability range from 848 nH to 1660 nH, resulting in a frequency range from 1.85 GHz to 3.02 GHz. The active inductor's quality factor is 11, with a maximum power dissipation of 208.1 µW from a 0.5 V DC power supply. The LNA provides a voltage gain of 8.76 dB with a noise figure of 8.21 dB while consuming 779.16 µW from a 0.85 V supply. The achieved frequency range is commonly used for various wireless communication applications, including Wi-Fi and Bluetooth.

Influence of Opening Time Interval of Gate Signals on Suppression of Horizontally Polarized Signal of Infrared Pulsed Laser.

Since the beginning of the 21st century, infrared Nd:YVO4 pulsed lasers have been widely applied, especially in some actual industrial processes. In the working process of a laser-aided etching device, the "match-head" effect must be effectively controlled by suppressing the first giant pulse for a solid-state Q-switched laser. In the process of optimizing the infrared Nd:YVO4 pulsed laser by adjusting the slope parameters of the radio frequency (RF) modulation to suppress the first giant pulse, it has been found that an abnormal horizontally polarized emission with a very short time appears before the formal vertically polarized emission when the gate signal is artificially started. Actually, abnormal horizontally polarized emissions will bring some unexpected machining traces during the production process and even greater dangers. The experimental results show that with the increase in the slope duration of an RF signal, the existence time of abnormal output horizontally polarized light will be shortened, and the horizontal giant pulse and vertical giant pulse are well suppressed. When the slope duration is greater than 0.18 ms, both horizontal and vertical giant pulses will disappear. The horizontally polarized light can be thoroughly suppressed when the slope duration is greater than 13.7 ms. Compared with the method of adding a polarizer to eliminate abnormal output horizontally polarized light, this method does not add elements in the laser, ensuring that the laser volume is relatively small, and does not affect the quality of the normal output laser. The research conclusion is thought to be of great practical significance, especially for processing transparent materials.

Progressive Unsupervised Domain Adaptation for Radio Frequency Signal Attribute Recognition across Communication Scenarios

As the development of low-altitude economies and aerial countermeasures continues, the safety of unmanned aerial vehicles becomes increasingly critical, making emitter identification in remote sensing practices more essential. Effective recognition of radio frequency (RF) signal attributes is a prerequisite for identifying emitters. However, due to diverse wireless communication environments, RF signals often face challenges from complex and time-varying wireless channel conditions. These challenges lead to difficulties in data collection and annotation, as well as disparities in data distribution across different communication scenarios. To address this issue, this paper proposes a progressive maximum similarity-based unsupervised domain adaptation (PMS-UDA) method for RF signal attribute recognition. First, we introduce a noise perturbation consistency optimization method to enhance the robustness of the PMS-UDA method under low signal-to-noise conditions. Subsequently, a progressive label alignment training method is proposed, combining sample-level maximum correlation with distribution-level maximum similarity optimization techniques to enhance the similarity of cross-domain features. Finally, a domain adversarial optimization method is employed to extract domain-independent features, reducing the impact of channel scenarios. The experimental results demonstrate that the PMS-UDA method achieves superior recognition performance in automatic modulation recognition and RF fingerprint identification tasks, as well as across both ground-to-ground and air-to-ground scenarios, compared to baseline methods.

A Novel Transverse Ultrasound-Guided Approach for Puncturing the Cervical Dorsal Root Ganglion at the Level of Articular Pillar for Radiofrequency Treatment.

Currently, minimally invasive intervention surgery for cervical spondylotic radiculopathy mostly involves the use of cervical dorsal root ganglion (DRG) block or radiofrequency modulation therapy. Here, we proposed a novel transverse ultrasound-guided approach for puncturing the cervical dorsal root ganglion at the level of joint column for radiofrequency treatment. A retrospective analysis of the clinical data of 30 patients with cervical spondylotic radiculopathy admitted to the Pain Department of Taihe Hospital Affiliated with Hubei Medical University from January 2021 to March 2024 was performed. During surgery, motor electrical stimulation was used to induce movement in the nerve-innervated area, and the relationship between the puncture needle tip and the cervical DRG position was verified using a C-arm X-ray machine. The numerical rating scale (NRS) was used for preoperative and postoperative pain assessment, clinical treatment effectiveness was evaluated, surgical duration and the associated complications were also recorded. Thirty patients exhibited clear cervical DRG images under ultrasound guidance, and the punctures were successful in all patients. Motor electrical stimulation induced movement in the corresponding nerve innervation area in the range of 0.3-0.8 mv in all patients. No serious complications occurred during the procedure. The transverse ultrasound-guided approach for puncturing the cervical dorsal root ganglion at the level of joint column for radiofrequency treatment is effective, convenient, and safe.

