Faculty Publications
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Item Introduction tо Microwave Photonics(SPIE, 2025) Raghuwanshi, S.K.; Singh, M.; Kumar, R.; Kumar, S.Microwave photonics is a rapidly growing field that lies at the intersection of microwave engineering and optics. The integration of photonics and microwave engineering has opened up new possibilities for high-speed communication, radar and sensing systems, and signal processing applications. This book contains both the basic theory and the experimental techniques to demonstrate the interdisciplinary applications of microwave photonic systems. It discusses the underlying concepts, techniques, and devices used in microwave photonics, as well as the latest advances in the photonic generation, processing, and distribution of arbitrary microwave waveforms. The role of fiber Bragg grating in microwave photonic systems is described from a dispersion compensation point of view. The book also provides a deeper understanding of microwave photonic sensor systems, highly steerable beamforming systems, and photonic excitation of antenna—the process of exciting the antenna using light or photons instead of electrical signals—with applications in aerospace, defense, telecommunication, and biomedical sensing. Overall, microwave photonics is an interdisciplinary field that deals with the interaction between light and microwaves. Its unique features, including high-speed, low-power consumption and large bandwidth, make it an attractive technology for future applications. This book is intended for researchers, engineers, and students who are interested in this exciting and rapidly evolving field. © 2025 Society of Photo-Optical Instrumentation Engineers (SPIE). All rights reserved.Item Fuzzy string matching algorithm for spam detection in twitter(Springer Verlag service@springer.de, 2019) Kumar, A.; Singh, M.; Pais, A.R.In recent times one of the most popular Internet activity around the world is visiting online social websites. The number of users and time spent by users on these social networks is increasing exponentially. Moreover, users tend to rely on the trustworthiness of data present on these networks. But in wrong hands this trustworthiness can easily be exploited and used to spread spams. Users can easily be harassed by spam messages which waste time and can fool users to click on malicious links. Spam effects many different type of electronic communications including instant messaging, email and social networks. But due to open nature, huge user base and reliance on users for data, social networks are worst hit because of spams. To detect spams from the social networks it is desirable to find new unsupervised techniques which can save the training cost which is required in supervised techniques. In this article we present an unsupervised, distributed and decentralized technique to detect and remove spams from social networks. We present a new technique which uses fuzzy based method to detect spams, which can detect spams even from a single message stream. To handle huge data in networks, we implement our technique to work on MapReduce platform. © Springer Nature Singapore Pte Ltd. 2019.Item A New Kaiser-Bessel Constant Modulus Technique for Smart Antenna Beamforming(Springer Science and Business Media Deutschland GmbH, 2022) Shashidhara, K.S.; Dakulagi, V.; Kaur, J.; Yeap, K.H.; Singh, M.; Ratnesh, R.K.In this work, an improved constant modulus algorithm (CMA) blind beamformer exploiting the Kaiser-Bessel window which is dubbed as ‘KB-CMA’ for the smart antenna system is presented. In array signal processing, especially in beamforming technology, the CMA is one of the most popular methods due to its low complexity. However, this beamformer has a very slow convergence time and has a large side lobe level (SLL). This hinders the utility of the CMA method in dynamic circumstances where the speedy capture of the user signal is required. Also, this method is not suitable in the wireless applications where conditions of the channel are speedily varying. To circumvent this problem and to make the classical CMA suitable for practical applications, we propose an improved CMA. The major advantage of the new method is that its time of convergence is almost several times quicker than the classical CMA. Furthermore, we exploit the Kaiser-Bessel window to suppress the SLLs of the improved CMA. Experimental results demonstrate that the proposed method has fast convergence time and the reduced SLL. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item A Study on Depth Estimation from Single Image Using Neural Networks(Institute of Electrical and Electronics Engineers Inc., 2022) Shree, R.; Madagaonkar, S.B.; Singh, M.; Chandra, M.T.A.; Rathnamma, M.V.; Venkataramana, V.; Chandrasekaran, K.Depth estimation is fundamental in upcoming technology advancements like scene understanding, robot vision, intelligent driver assistance systems, and many new technologies. Estimating the depth of objects from a viewport can be achieved using various mathematical, geometrical, and stereo concepts, but the process is unaffordable and erroneous. Depth estimation from a single can be accurately done using neural networks. Although this is a challenging task, researchers around the globe have published various works. The works include different neural network standards like CNN, GANs, Encoder-Decoder. The paper analyses and examines famous works in this field of study. Later in the paper, a comparative survey of depth estimation approaches using neural networks is done. © 2022 IEEE.Item Numerical investigation of Microwave Photonic Link Using Different Electrical Filters(Institute of Electrical and Electronics Engineers Inc., 2023) Drishti, D.; Thayaba Nausheen, A.; Singh, M.In optical fiber communication systems, the performance is affected by a critical parameter called dispersion. Dispersion causes a pulse of light to broaden as it travels through a medium. This is because the different wavelengths or modes in the pulse travel at slightly different speeds, causing them to arrive at different times. Over a long distance, this can cause the pulse to spread out and overlap with neighboring pulses, leading to errors in data transmission or other types of signal degradation. To overcome this problem, there is a demand for efficient filters (both optical and electrical) in the dispersion compensating modules. In this