@proceedings {931, title = {Analysis by Citizen Scientists of Doppler Radio Observations of the April, 2024 Solar Eclipseations}, 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 {939, title = {Distributional Characteristics of Short-Term 2022 20-Meter Sequential Matched WSPRDaemon Noise Observations}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

Understanding the characteristics and structure of one{\textquoteright}s data is critical for effective data analysis. Currently, WSPRDaemon data are being used in background noise level, HF propagation, Doppler shift, and correlational studies. Here we use Exploratory Data Analysis (EDA) on short-term (2-minute), sequential observations of WSPRDaemon observations to gain insights into the distributional characteristics of the data prior to more advanced modeling or analytical procedures. Our findings uncovered data outliers and puzzling distributional characteristics. \ While consistent in their presence, these anomalies were unique from one receiving station to the next. These findings warrant further consideration and explanation before researchers invest time attempting more complex analytic procedures. \ They also strongly suggest that a parallel data base of meta-data for the receiving stations would be extremely helpful for future studies.\ 

}, author = {Robert Gerzoff and Gwyn Griffiths} } @proceedings {926, title = {Interim Findings of the HamSCI DASI2 HF Antenna Project}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

An ad hoc HamSCI DASI2 Antenna Group was tasked in late 2024 with evaluation of antenna options for the DASI2 grant. We present the the materials, methods, and criteria we have so far developed to accomplish this along with preliminary results. \ Antenna systems under consideration include DXE-RSEAV-1FVI, N6GN SAS, LZ1AQ loop dipole, and others. \ The materials include key elements already intended for use in the grant -- the RX888-SDR and software such as the KA9Q-Radio system, the KA9Q-Web spectrum display, WSPRDAEMON, and spot and noise reception reports to wspr.net, wsprdaemon.org, and pskreporter. \ The methods leverage ITU noise figures, known broadcast station locations, significant recent improvements in the spectrum display, and analysis of the local site. \ The criteria so far include antenna performance metrics, site evaluation, ease of deployment, support needs, and cost. This effort will enable us to provide good quality information, some of which we present, for selecting an appropriate antenna for the grant. \ However, the effort to solve this particular task has also demonstrated the general utility of these tools and methods for the amateur radio community. \ A view of the entire HF spectrum enable at-a-glance assessments that can help one more effectively identify and solve problems and optimize reception given the natural limitations of one{\textquoteright}s site. \ One can see recognizable patterns suggesting local and propagated noise, overmodulation, aliasing, inadequate front-end gain, ground loops, and more. \ One can compare two (or more) antennas or one antenna with itself at different sites or orientations, the effects of feed-line placement, interactions with nearby structures or foliage, and more. \ These efforts will inform the choice of an antenna to use for the DASI2 grant but can prove immediately useful for all hams and scientists in understanding and optimizing their receiving systems.

}, author = {Michael Hauan and Glenn Elmore and Rob Robinett and Gwyn Griffiths and Dve Witten and Ulli Grunow and Clint Turner} } @proceedings {951, title = {Monitoring tropospheric propagation at 24 GHz: A pilot study}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