SCADA System for Process Data Exchange in Master Slave RF and Iot Network

In every aspect of our lives, we can observe how automation plays a facilitating role in the performance of responsibilities of a comprehensive rank. Thanks to the development of electronics, today's process measurement systems enable the measurement values of process quantities to be visualized on display, sent remotely, and stored in a file, compatible with future user processing. In this paper are represented results of the development, design and practical implementation of the SCADA system, which enables data exchange between SCADA screen, MASTER and SLAVE stations. The MASTER station is installed in one industrial plant and the SLAVE is installed in another plant. The SCADA monitoring system is built into the MASTER station. The SLAVE station is connected by RF (radio frequency connection) to the MASTER station. In the MASTER and SLAVE station two microcomputers units, as well as appropriate RF modules, are installed. The microcomputer in the MASTER station is serially connected to the IoT microcomputer, for the transfer of measurement data in the Internet network. The solution provides visualization, data log file, and transfer to the IoT network of process data from the two industrial plants.

A Smart Farm Monitoring and Control System using Wireless Sensor Network

Agriculture is one of the most important sector that accounts for economic growth in the developing countries of the world. Many developing countries are now focusing on agricultural development, yet the sector is not without challenges including climate changes, drought, flooding to mention but a few. These result in poor yield of agricultural products. In this work, we l developed a robust smart system to enhance both irrigation and flooding monitoring and control, leveraging on Wireless Sensor Networks (WSNs) to boost agricultural production. In the system’s implementation, Arduino based instrumentation, integrated with temperature, soil moisture and water level sensor shall be adopted to monitor the agricultural environment, while reporting the status wirelessly through the Radio Frequency (RF) modules to the base station. The base station will evaluate the received data and either activates or deactivates the irrigation or drainage pump using specified threshold values. The remote reporting the state of farm shall be done by deploying a 900Mhz transmitter interfaced with the system’s controller. This work shall be validated using an experimental test bed, which shall be used for field experiments, data collection and evaluation. The result of the work shall highlight the potentials of WSN technology in monitoring and control technology of both irrigation and flooding within the farm and in turn boost productivity

Enhancing the electrical readout of the spin-dependent recombination current in SiC JFETs for EDMR based magnetometry using a tandem (de-)modulation technique

Electrically detected magnetic resonance (EDMR) is a promising method to readout spins in miniaturized devices utilized as quantum magnetometers. However, the sensitivity has remained challenging. In this study, we present a tandem (de-)modulation technique based on a combination of magnetic field and radio frequency modulation. By enabling higher demodulation frequencies to avoid 1/f-noise, enhancing self-calibration capabilities, and eliminating background signals by 3 orders of magnitude, this technique represents a significant advancement in the field of EDMR-based sensors. This novel approach paves the way for EDMR being the ideal candidate for ultra-sensitive magnetometry at ambient conditions without any optical components, which brings it one step closer to a chip-based quantum sensor for future applications.

A Wearable Real-Time System for Simultaneous Wireless Power and Data Transmission to Cortical Visual Prosthesis.

Wireless, miniaturised and distributed neural interfaces are emerging neurotechnologies. Although extensive research efforts contribute to their technological advancement, the need for real-time systems enabling simultaneous wireless information and power transfer toward distributed neural implants remains crucial. Here we present a complete wearable system including a software for real-time image capturing, processing and digital data transfer; an hardware for high radiofrequency generation and modulation via amplitude shift keying; and a 3-coil inductive link adapt to operate with multiple miniaturised receivers. The system operates in real-time with a maximum frame rate of 20 Hz, reconstructing each frame with a matrix of 32 × 32 pixels. The device generates a carrier frequency of 433.92 MHz. It transmits the highest power of 32 dBm with a data rate of 6 Mbps and a variable modulation index as low as 8 %, thus potentially enabling wireless communication with 1024 miniaturised and distributed intracortical microstimulators. The system is primarily conceived as an external wearable device for distributed cortical visual prosthesis covering a visual field of 20 °. At the same time, it is modular and versatile, being suitable for multiple applications requiring simultaneous wireless information and power transfer to large-scale neural interfaces.

