Defence Electronics Application Laboratory

This paper presents a wideband digital predistorter designed for frame-based frequency-hopped Long-Term Evolution (LTE) signals to mitigate nonlinearities in the high-efficiency operating region of power amplifiers. In frequency-hopping systems, the frequency-dependent nonlinear behaviour of the power amplifier becomes even more critical, necessitating a practical linearization approach. Given the constraints on implementation within dwell time and the limited resources of Field Programmable Gate Arrays (FPGAs), a single wideband predistorter is preferable over multiple frequency-dependent narrowband predistorters. It is crucial to select an appropriate training signal for modelling the wideband predistorter, as it depends on the training signal’s Complementary Cumulative Distribution Function (CCDF). Since the CCDF of a multitone signal varies with the initial phase of its tones, three different multitone configurations with distinct initial phases are used to model the power amplifier’s nonlinearities. After training, the resulting model is applied to predistort the frequency-hopped LTE signal. The in-band and out-of-band performance of the predistorted LTE signals is analysed for all three types of multitone training signals. Results indicate that the training signal with a CCDF most similar to the LTE signal achieved the best Normalized Mean Square Error (NMSE), which is critical for reliable link establishment. The ZC-706 and ADRV 9371 evaluation board was used as the experimental setup for proof of concept. The best NMSE obtained is -31.5408dB, with 21 hop frequencies.

Climatic parameters and vegetation indices are significantly influenced by anthropogenic activities, posing concerns for climate prediction amid global warming. This study examines atmospheric dynamics and the distribution of climatic and anthropogenic factors across varying altitudes using satellite remote sensing data for the year 2023. Findings indicate that experimental sites are affected by anthropogenic activities like ozone (O₃) and biomass carbon stocks (BCS), while sulfur dioxide (SO₂) and sulfate (SO₄) exhibit maximum variability, particularly in the Himalayan foothills. Higher altitudes show long-term temperature increases, with land surface temperature (LST) and precipitation (PPT) fluctuating alongside normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). All locations exhibit a non-platy kurtic distribution of climatic and anthropogenic indicators, with a positively skewed relationship between skewness and kurtosis. These findings highlight the potential of climatic parameters and vegetation indices for microclimate analysis and weather forecasting models. The study also emphasizes the utility of multivariate statistical approaches in assessing climate variations at temporal and spatial scales using remote sensing data.

<bold>Introduction:</bold> Spirometry is essential for evaluating lung function, with Forced Vital Capacity (FVC) and Forced Expiratory Volume in the first second (FEV1) being key indicators. Current reference equations for these parameters are based on age, gender, height, and ethnicity, but fail to account for altitude’s effect on lung function. However, Individuals living at high altitude often show improved respiratory function due to long term physiological adaptations, which is not included in existing reference equations. This study evaluates spirometric values at high altitude (>2,500 meters) and low-altitude plains, assessing the need for altitude-based adjustments. <bold>Materials and Methods:</bold> A total of 1,000 participants (250 healthy individuals and 250 COPD patients each from high and low altitude) were recruited. Spirometry was performed following standard protocols, measuring FVC and FEV1. Predicted values of FVC and FEV1 were analyzed to identify significant differences between high and low-altitude groups (p < 0.05). <bold>Results:</bold> Residents of high altitude showed higher spirometric values. Healthy individuals at high altitude had mean FVC and FEV1 values of 95.3% ± 5.2 and 92.8% ± 4.9, compared to 88.1% ± 5.7 and 85.6% ± 5.3 for low-altitude counterparts (p < 0.001). COPD patients showed similar trends, with higher FVC and FEV1 at high altitude (68.2% ± 6.1 and 60.4% ± 5.8) versus low altitude (61.7% ± 5.9 and 55.1% ± 5.6; p < 0.001). <bold>Conclusion:</bold> Altitude significantly impacts lung function, suggesting the need for altitude adjusted spirometric equations to improve diagnostic accuracy and management, particularly for COPD patients. Further studies are needed to refine these equations for varying elevations.

