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Using Signals of Opportunity to Experience and Understand HF Ionospheric Radio Propagation

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2019 ASEE Annual Conference & Exposition


Tampa, Florida

Publication Date

June 15, 2019

Start Date

June 15, 2019

End Date

June 19, 2019

Conference Session

Engineering Physics and Physics Division Technical Session 1

Tagged Division

Engineering Physics and Physics

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Paper Authors


Paul Benjamin Crilly U.S. Coast Guard Academy

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Paul Crilly is a Professor of Electrical Engineering at the United States Coast Guard Academy. He received his Ph.D. from New Mexico State University, his M. S. and B.S. degrees at Rensselaer Polytechnic Institute, all in Electrical Engineering. He was previously an Associate Professor of Electrical and Computer Engineering at the University of Tennessee and was a Development Engineer at the Hewlett Packard Company. His areas of interest include laboratory development, antennas, wireless communications, signal processing, and instrumentation.

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This paper will investigate and observe the use of signals of opportunity to enable undergraduate engineering students to experience and thereby better understand how the E and F layers of the ionosphere can enable intercontinental reception of high frequency (HF) radio signals. Signals of opportunity could be NIST’s WWV at 2.5, 5, 10 and 15 MHz; Canada’s CHU at 3.33, 7.85 and 14.67 MHz as well as the BBC and other international short wave broadcast stations. Unless deflected, wireless distances are line of sight on the order of 50 km. Ground wave, tropospheric, and other effects make possible communication distances beyond line of sight. However, HF signals that deflect off the ionosphere can enable reliable communication distances in excess of 4000 km, and with multiple hops can span the entire globe. In addition to answering the question of the how and why of ionospheric or sky wave propagation, we will also discuss and show how students can directly experience the various limitations such as what occurs during day light hours when signals at the lower portions of the HF band are absorbed by the D layer and thus do not propagate much beyond line of sight, and how solar events such as sunspot cycles and solar eclipses affect ionospheric or sky wave communication. Building on this knowledge, students will better understand radio propagation and explain why everyday AM broadcast, and FM radio signals coverage is local only, but each exhibit different properties. Furthermore, students will better appreciate the necessity of frequency diversity to achieve more reliable wireless communication.

Crilly, P. B. (2019, June), Using Signals of Opportunity to Experience and Understand HF Ionospheric Radio Propagation Paper presented at 2019 ASEE Annual Conference & Exposition , Tampa, Florida. 10.18260/1-2--33517

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