@proceedings {1045,
	title = {Personal Space Weather Station Observations of the Gannon Geomagnetic Storm},
	year = {2026},
	month = {03/2026},
	publisher = {HamSCI},
	address = {Newington, CT},
	abstract = {The geomagnetic storm known as the Gannon Storm took place from 10-13 May 2024. Classified as a G5 geomagnetic storm, the Gannon Storm was the most extreme event of its kind to occur in the past two decades. Space weather events of this magnitude have significant impacts on orbiting satellites, navigation systems, power grids, and communications. Particularly, geomagnetic storms are known to disrupt technologies that utilize the high frequency (HF) portion of the radio spectrum. The aim of this study is to understand the Gannon Storm{\textquoteright}s effects on HF propagation. Using the Ham Radio Science Citizen Investigation{\textquoteright}s network of personal space weather stations (PSWSs), Doppler shift data gathered during the Gannon Storm is examined and compared against data collected on days with quieter geomagnetic conditions. PSWS receivers detected elevated Doppler shifts among traveling HF signals and more interruptions to the signals than is typical. Studying the Gannon Storm{\textquoteright}s effects on HF propagation can inform how technologies that rely on these frequencies may be better equipped against similar extreme space weather events in the future.~~~},
	author = {Rebecca Potter and Nathaniel Frissell and Gwyn Griffiths and Kuldeep Pandey}
}
@proceedings {1044,
	title = {A Python data analysis and synthesis toolbox for PSWS Doppler data:  A time-of flight case study},
	year = {2026},
	month = {03/2026},
	publisher = {HamSCI},
	address = {Newington, CT},
	abstract = {A prototype Python toolbox is available to aid HamSCI Personal Space Weather Station (PSWS) data interpretation1. The toolbox currently has two themes. First, a set of frequency- (FFT) and time-domain (autocorrelation) scripts for estimating and plotting Doppler frequency, Doppler spread and signal level of PSWS digital_RF data. For bimodal spectra an experimental script estimates Doppler of two peaks, assigns to propagation modes and tries to track even if they cross. Second, a set of scripts invoking PyLap 2D and 3D ray tracing to obtain synthetic spectrograms of one- and two-hop E and F region, low and high ray, propagation modes. Time series of take-off angle, reflection apogee and time of flight (ToF) are derived from automated PyLap simulations. Novel ToF measurements between WWV and KD7EFG, Utah, provide an interpretation challenge case study. Apogee height simulation time series show expected propagation modes, importantly showing periods with two co-propagating modes, and, by omission, suggesting when sporadic E (Es) was present. 5 MHz Es propagation, with minimal vertical height variability, and ToF of 2.12 ms, provided the benchmark to show consistent ToF measurements within 60 us. The more dynamic F region gave rise to commensurate variations in ToF. However, ToF estimates became scattered with two co-propagating modes from WWV (e.g. 5 MHz E and F). 15 MHz Es propagation showed consistent ToF of 2.19 ms from a weak signal 50 dB below one-hop F2. Fascinatingly, an interval with ToF of 14 ms reducing to 8 ms from a weak but strengthening signal was attributed, with certainty, to two-hop sidescatter using 3D PyLap simulation. One-hop via F region only occurred briefly, with correct ToF of 2.81 ms. As the 15 MHz path from WWVH opened, with a strong signal seen in Doppler shift, ToF measurements on the path from WWV, of weak two hop sidescatter, became very scattered. This case study shows the importance of being able to use PSWS Doppler analysis to interpret new ToF measurements.  In conclusion, these results herald a significant advance in the HamSCI Community{\textquoteright}s ability to characterize ionospheric propagation channels. },
	author = {Gwyn Griffiths and Scott Newell and Paul Elliott and Clint Turner and Brett Anderson and Michael Hauan and Rob Robinett}
}
@proceedings {938,
	title = {Post-sunset sporadic F propagation: A sign of electron density isopleth convergence?},
	year = {2025},
	month = {03/2025},
	publisher = {HamSCI},
	address = {Newark, NJ},