Outcomes of Twice Repeated High-Voltage Long-Duration Pulsed Radiofrequency Treatment in Subacute Postherpetic Neuralgia: a Retrospective Single-Center Analysis.

The treatment of herpes zoster-related pain is challenging, and requires a variety of methods including pulse radio frequency modulation. Among them, single-time high-voltage long-term pulsed radiofrequency (HL-PRF) has been proved to be an effective treatment for subacute postherpetic neuralgia. However, it has the possibility of poor long-term curative effect and recurrence of neuralgia. In this study, we aim to identify the clinical efficacy and safety of twice repeated HL-PRF treatment in patients with subacute postherpetic neuralgia. We conducted a retrospective analysis of subacute postherpetic neuralgia patients who underwent HL-PRF treatment. Pain Management Department of First Affiliated Hospital of Wannan Medical College. We enrolled all patients with subacute postherpetic neuralgia, who underwent HL-PRF treatment from January 2023 to October 2023. The primary outcome variable was the visual Analog Scale (VAS) scores at 1, 4, 8, and 12 weeks after treatment. Secondary outcomes included Pittsburgh sleep quality index (PSQI), 36-item short-form health survey (SF-36) score, and total effective rate after treatment. A total of 63 patients were included in the analysis. Among them, 33 patients received single-time HL-PRF treatment (Group S) and 30 patients received twice repeated HL-PRF treatment (Group T). Pain scores, PSQI scores, and SF-36 score were reduced in both groups after treatment (P < 0.001). Compared to group S, the VAS scores, PSQI scores, anxiety scores, and depression scores were significantly lower at 1, 4, 8, and 12 weeks in group T. (P < 0.001). The total efficiency rate at 12 weeks after treatment of group T was statistically higher than that of group S (60.6% vs 86.7%, P < 0.05). Twice repeated high-voltage long-duration PRF therapy demonstrates satisfactory efficacy in patients with subacute postherpetic neuralgia and is associated with no significant adverse reactions.

Performance Analysis of Six Electro-Optical Crystals in a High-Bandwidth Traveling Wave Mach-Zehnder Light Modulator

In this study, a traveling wave Mach-Zehnder intensity modulator (TW-MZM) was designed and optimized for six different electro-optical (EO) crystals: lithium niobate (LNB), potassium niobate (KNB), lithium titanate (LTO), beta barium borate (BBO), cadmium telluride (CdTe), and indium phosphide (InP). The performance of each EO crystal, including optical and radio frequency (RF) loss, applied voltage, and modulation bandwidth, was estimated and compared. The results suggest that, in theory, KNB, LTO, BBO, and CdTe have the potential to outperform LNB. However, it should be noted that the loss associated with KNB and LTO is comparable to that of LNB. The findings demonstrated that BBO and CdTe exhibit a modulation bandwidth exceeding 100 GHz and demonstrate the lowest loss among the considered crystals based on the assumed geometry.