HamSCI{\textquoteright}s upper atmosphere and space physics focus has drawn on ionospheric observations by hams using protocols including WSPR, and precision measurements of transmitters WWV and CHU with the information gathered into databases. Such techniques are applicable to other amateur radio fields to advance understanding of propagation. As an example, we describe a UK pilot system for monitoring tropospheric propagation at 24 GHz. The transmitter (JO01mt22 12 m ASL) on 24.048945 GHz has a GPS disciplined oscillator and outputs 7 W ERP to an omnidirectional antenna. Transmissions alternate each minute between WSJT-X{\textquoteright}s JT4G sub-mode and a carrier with CW identification. The 53 km test path over the Thames Estuary glances the sea surface to a receiver (JO01qj81 80 m ASL). At the receiver a masthead down-converter to 400 MHz IF connects to a Raspberry Pi controlled SDR running OpenWebRX. The pilot SDR, an RTL-dongle, is to be replaced by an Airspy R2. The data monitoring software, based on early WsprDaemon, processes WSJT-X wav files. It logs basic data of callsign, SNR and frequency from JT4G and signal and noise levels from carrier-only intervals. SNR derived from the carrier shows greater resolution and dynamic range than from JT4G. Measurements of frequency with lower scatter are obtained from cross-correlating the JT4G signal with its sync vector, finding the peaks via continuous wavelet transform then interpolation.\  Data on environment variables that may affect propagation is collected from a lightship, including air and sea temperature, relative and absolute humidity and wave height. Rain rate is from a shore station near the transmitter. Radio and environmental data go to a database with a Grafana dashboard for visualisation. Encouraging semi-quantitative effects of changes in the environment on propagation have been observed. These include: signal dropout at absolute humidity above 8 g/m3; increased variance of frequency with waveheights above 1 m; and signal level reducing gradually by 8 dB during the passage of a cold front with a band of rain up to 1 mm/hour.

}, author = {Gwyn Griffiths and John Worsnop} } @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 = {

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.\ 

}, author = {Gwyn Griffiths} } @proceedings {955, title = {Sunrise: A natural perturbation enables identification of propagation modes from distinct Doppler shifts}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, author = {Gwyn Griffiths} } @proceedings {826, title = {Analysis of changes to propagation and refraction height on specific paths induced by the 14 October 2023 eclipse}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

Signal and noise levels, alongside precise frequency and frequency spread measurements were collected by over 20 WsprDaemon stations prior to, during, and after the October 2023 eclipse using FST4W digital mode. By combining fortuitous home locations with eclipse-specific portable operations, augmented with multiband transmitters at selected sites, the group has gathered a rich data set over 3.5 MHz to 28 MHz. Path geometry includes along- and across-eclipse, from 10s km to over 5000 km. Different geometries, path lengths and frequencies have enabled quantitative analysis of eclipse-induced propagation changes. Reduced D region absorption resulted in 7-9 dB increase in propagated-in noise on 7 MHz at KPH/KFS. The triangular form of the noise anomaly contrasted with a flat-topped +13-15 dB signal level anomaly on 3.57 MHz on a 466 km path. Reduced F2 layer critical frequency (foF2) resulted in several phenomena on 14 MHz identified via frequency spread changes. Two-hop propagation reverted to one-hop on an 1808 km path. On a 1055 km path one-hop changed to an above-the-basic MUF mode - two-hop sidescatter - with signal levels 30 dB lower. Reduced foF2 affected two-hop along-eclipse paths of 4400 km to 5000 km from Costa Rica to Nevada and California on 28 MHz. At ca. 4400 km signals were lost twice, as the second hop, then the first, were affected, with recovery between. Signals at 5000 km were not completely lost. Simple ray-trace modelling to match the observations suggested effective sunspot number (SSNe) had dropped from 125 to ~70. As stations were GPS-disciplined or GPS-aided precise Doppler shift measurements at two-minute intervals with 0.1 Hz resolution were obtained. On a 545 km path Doppler shift at 3.57 MHz, 7 MHz and 10.14 MHz were converted to path velocities and, integrated back and forward in time from a single F2 layer height from the Pt. Arguello ionosonde, gave a credible diurnal profile of refraction height. Compared to 15th October the 14th showed a triangular-shaped height anomaly with a maximum of +33 km. These and other results illustrate the effectiveness of path-specific analysis of FST4W data for eclipse studies.