	abstract = {<p>Reception of WSPR spots enables alerts of propagation anomalies such as the outlier Doppler shifts on 14 MHz seen across North America during a post-sunset Travelling Ionospheric Disturbance on 26 July 2024. For an hour this event opened one-hop paths and added two-hop propagation to already-open one-hop paths. For analysis and interpretation I used the multiband milliHertz precision Doppler measurements of WWV at HamSCI RX888 station N8GA as it showed one- and two-hop signals. Two-hop propagation began 4 minutes after an inflexion on the fall-from-peak of one-hop Doppler. The prior rise from 0.5 Hz to 0.8 Hz took 8 minutes. After the inflexion the fall back to 0.5 Hz took 22 minutes, with a distorted flat top. If Doppler shift was solely attributable to advection, reflecting region vertical motion, crest to trough height reduction was ~69 km. However, it is not clear how electron density isopleth advection could increase electron density, hence critical frequency, to allow two-hop propagation. If part of the Doppler arose from the plausible, but less often considered, convergence of electron density isopleths a reasonable hypothesis is that electron density could, temporarily, be sufficiently enhanced to support two-hop propagation. To try and identify the two Doppler sources I examined the LF and HF skirts of the two-hop Doppler spectrum immediately on the appearance of great circle propagation with its narrow spectral peak. The skirts, 13 dB to 25 dB below the peak, were from forward-scattered paths. I modeled Doppler shift on forward-scattered paths using 3D PyLap ray tracing and assumed pseudo-reciprocity. On these longer than great circle paths Doppler shift was less for the same reflection height change. This simple model suggests that Doppler on forward-scattered paths explained the LF skirt but not the HF skirt. Rather than simply attributing the HF skirt to convergence I consider other methods to test the assumption of advection only. Future studies may need to explicitly test whether attributing the Doppler shift purely to advection is warranted.\&nbsp;</p>
},
	author = {Gwyn Griffiths}
}
@conference {400,
	title = {Patterns in Received Noise: Methods, Observations and Questions (ePoster)},
	booktitle = {HamSCI Workshop 2020},
	year = {2020},
	month = {03/2020},
	publisher = {HamSCI},
	organization = {HamSCI},
	address = {Scranton, PA},
	abstract = {<p>There are valid concerns that local noise, often as common mode, is an increasing problem for radio amateurs. By adding two noise measurement algorithms to a robust Weak Signal Propagation Reporter (WSPR) processing and reporting package\&nbsp;-\&nbsp;wsprdaemon\&nbsp;-\&nbsp;we now have the capability to record and share noise level measurements from over twenty amateur stations. With locations from Maui to Moscow, and ranging from very quiet rural Northern California, Utah, and Austria to more typical suburban noise environments we have observed a multitude of patterns in received noise on the LF to HF bands (136 kHz to 28 MHz). These patterns show clearly where and when the local noise floor becomes a limiting factor. More intriguingly, we have observed coherent fluctuations in the noise over periods of hours at a pair stations 1000 km apart. Now with observations from a {\textquoteright}diamond{\textquoteright} of four stations we can look in more detail at the timing of these coherent fluctuations. With over six months of observations every two minutes from several stations we can show systematic seasonal variations in the daily noise patterns. We think we understand the root causes of some of the features, such as the local noon minimum and the post-sunset maximum in late spring and summer. However, we have yet to reach a satisfactory understanding for some patterns, including a transition to a daytime noise maximum in autumn. The challenging task of calibration to a field strength in free space will not be ignored, but for this presentation it will be set aside as we concentrate on patterns and not absolute noise levels. This presentation will outline the noise measurement methods, show examples of noise patterns from several stations, introduce the on-line database and its Grafana interface that delegates will be able to explore, and we will seek comments, insights and suggestions as to causes for the patterns and next steps for this collaborative effort.</p>
},
	author = {Gwyn Griffiths and Rob Robinett and Glenn Elmore and Clint Turner and Tom Bunch and Dennis Benischek}
}