Smart AI Powered Auto Bill generation using Deep Learning and IOT

[1]. Smart shopping cart: In [1] this paper the author designed system for shopping mall. The system is placed in the trolleys. It consists of RFID reader and each product has RFID tag. The billing is done in smart trolley itself. Product name and its price display on LCD screen. At the cash counter the total bill relocated to Personal Computer by wireless Radio Frequency module. The disadvantage of this scheme is after completion of shopping, a key is pressed indicating the final promoting amount of the entire item, and we can’t add or remove the products. [2]. Innovative shopping cart:In [2] this paper the author designed system for shopping mall. In this paper they developed a smart way for shopping. In every item has RFID tag in its place of barcode scanner. The smart trolley involves of RFID reader LCD screen and ZigBee transmitter. The sum total cost of all the products will be added to the final bill, which will be kept in the microcontroller memory. Drawback of the system is in ZigBee there is distance barrier is occurred. [3]. Smart trolley using Arduino: In [3], this paper the author invented such a system it consists of RFID, ARM7, Display, Power supply, Switch, IR sensor pair, Barcode reader Visual Basics. The system works as the inventor use the barcode reader as well as RFID. And our shopping is done through the serial communication we transferred the total bill to the counter for printing the hardcopy of the product bill. There is also facility for the payment is credit card or any other. The drawback of the system is their uses both the reader RFID and Barcode Reader because of that the system becomes more multifaceted. [4]. RFID based advanced shopping trolley for super market: In this paper the author found such a system it consists of GSM, RFID, Automatic Billing, OTP, ZIGBEE, and PIC. In this scheme, the item can be read by the reader and the total of the Item is showed on the LED screen they categorized this paper because they added some additional features in the existing system like in this system the product weight and the name shown on display if item weight is less than stored weight then buzzer will beep.

Minimally Invasive Interventions on Ganglion Impar in Treatment of Patients with Coccygodynia

Chronic pelvic pain (CPP) is usually treated conservatively, but in patients who do not respond to treatment, ganglion impar (GI) interventions are used as an alternative way to reduce pain. Objective ‒ to study the course of pain syndrome and functional status in patients with coccygodynia (CD) and CPP during the application of minimally invasive interventions on GI. Materials and methods. The analysis of the results of 56 interventions on GI in 50 patients was performed. Inclusion criteria were patients with coccyx pain for ≥3 months aged 23 to 71 years (mean age 47.9±14.8years) who did not respond to conservative treatment methods. 15 (35.7%) of the study participants were male and 27 (64.3%) were female. Interventions were performed on the patients according to five different methods, which were divided into two groups: the first group (n=34) ‒ GI block (GIB) with a local anesthetic and a steroid (patients with CD in whom medical conservative methods of treatment were not effective). The second group (n=14) consisted of persons with recurrent pain syndrome, resistant forms of CD and CPP, including after previously performed steroid injections: n=2 – neurolysis of GI with ethyl alcohol; n=2 – neurolysis of GI by phenol; n=3 – radio frequency modulation of GI; n=7 – radiofrequency ablation of GI. Results. 14.0% of all study participants had post-traumatic CD (history of falling on the coccyx), the vast majority of 86.0% ‒ idiopathic CD. Pain intensity was significantly lower post-intervention compared to baseline VAS mean of 7.6±1.5 cm: 2.5±0.9 cm one-week post-procedure, 1.5±1.9 cm one month, 1.3±1.5 cm three months, 2.1±1.2 cm six months. The average score according to the Karnovsky Scale (KS) before and after the procedure was 73.3±6.3% and 83.9±4.9%, respectively. Conclusions. Interventions on ganglion impar are an effective method of treating patients with coccygodynia of various etiology, which significantly reduce pain according to the VAS scale (p&lt;0.001) and improve the quality of life according to the KS (p&lt;0.001) in dynamics after 1, 3, 6 months. Minimally invasive interventions on ganglion impar make it possible to reduce tissue trauma, to quickly recover for patients after the procedure, and to minimize any complications. In the first and second groups of the study, there was a decrease in the pain on the VAS from 8.0 cm to 2.0 cm (p&lt;0.0001) and from 7.0 cm to 2,7 cm (p&lt;0.001) before and after the procedure, respectively. In the first and second groups of the study, there was an improvement in the indicator of functional status according to the KS from 70% (95% сonfidence interval (CI) 60‒90%) to 90% (95% CI 70‒100%, p&lt;0.0001) and from 70% (95% CI 70‒90%) to 90% (95% CI 80‒100%, p=0.001) before and after the procedure, respectively.