}, author = {Gwyn Griffiths} } @proceedings {868, title = {Ray-trace modelling of diurnal variation in two-hop sidescatter propagation}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

Two-hop sidescatter, an off-great circle propagation mode enabling above-the-basic-MUF communications, is identified by low SNR and high spectral spread (width between -3 dB points). Observable at 7 MHz and above, as a daytime mode it enables propagation from 10s km to 100s km. Additionally, it may appear before, and or after, great-circle one-hop propagation as it operates with a lower F2 layer critical frequency. We have devised a computationally efficient modelling approach for two-hop sidescatter using 3D ray tracing. First, ray landing spots from a transmitter are found over 360{\textdegree}\ azimuth and a sensible range of elevations. Second, the process is repeated for a transmitter at the receiver. The key assumption is that reciprocity holds sufficiently to avoid the computationally demanding need to place a transmitter at every transmitter ray landing spot. A scattering metric, the product of the number of landing spots from transmitter and pseudo-transmitter in a 1{\textdegree}x1{\textdegree}\ area, is a useful approximation to the location and strength of the sidescatter. The off-great circle scattering location from the model has been verified by a rotating-antenna experiment at 14 MHz on paths from Northern California to Utah and Oregon using FST4W digital mode. The diurnal variations of sidescatter location and strength are particularly interesting for a meridional transmitter and receiver geometry: morning (local time) scatter from the east, from land on the California to Oregon path, with afternoon through nighttime scatter from the west, from the ocean. We discuss a qualitative comparison of hourly model simulations with signal level and circuit reliability data from FST4W spots. The nighttime minimum in both parameters is pronounced in the observations and model. An afternoon dip in circuit reliability, without reduction in signal level, is tentatively explained by the model showing strongest scatter alternating between east and west before settling to the west. We postulate that severe multipath scatter from both east and west, land and ocean, sufficiently increased frequency spread to reduce probability of decode for the ~6 Hz bandwidth FST4W mode. This study illustrates the usefulness of combining 3D ray tracing with purposeful observations to explain an underappreciated propagation mode.

}, author = {Gwyn Griffiths and Devin Diehl and R. Lynn Rhymes and Frederick Wahl} } @proceedings {850, title = {Trial of applying PHaRLAP raytracing to reproduce Ham spot data}, year = {2024}, month = {03/2024}, publisher = {HamSCI}, address = {Cleveland, OH}, abstract = {

HamSCI is one of the NASA{\textquoteright}s official citizen science projects. HamSCI\ spots database, which is from Reverse Beacon Network (RBN) and Weak Signal Propagation Reporter Network (WSPRNet), is of interest. Information of date, time, frequency, latitude, and longitude of transmitter and receiver are used. PHaRLAP is a raytracing tool that can trace the HF radio wave in 2D and 3D. We use the IRI model to generate the required ionospheric information. We employ the PHaRLAP\ to reproduce the ham spots database by launching the HF radio wave from the transmitter, of which its location is obtained from the HamSCI\ spots database. Then, we trace the O-mode propagation of the wave. The wave arrival latitude and longitude are then mapped into a grid based on the Amateur Radio Maidenhead Grid. Finally, we compare the raytracing-based arrival grid with the HamSCI\ arrival grid. The results, under the assumption of 1-hop propagation, show that the PHaRLAP\ raytracing can reproduce the HamSCI\ spots database well.

}, author = {Kornyanat Hozumi and Nathaniel A. Frissell and Min-Yang Chou and Gwyn Griffiths and William D. Engelke and Jia Yue and Shing Fung and Masha Kuznetsova} } @proceedings {748, title = {How Do I Talk From Scranton to Pakistan Using​ High Frequency Amateur Radio?​}, year = {2023}, month = {03/2023}, publisher = {HamSCI}, address = {Scranton, PA}, abstract = {

This poster will demonstrate the possible ways to send propagation transmissions from The University of Scranton to Karachi, Pakistan. To do this, VOACAP will be used to map out possible paths and peak times for transmission and then WSRP.rocks will be used to compare the empirical VOACAP model outputs to observed data. A recommendation will then be made for the optimal time and frequency to communicate using high frequency (HF) radio between Scranton, PA and Karachi, Pakistan.

