volume | PIER Journals

Abstract

The main objective of the current work is to develop a Very Low Frequency (VLF) monitoring system for characterizing low layer ionosphere. Low layer ionosphere is important for communication, and some researchers stressed that lower layer ionosphere can be a precursor to earthquake event. The VLF monitoring system composed of a 1-m antenna, a preamplifier to amplify the signal, an ADC converter and a data acquisition system. The optimization of 1-m antenna received dual frequencies 19.2 kHz and 19.8 kHz from South Vijayanarayanam, India and North West Cape, Australia, respectively. Subsequently, a low pass filter was designed in the preamplifier to pass VLF signals from 0-30 kHz. The results revealed that the system was able to characterize diurnal variation: sunrise and sunset and detect changes in the lower layer ionosphere region due to Solar activity.

1. Indira Devi, M., I. Khan, and D. N. Madhusudhana Rao, "A study of VLF wave propagation characteristics in the earth-ionosphere waveguide," Earth Planet and Space, Vol. 60, 737-741, Jul. 2008.
doi:10.1186/BF03352822 Google Scholar

2. Contreira, D. B., F. S. Rodrigues, K. Makita, et al. "An experiment to study solar flare effects on radio-communication signals," Advances in Space Research, Vol. 36, 2455-2459, Mar. 2004.
doi:10.1016/j.asr.2004.03.019 Google Scholar

3. Abd Rashid, M. M., M. Ismail, A. M. Hasbie, and R. Nordin, "Ionospheric disturbances triggered by solar flare events during solar maximum - May 2013," 2015 IEEE 12th Malaysia International Conference on Communications (MICC), Malaysia, 2015. Google Scholar

4. Kumar, A. and S. Kumar, "Space weather effects on the low latitude D-region ionosphere during solar minimum," Earth, Planets and Space, 66-76, 2014. Google Scholar

5. "The Earth's Ionosphere,", [Online], Available: http://solar-center.stanford.edu/SID/acti-vities/ionosphere.html, Accessed: Nov. 28, 2017. Google Scholar

6. Cohen, M. B., U. S. Inan, and E. W. Paschal, "Sensitive broadband ELF/VLF radio reception with the AWESOME instrument," IEEE Transaction on Geoscience and Remote Sensing, 1-15, 2009. Google Scholar

7. Harriman, S. K., W. Paschal, and U. S. Inan, "Magnetic sensor design for femtotesla low-frequency signals," IEEE Transaction on Geoscience and Remote Sensing, Vol. 48, 396-402, 2010.
doi:10.1109/TGRS.2009.2027694 Google Scholar

8. Tan, L. M., "Development of TNU-SuperSID teaching module for observing the effects of solar activities on the lower ionosphere," Journal of Physical Science and Application, Vol. 5, 116-122, 2015. Google Scholar

9. Holt, C. A., "Basic amplifier configuration," Electronic Circuits Digital and Analog, 383-389, John Wiley & Sons, Canada, 1978. Google Scholar

10. Samanes, J. E., J. P. Raulin, and E. L. Macotela, "Estimating the VLF modal interference distance using The South America VLF network (SAVNET)," Radio Science, Vol. 50, 122-129, Feb. 2015.
doi:10.1002/2014RS005582 Google Scholar

11. Muraoka, Y., "A new approach to mode conversion effects observed in a mid-latitude VLF transmission," Journal of Atmospheric and Terrestrial Physics, Vol. 44, 855-862, Oct. 1982.
doi:10.1016/0021-9169(82)90038-1 Google Scholar

Dr. Nur Ain Zakaria

Dr. Afifah Taat

Dr. Siti Amalina Enche Abdul Rahim

Dr. Wan Zul Adli Wan Mokhtar

Dr. Mohamad Huzaimy Bin Jusoh