THz radiation distribution for the identification of infiltrating ductal carcinoma in human breast model: a computational study

With numerous biomedical applications of terahertz (THz) imaging, spectroscopy, and sensing, the THz regime of the spectrum is quickly emerging as an important area of research with the potential to usher in a new era in the healthcare industry. In the medical field, THz radiation has been explored to diagnose and monitor several ailments, including foot diabetes, skin dryness, wounds, and burns. Compared to X-rays, THz waves' phase sensitivity to bodily fluid levels and water results in superior contrast and stronger absorption. This feature makes THz potentially useful for the diagnosis of various malignant tumor forms because cancerous tumors have higher water molecule contents than healthy tissues. The current study presents a computational analysis of a CW-THz point-by-point scanning technique for breast cancer detection. COMSOL multiphysics platform was utilized to create a multilayer three-dimensional breast model containing an irregular-shaped infiltrating ductal carcinoma in the glandular layer. The propagation of the THz radiation in the constructed breast model was simulated based on the radio frequency module and electromagnetic waves in the frequency domain interface. Furthermore, different volumes and locations of the induced tumor were examined. The results demonstrated significant disparities in the acquired electric distribution at different tumor sizes and sites between normal and diseased breasts. The resultant electric field for healthy breast ranged from 1.1 × 10–5 to 0.61 V/m, however, the electric field ranges following tumor addition fluctuate based on its volume and location. Additionally, the position of the THz source and detector array influences the reflected THz signal.

A Review on Material Selection Benchmarking in GeTe-Based RF Phase-Change Switches for Each Layer.

The global demand for radio frequency (RF) modules and components has grown exponentially in recent decades. RF switches are the essential unit in RF front-end and reconfigurable systems leading to the rapid development of novel and advanced switch technology. Germanium telluride (GeTe), as one of the Chalcogenide phase-change materials, has been applied as an RF switch due to its low insertion loss, high isolation, fast switching speed, and low power consumption in recent years. In this review, an in-depth exploration of GeTe film characterization is presented, followed by a comparison of the device structure of directly heated and indirectly heated RF phase-change switches (RFPCSs). Focusing on the prototypical structure of indirectly heated RFPCSs as the reference, the intrinsic properties of each material layer and the rationale behind the material selection is analyzed. Furthermore, the design size of each material layer of the device and its subsequent RF performance are summarized. Finally, we cast our gaze toward the promising future prospects of RFPCS technology.

Integrated frequency-modulated optical parametric oscillator.

Optical frequency combs have revolutionized precision measurement, time-keeping and molecular spectroscopy1-7. A substantial effort has developed around 'microcombs': integrating comb-generating technologies into compact photonic platforms5,7-9. Current approaches for generating these microcombs involve either the electro-optic10 or Kerr mechanisms11. Despite rapid progress, maintaining high efficiency and wide bandwidth remains challenging. Here we introduce a previously unknown class of microcomb-an integrated device that combines electro-optics and parametric amplification to yield a frequency-modulated optical parametric oscillator (FM-OPO). In contrast to the other solutions, it does not form pulses but maintains operational simplicity and highly efficient pump power use with an output resembling a frequency-modulated laser12. We outline the working principles of our device and demonstrate it by fabricating the complete optical system in thin-film lithium niobate. We measure pump-to-comb internal conversion efficiency exceeding 93% (34% out-coupled) over a nearly flat-top spectral distribution spanning about 200 modes (over 1 THz). Compared with an electro-optic comb, the cavity dispersion rather than loss determines the FM-OPO bandwidth, enabling broadband combs with a smaller radio-frequency modulation power. The FM-OPO microcomb offers robust operational dynamics, high efficiency and broad bandwidth, promising compact precision tools for metrology, spectroscopy, telecommunications, sensing and computing.

Use of the 433MHz band for underwater communications in controlled environments

This research aims to design and implement an underwater communication system using radio frequency modules and Arduino. Underwater wireless communication is challenging due to the attenuation of electromagnetic waves in water. However, radio frequency signals in the 433MHz range and the added antenna have shown successful data transfer. For this purpose, measurements are made at different distances, and data is collected in the aquatic environment and free space. A comparative analysis of the values of arrival powers and losses in the studied environment is carried out to verify the efficiency of this study in terms of range, transmission speed, and reliability.

