Hari Vishnu

Research Fellow

Hari Vishnu

Hari Vishnu obtained his Ph.D degree in 2013 from the Nanyang Technological University (NTU), Singapore, in Computer Engineering. He did his B.Tech in Electronics and Electrical Engineering from National Institute of Technology, Calicut, in 2008.

He joined ARL in 2013. His current research interests at ARL are in machine learning for underwater applications, acoustic modelling, acoustic vector sensors and signal processing in impulsive noise. His Ph.D research involved the development of improved algorithms for underwater signal processing. These included detection & localization, acoustic vector sensor processing, developing robust methods in non-Gaussian noise, acoustic modelling and parameter estimation using Bayesian filtering.

Apart from research, Hari enjoys reading, listening to music and playing the flute. He is also passionate about anime, movies and TV series.

Email: hari (at) arl.nus.edu.sg

Research Interests



  1. V. N. Hari, B. Kalyan, M. Chitre and V. Ganesan, "Spatial modeling of deep-sea ferromanganese nodules with limited data using neural networks", IEEE Journal of Oceanic Engineering, 2017, DOI: 10.1109/JOE.2017.2752757
  2. A. Mahmood, M. Chitre, and V. Hari, "Locally-Optimal Inspired Detection in Snapping Shrimp Noise," IEEE Journal of Oceanic Engineering, 2017 (accepted).
  3. V. N. Hari and M. Chitre, “Robust estimation of modulation frequency in impulsive acoustic data,” IEEE Transactions on Aerospace and Electronic Systems, Aug 2017, DOI: 10.1109/TAES.2017.2677621 [http].
  4. V. N. Hari, G. V. Anand and A. B. Premkumar, “Narrowband signal detection techniques in shallow ocean by acoustic vector sensor array”, Digital Signal Processing, vol. 23 pp. 1645-1661, June 2013, [.pdf][http]©Elsevier
  5. V. N. Hari, A. B. Premkumar, and X. Zhong, “A Decoupled Approach for Near-Field Source Localization Using a Single Acoustic Vector Sensor”, Circuits, Systems, and Signal Processing, vol. 32, no. 2, pp. 843–859, Oct. 2012. [.pdf][http] ©Springer
  6. V. N. Hari, G. V. Anand, A. B. Premkumar, and A. S. Madhukumar, “Design and performance analysis of a signal detector based on suprathreshold stochastic resonance”, Signal Processing, vol. 92, no. 7, pp. 1745–1757, Jul. 2012. [.pdf][http] ©Elsevier.
Invited conference talks

  1. A. Mahmood, V. N. Hari and M. Chitre, "Model Based Signal Detection in Snapping Shrimp Noise", Underwater Communications and Network (UComms 2016), Lerici, Italy, September 2016 [.pdf]
  2. G. V. Anand, V. N. Hari and Z. Madadi, "Signal detection in non-Gaussian noise", SYMPOL 2011, Kochi, 2011


  1. V. Kalaiarasu, V. Hari, A. Mahmood and M. Chitre, "Predicting underwater acoustic network variability using machine learning techniques", IEEE Oceans 2017, Anchorage (Accepted)
  2. V. Hari , B. Kalyan and M. Chitre, "Spatial modeling and uncertainty characterization of polymetallic nodules in the Clarion-Clipperton zone", IEEE Oceans 2017, Anchorage (Accepted)
  3. A. Mahmood, M. Chitre and V. Hari, "Spatial Ambient Noise Inversion Using a Single Hydrophone", IEEE Oceans 2017, Anchorage (Accepted)
  4. B. Kalyan, V. Ganesan, M. Chitre and V. Hari, "Optimal Point Planning for Abundance Estimation of Polymetallic Nodules", IEEE Oceans 2017, Anchorage (Accepted)
  5. Wong Liang Jie, B. Kalyan, M. Chitre and V. N. Hari "Polymetallic Nodules Abundance Estimation using Sidescan Sonar: A Quantitative Approach using Artificial Neural Network", IEEE Oceans 2017, Aberdeen, Scotland, Jun 2017
  6. M. Hoffman-Kuhnt, Abel Ho, V. N. Hari, M. Chitre and E. Matrai , Alice Tse, "Buzz that Rod ! Acoustic Analysis and patterns of the echolocation signals of a blindfolded bottlenose dolphin performing a horizontal and vertical angular resolution task", Proceedings of 2015 Society for Marine Mammalogy Biennial Conference, San Francisco, Dec 13-18
  7. K. C. Unnikrishnan and V. N. Hari, "A vector sensing scheme for underwater acoustics based on particle velocity measurements", IEEE Oceans 2015, Washington DC, USA, Oct 2015
  8. X. Zhong, V. N. Hari, X. Shen, H. Wang, W. Wang, "Particle filtering for channel parameter tracking in a noisy shallow ocean environment using a vertical array", Asia-Pacific Conference on Synthetic Aperture Radar 2015, Singapore, Sep 2015
  9. V. N. Hari, M. Chitre, Y. M. Too and V. Pallayil, “Robust passive diver detection in shallow ocean”, IEEE Oceans 2015, Genova, Italy [.pdf]
  10. V. N. Hari, M. Chitre, "Robust signal processing in impulsive noise for Sonar", DSO Tech-know exhibition, Singapore, Jul 2014
  11. V. N. Hari, X. Zhong, A. B. Premkumar, "Near-field/far-field source localization in ocean with an acoustic vector sensor array using polynomial rooting", Proc. SYMPOL 2013, Kochi, India, Oct 2013 [.pdf] [http] ©IEEE 2013
  12. V. N. Hari, G. V. Anand, and A. B. Premkumar, “Narrowband detection in ocean with impulsive noise using an acoustic vector sensor array” , in 20th European Signal Processing Conference (EUSIPCO 2012), 2012, pp. 1334–1339. [.pdf] [http]
  13. X. Zhong, V. N. Hari and A. B. Premkumar, " An Optimal Importance Sampling based Particle Filtering for Channel Parameter Estimation in Shallow Ocean", Proc. IEEE Global Conference on Consumer Electronics 2012, Tokyo, Oct 2012.[http]
  14. V. N. Hari, G. V. Anand, A. B. Premkumar, and A. S. Madhukumar, “Underwater signal detection in partially known ocean using short acoustic vector sensor array”, in OCEANS 2011 IEEE - Spain, 2011, no. 65, pp. 1–9. [.pdf][http] ©IEEE 2011
  15. X. Zhong, V. N. Hari, A. B. Premkumar, and A. S. Madhukumar, “Particle filtering with enhanced likelihood model for underwater acoustic source DOA tracking”, in OCEANS 2011 IEEE - Spain, 2011, pp. 1–6. [http]
  16. V. N. Hari, G. V. Anand, and A. B. Premkumar, “Preprocessor based on suprathreshold stochastic resonance for improved bearing estimation in shallow ocean”, in OCEANS 2009, MTS, 2009, no. 65, pp. 1–8. [.pdf] [http]©IEEE 2009
  17. V. N. Hari, G.V. Anand , A. B. Premkumar, "Optimal suprathreshold stochastic resonance based nonlinear detector", Proc. 17th European Signal Processing conference (EUSIPCO 2009), Glasgow, 2009, pp. 2062 – 2066. [.pdf]


  1. V. N. Hari, "Improved techniques for detection and localization of underwater acoustic sources using acoustic vector sensors", Ph.D thesis, School of Computer Engineering, Nanyang Technological University, Singapore, 2013