@proceedings {931, title = {Analysis by Citizen Scientists of Doppler Radio Observations of the April, 2024 Solar Eclipse}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

The HamSCI community (Ham Radio Science Citizen Investigation) has analyzed high frequency radio observations of the total solar eclipse of April 8, 2024 and found interesting correlations. Nearly fifty ham radio operators recorded over 200 Doppler time series of the national time standard transmitters WWV in Colorado and CHU in Canada using specialized GRAPE (Great Radio Amateur Propagation Experiment) receivers. These observations are archived at the Personal Space Weather Station website, and cover ten frequencies from 0.6 to 25 MHz. There were over sixty different paths from transmitter to receiver at various angles across and along the path of totality from Texas to Maine. For each observation six citizen scientists collected demographic data, found distances and midpoints (where radio signals are reflected from the ionosphere), noted local eclipse information, measured the maximum Doppler shifts, counted multi-path signals, and judged the symmetry of the S-shaped Doppler curves over ingress and egress time periods. We found that the Doppler shifts depend mostly on the Sun{\textquoteright}s obscuration at the midpoint, but also on the carrier frequency and the distance between the transmitter and the receiver. At closer distances a radio wave measured a greater change in the path length as the bottom of the ionosphere retreated skyward and then returned as the Moon uncovered the Sun. \ 

}, author = {Mary Lou West and Nathaniel Frissell and Gary Mikitin and Gregory Popelas and Ronald Wilcox and McKenzie Denton and Robert Spalletta and William Engelke and Gwyn Griffiths and Steve Cerwin} } @proceedings {932, title = {Analysis of the HamSCI Solar Eclipse High Frequency Time Difference of Arrival Experiment Observations Using Automated Techniques}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

The objective of our research is to use narrowband linear audio pulses, which are sensitive to time displacement, and transmit them through High Frequency (HF) commercial off-the-shelf (COTS) single-sideband (SSB) amateur radios to measure changes in ionospheric reflection heights, specifically during a solar eclipse. This will be accomplished and automated using programming techniques learned in the Digital Signal Processing course at the University of Scranton, where the primary objective is to use TDOA (Time Difference of Arrival), a technique that measures the time displacement of single/multiple paths as they reach a receiving station. These TDOA values will be manipulated using a virtual height model that will yield different values of ionospheric layer heights based on the locations of the receiving and transmitting stations. During the October 2023 and April 2024 solar eclipses, WA5FRF transmitted a series of linear audio pulses (chirps) every 10{\textendash}15 minutes to various receiving stations on the 5, 7, and 14 MHz amateur radio bands. Received signals were squared and filtered to detect the waveform envelope. Correlation with a matched signal was then used to identify the start time of each chirp, after which a Fast Fourier Transform (FFT) was used to identify the beat-note frequency generated by multipath propagation. The October 2023 eclipse automated analysis shows that the F region reflection point was raised from 262.5 km at 17:00 UTC to 300 km at eclipse maximum at 17:30 UTC. The April 2024 eclipse analysis shows no real maximum reflection point; however, it does indicate an increase in layer height following maximum obscuration at 18:30 UTC. Both analyses are in good agreement with the hmf2 observations of the Austin Ionosonde. The intended purpose was to monitor multipath interference for 1{\textendash}2 hops off of the F2 layer; however, recent developments in this automated process yield additional data for other modes.

}, author = {Alexandros Papadopoulo and Gerard Piccini and Nathaniel Frissell and Steve Cerwin and Jesse McMahan and Paul Bilberry and Blackshear Samuel and Aidan Montaigne and Kristina Collins and Robert Spalletta} } @proceedings {751, title = {Toward Developing an Algorithm for Separation of Transmitters of High Frequency Chirp Signals of Opportunity for the Purpose of Ionospheric Sounding}, year = {2023}, month = {03/2023}, publisher = {HamSCI}, address = {Scranton, PA}, author = {Simal Sami and Nisha Yadav and Nathaniel A. Frissell and Robert Spalletta and Declan Mulhall and Dev Raj Joshi and Juha Vierinen} } @conference {643, title = {Evaluation of Techniques to Better Separate and Utilize Astronomical Radio Telescope Signals from those Due to Disturbances in the Ionosphere}, booktitle = {HamSC}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, organization = {HamSCI}, address = {Huntsville, AL}, abstract = {

Ionospheric disturbances impact radio signals that travel through them.\  These ionospheric scintillations are observed across the electromagnetic spectrum using a variety of methods.\  Previous studies have demonstrated that signals from radio telescopes can be used to measure and track these disturbances.\  Furthermore, a recent study suggests the separation of signals may be enhanced by concurrent measurements of ionospheric disturbances by multiple techniques and at different frequencies.\  This study discusses how astronomical and ionospheric signals from radio telescopes have been separated, how that separation might be improved by combining radio-telescope data with data from an alternate measurement methods and how ionospheric signals might be used to characterize ionospheric variability over both long- and short-term time scales.

}, author = {Robert Spalletta} }