Magnetron sputter deposition of boron carbide in Ne and Ar plasmas

Conventional magnetron sputter deposition of B4C uses Ar as the working gas. Here, we explore the magnetron sputter deposition of B4C with a Ne plasma, which is expected to exhibit larger sputtering yields than Ar. We study properties of films deposited with different substrate tilt angles with the magnetron source operated in either direct-current (DC) or radio-frequency (RF) mode in an Ar or Ne plasma. Results show that the B4C film properties are determined by a combination of sputtering ballistics and effects of the working gas on the plasma discharge and gas phase scattering of depositing species flux. At constant discharge power, deposition rates for Ar and Ne plasmas are similar, which is attributed to balancing effects of a higher ballistic sputtering yield of Ne and lower ion flux to the target. Both depositing B and C neutral species and bombarding ions have higher energies for the case of Ne plasmas. Films deposited with the RF-driven Ne plasma exhibit a uniform non-columnar structure, lowest oxygen impurity content, and highest mass density and mechanical properties at a cost of Ne incorporation and larger compressive residual stress.

A 55 μ W 2.4 GHz wake-up receiver with offset-based peak detection achieving −90dBm sensitivity for IoT applications

The paper proposes a 2.4 GHz ultra-low power wake-up receiver (WuRX) with offset-based peak detection and mixer-first based radio frequency (RF) front-end for IoT applications. The mixer-first based front-end eliminates RF modules to reduce power consumption. Based on the transparency of the passive mixing switches, a 2-path passive mixer (2-PPM) constructs the high-Q band-pass filter (BPF) at the RF port to improve out-of-band blocker rejection. The offset-based peak detection circuit adaptively extracts the reference voltage for the subsequent comparator according to the real-time signal amplitude of envelope detection, which eliminates the misjudgment of the comparator and improves the accuracy of demodulation. For low power consumption, a ring oscillator is used to generate the local oscillator (LO) signal and the frequency calibration scheme combined with coarse tuning and fine tuning is employed to improve the frequency stability, which completes 10-bit frequency tuning with 2 MHz resolution. Designed in TSMC 28 nm CMOS technology, the mixer-first based front-end achieves a conversion gain of 42 dB and a noise figure of 11.9 dB at 2.4 GHz, an S11 less than −15dB during 2.4–2.5 GHz. The frequency calibration scheme for the ring oscillator completes the 512 MHz dynamic range with a 2 MHz frequency tuning step. The WuRX can achieve −90dBm sensitivity with 55 μ W power consumption at 0.6 V supply voltage and the chip area of 0.19 mm × 0.24 mm.

IOT-Enabled Radio Frequency Home Automation System

The number one objective of this undertaking is to expand a present-day home automation device that leverages the abilities of the Internet of Things (IoT) and Radio Frequency (RF) technology. This device aims to deal with the evolving wishes of cutting-edge households through transitioning from manual switches to centralized, far flung-controlled systems. By integrating IoT-enabled gadgets which include smartphones, laptops, and drugs, the gadget gives improved comfort and manipulation over a extensive range, contingent upon the supply of a stable internet connection. Furthermore, this machine isn’t always most effectively beneficial for residential use but also affords sizable ability for business applications in business and medical settings. The integration of RF technology affords a simplified and effective solution for far off-managed home automation, catering to the elderly, disabled people, and facilitating green operations in numerous business environments. To obtain its functionality, the gadget is interfaced with a Wi-Fi module and an RF module, both linked to a microcontroller. This configuration permits the transmission of ON/OFF commands to a receiver, which in turn controls the connected masses. By running the faraway switch on the transmitter through an internet interface (thru the Wi-Fi module), users can remotely flip home equipment ON/OFF, harnessing the energy of wi-fi technology. This paper comprehensively explores the technological advancements and practical implications of these systems, as further elaborated in the ensuing segment.

A Super-Resonant Frequency Control for Handshaking of an Inductive Power Transfer System With Adjacent Units

In inductive power transfer (IPT) applications where multiple IPT units can appear closely, the wrong pairing of one transmitter (Tx) unit and receiver (Rx) unit can happen and may cause damages. For example, for automated guided vehicle and electric vehicle applications, one IPT charger may find multiple nearby Rx units through radio frequency modules. If the charger wrongly pairs with an Rx unit in an adjacent lane, the charger will attempt to charge the correct Rx unit using the information from the adjacent Rx unit, which is a faulty operation. In this letter, IPT coils are used to transmit handshaking information, which inherently avoids adjacent Tx/Rx units. During handshaking, only small ac currents would occur even with a high dc input. When the Tx and Rx are far away, system currents remain small. Hence, the approach is a safe solution to assist pairing. Experimental results have been provided for verification.