More than 60 percent of World population will use Internet and among these users’ 90 percent users will have their detailed profiles in any one of the social media, 321 million new users came in last 6 months. Social media are interactive computer-mediated technologies that facilitate the creation and sharing of information and expression via virtual networks. Cyber-crime is computer-oriented crime which involves computer and network. In this paper I am focusing about how crime rate will expand by social media in other words how social media users will become victims of cyber-crime and measures to be taken by the users along with avoidance of crime.Aim•To recognize about the temperament of social media in Cyber Crime•Steps to be taken to evade crime rate by social media

The paper discusses design, simulation, development and evaluation of right hand circularly polarized (RHCP) microstrip antenna with wide axial ratio bandwidth using single coaxial feed for SATCOM applications. The antenna consists of a lower and upper rectangular patch separated by 10 mm air gap in stacked configuration, fabricated on 62 mil RT Duroid 5880 dielectric material. Length and width of the patch as well as a cross structure, orthogonally placed two slots, in lower patch have been optimized to obtain wideband circular polarization. Stacked configuration of microstrip antenna with optimized air gap has been utilized for wide impedance bandwidth. Measured antenna has gain of 8.58 dBic and beamwidth more than 60 degrees at 2.69 GHz. The antenna shows wide impedance bandwidth of about 20 percent and wide axial ratio bandwidth greater than 8 percent. The experimental results of the antenna are quite close to the simulated one in terms of axial ratio bandwidth and impedance bandwidth. The novelty of this microstrip antenna is wide 3 dB axial ratio bandwidth, between 2.54 GHz to 2.77 GHz, using single coaxial feed for SATCOM applications.

This paper represents a compact, transparent microwave energy harvesting (MEH) system at a 3.3 GHz frequency band to assist the rechargeable battery system of the smart watch. The operating frequency of the proposed system is targeted to the 5G and beyond communication’s frequency bands. It is feasible to integrate a CPW-fed transparent folded monopole circular patch antenna onto the dial of the smart watch. Transparent conductive materials ITO and PET as substrates are utilized to design the proposed antenna to enhance the transparent efficiency of the rectenna system. The radiated gain of the proposed antenna is achieved of 2.16 dB at 3.3 GHz, with an omnidirectional radiating field pattern. Further, a microwave energy harvesting system is designed that consists of an antenna, a matching circuit, and a voltage doubler rectifier circuit by utilizing the Schottky diode (HSMS2860). The maximum output voltage of the rectenna system is obtained at 0.926 volts, while the maximum output power of 0.5484 (mW) is achieved at 3.3 GHz. The maximum RF-dc conversion efficiency (PCE%) of the proposed microwave energy harvesting system is obtained at 55%.

Landslide susceptibility mapping plays an imperative role in mitigating hazards and determining the future direction of developmental activities in mountainous regions. Here, we used 518 landslide occurrences and nine landslide-conditioning parameters to build landslide vulnerability models in the Kailash Sacred Landscape (KSL), India. Four multivariate statistical models were applied, namely the generalized linear model (GLM), maximum entropy (MaxEnt), Mahalanobis D2 (MD), and support vector machine (SVM), to calibrate and compare four maps of landslide susceptibility. The results demonstrated the outperformance of Mahalanobis D2 for predictability compared to other models obtained from the area under the receiver operating characteristic curve (ROC). The ensemble model data shows that 10.5% of the landscape has susceptible conditions for future landslides, whereas 89.50% of the landscape falls under the safe zone. The occurrence of landslides in the KSL is linked to the middle elevations, vicinity to water bodies, and the motorable roads. Furthermore, the observed patterns and the resulting models exhibit the major variables that cause landslides and their respective significance. The current modelling approach could provide baseline data at the regional scale to improve the developmental planning in the KSL.