work, we have analyzed the performance of two Electrical Filters (Low pass Butterworth and Raised Cosine filters). The Opti-system software is used for numerical modeling, which confirm that Raised Cosine Filter is better than Butterworth electric filters. The maximum Q-factor of 16.0572 and a minimum bit rate of 2.48771e-058 at 10 Gbit/s is obtained near the telecommunication wavelength. © 2023 IEEE.Item Simulation of Radio over Fiber System for Microwave Signal Generation using Sub- Carrier Modulation Technique(Institute of Electrical and Electronics Engineers Inc., 2023) Singh, V.; Meena, K.S.R.; Singh, M.Nowadays, Radio over fiber (RoF) technology is used in a variety of applications, including wireless communication systems, satellite communication systems, and radar systems. In this paper, we reported a sub-carrier modulation with Amplitude Shift Keying (SCM-ASK) system which supports the transmission of various signals across a single-mode fibre with enhanced encryption efficiency. The quality of the received signal is usually poor in RoF systems, a number of factors may contribute to this problem, such as high bit error rates (BER), low Q-factor values, and the receiver may not be working in a high data rate network. To overcome this, the Q-factor needs to be raised while BER should be brought down to assured values. Using Opti-System software, SCM-ASK is investigated at various channel spacings and fibre lengths. Also, the RoF system performance is analyzed in terms of BER, Q-factor, and the eye diagram patterns. © 2023 IEEE.Item Performance Improvement of Single-Loop Optoelectronic oscillator using Er-Yb codoped fiber Amplifier(Institute of Electrical and Electronics Engineers Inc., 2023) Renuka, B.; Meena, M.; Singh, M.This paper reports a low phase noise single-loop optoelectronic oscillator (OEO) using Er-Yb codoped fiber amplifier (EYDFA). Its performance is compared with Erbium-Doped Fiber Amplifier (EDFA) in terms of the Quality factor (Q), phase noise, and eye diagrams. The opti-system simulation confirms 36.14 Q-factor and -149.08 dBc/Hz phase noise at 10 kHz offset frequency with Er-Yb codoped fiber amplifier. Also, the reliability study is performed using different fiber loop lengths to determine the optimized OEO design. The proposed OEO generates a 10 GHz microwave signal with low-frequency drift along a 5 km optical fiber loop, which is suitable for X-band radar applications. © 2023 IEEE.Item Comparative Study of Millimeter-Wave-Over-Fiber Transmission Link with Different Photodiodes(Institute of Electrical and Electronics Engineers Inc., 2024) Singh, A.; Mishra, S.K.; Dinesh Achalaram, C.; Singh, M.In optical fiber communication, there is an expo- nential growth in data traffic demand. Hence, there is a need for advanced and efficient signal generation methods that offer a wider frequency range, higher tunability, and lower distortion. These optical fiber networks have long-distance capabilities and high data rates essential for intercontinental connections. This paper investigates the performance comparison of PIN photodetector and avalanche photodetector (APD) in optical fiber communication in terms of quality (Q) factor and eye patterns. The simulation model, utilizing microwave photonics (MWP) technology, implemented in OptiSystem software incorporates a Mach-Zehnder modulator (MZM) for optical signal modulation and a Bessel filter for spectral shaping. Photodetectors are susceptible to noise, which may occur due to thermal noise, shot noise, or dark current, and generate signals with increased bit error rate (BER) and degraded signal quality. To overcome these problems, photodetectors with suitable materials and designs are utilized to improve responsivity and reduce noise levels. A maximum Q factor of 7.6019 and minimum bit error rate of 1.4075 × 10-14 at 10 Gbps over a 25 km single-mode optical fiber network is obtained in the mm-wave wavelength range. Theoretical analysis of the suggested system is also discussed. © 2024 IEEE.Item Optimization of indium tin oxide-based all-optical switch using finite element method(American Institute of Physics, 2024) Sahu, S.K.; Khanna, A.; Vankalkunti, S.; Singh, M.The rapid development of optical communication systems necessitates the advancement of efficient and versatile all-optical switches. In this study, we propose an indium tin oxide (ITO)-based all-optical switch that harnesses the unique properties of this transparent conducting oxide material. The working principle of the proposed switch relies on the optical Kerr effect, where the refractive index of ITO changes by the influence of incident light. By exploiting the non-linear response of ITO to intense light pulses, we demonstrate its feasibility as a primary component in all-optical switching applications. With ITOs electric tunable ENZ effect, our proposed switch achieves an extinction ratio (ER) of 9.2 dB, insertion loss (IL) of 4.3 dB, and figure of merit (FoM) of 2.14. Our findings reveal that the ITO-based switch exhibits ultrafast response times and low energy consumption, making it suitable for high-speed optical networks. © 2024 Author(s).Item MIMO based radio-over-fiber link for millimeter wave generation using external optical modulator(American Institute of Physics, 2024) Meena, K.S.R.; Rao, A.; Singh, M.In this paper, photonically assisted millimeter wave signal generation techniques are proposed for modern space applications. For this, two designs are investigated with different optical modulators, namely, amplitude modulator and Dual Drive-Mach Zehnder Modulator (DD-MZM). A 2*2 Wavelength Division Multiplexing (WDM) transmitter with a 100 GHz frequency spacing is used to broadcast Multiple-Input Multiple-Output (MIMO) signals, and it encodes the signals using a 1Gbps pseudo-random bit sequence with return-to-zero coding. The Electrical Constellation Visualizer is used to examine the distortion in the proposed Radio over Fiber (RoF) links. The opti-system software simulation for DD-MZM design confirms a high-frequency millimeter wave signal with 60 dBm optical sideband suppression ratio (OSSR) and radio-frequency spurious suppression ratio (RFSSR) 72 dBm. Whereas Amplitude Modulator based architecture produces mm-wave signals with high Q-factor and low loss. Therefore, the merging of MIMO and RoF technology is a better solution for generating mm-wave signals for next-generation communication systems. © 2024 Author(s).