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ORIGINAL RESEARCH article

Front. Astron. Space Sci.

Sec. Space Physics

This article is part of the Research TopicHeliophysics Big Year: Education and Public Outreach ReportsView all 18 articles

HamSCI HF Multipath Propagation Mode Analysis Using Amateur Radios and Audio Waveforms Sensitive to Time Difference of Arrival

Provisionally accepted
Steve CerwinSteve Cerwin1Jesse Thomas McMahanJesse Thomas McMahan1Alexandros Sophocles PapadopoulosAlexandros Sophocles Papadopoulos1,2Gerard N. PicciniGerard N. Piccini1,2Nathaniel Anthony FrissellNathaniel Anthony Frissell1,2*Kristina V. CollinsKristina V. Collins1,3Aidan MontareAidan Montare1Paul BilberryPaul Bilberry1Samuel BlackshearSamuel Blackshear1David R. ThemensDavid R. Themens1,4
  • 1Ham Radio Science Citizen Investigation (HamSCI), Scranton, PA, United States
  • 2University of Scranton, Scranton, United States
  • 3Space Science Institute, Boulder, United States
  • 4University of Birmingham, Birmingham, United Kingdom

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This study describes a method to deduce the ionization layer virtual height and propagation path geometry responsible for communication between two HF radio stations a fixed distance apart. The method measures the Time Difference of Arrival (TDOA) between mul-tipath propagation modes involving the active ionospheric layers and reconciles the data with a virtual height model of the ionosphere. The TDOA approach was implemented by transmitting audio signals that are sensitive to a time delay when summed together as happens in a receiver during multipath reception. The TDOA method eliminates the need for any absolute time references or extensive equipment calibration that would be required for an absolute time of flight (TOF) measurement. The audio waveforms used by the method included 1-cycle audio bursts, linear audio chirps of controlled sweep rate, and pseudorandom noise (PN) bursts.

Keywords: Amateur radio, citizen science, HAM radio, HamSCI, Heliophysics, Ionosphere, multipath TDoA, Space weather

Received: 12 Oct 2025; Accepted: 09 Jan 2026.

Copyright: © 2026 Cerwin, McMahan, Sophocles Papadopoulos, Piccini, Frissell, Collins, Montare, Bilberry, Blackshear and Themens. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Nathaniel Anthony Frissell

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

Supplementary Material