}, author = {Zainab Shah and Gwyn Griffiths and Rob Robinett and Nathaniel Frissell} } @proceedings {697, title = {Identifying 14 MHz Propagation Modes Using FST4W SNR and Spectral Spread}, year = {2023}, month = {03/2023}, publisher = {HamSCI}, address = {Scranton, PA}, abstract = {

The FST4W protocol within the WSJT-X family of weak signal communications programs has an advantage over the widely used WSPR protocol in that it estimates spectral spreading. With modern equipment of modest cost, readily available to the radio amateur, spectral spread at the transmitter and receiver can be less than 30 mHz. This is much lower than spectral spread imposed on signals by ionospheric refraction or ground or sea scatter. Simple two-dimensional scatter plots of spectral spread and signal to noise ratio, alongside time series plots, show clear clustering attributable to different propagation modes. Using a single FST4W transmitter in Northern California and reports from eleven receivers from 2.4 km to over 3000 km to the west, north and east spectral spreading/signal to noise ratio clusters for surface wave and ionospheric 1F and 2F paths were easily identifiable. Other clusters were not so obvious. In particular, the prevalence of 2F ground side-scatter, or skew off great circle propagation, also termed {\textquoteright}above the basic maximum usable frequency{\textquoteright} propagation, at ranges of 40 to 1000 km was unexpected. This mode was also seen after dusk at more distant receivers, following on from 1F propagation as the maximum usable frequency fell. This mode was easily tracked across different receivers by its high spectral spread, 500 mHz to 650 mHz, some eight times that of 1F propagation. Instances of {\textquoteright}above the basic maximum usable frequency{\textquoteright} nighttime propagation due to, we hypothesize, refraction from patches in the ionosphere with much higher electron density than the background plasma were identified by their low spectral spreading at 1000 km and 1525 km. Identifying the particular propagation mode over a path may be of interest to the radio amateur, for example, if the current mode is 2F ground side-scatter, antenna headings along the great circle path may not give best results. Propagation mode identification using FST4W could be a radio amateur contribution to the ionospheric science programs of the 2023 and 2024 Festivals of Eclipse Science, charting changes in propagation modes as changes in solar flux affected ionospheric dynamics and structure.

}, author = {Gwyn Griffiths} } @proceedings {606, title = {Contrasting effects of the 3-5 November 2021 geomagnetic storm on reception in Colorado of WSPR transmissions from North-Eastern North America with those from Australia}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

Solar wind particles from three M-class flares hit the Earth{\textquoteright}s magnetic field around 19:30 UTC on 3 November 2021. The planetary geomagnetic disturbance index (Kp) peaked at 7 that evening and the following morning. At the USGS Boulder Geomagnetic Observatory, Colorado the vertical magnetic field anomaly was below -40 nT between 07:38 UTC and 12:56 UTC on 4 November, dipping briefly to -75 nT. These dramatic space weather events are examined using WSPR spots at N6GN, near Fort Collins, Colorado. Between 10:30 UTC and 11:00 UTC the 7 MHz WSPR spot count showed a ~90\% drop compared with previous days at that time interval. Second, the median distance for remaining spots increased to 7089 km from ~2500 km of previous days. Furthermore, the noise level dropped about 4 dB. At that time of day the noise at N6GN{\textquoteright}s remote receiver is limited by propagated-in noise rather than local or receiver noise. Central to the observed spot count decrease and median distance increase was a 98\% reduction in spots received from grid FN, North Eastern North America: down to 5 spots from a typical 245 on other days in the same interval. But what caused that precipitous drop? We look at signal levels of individual transmissions to try and understand whether received signal levels dropped below the noise or whether Doppler flutter spread the signals beyond the bandwidth of the WSPR decoder. We also seek to understand the increase in spots from Australia compared with previous days. During the storm itself, signal levels from Australia were unchanged; it was not until the following day that levels and the number of spots decreased. We caution and investigate that the very narrow band transmissions may not be decoded more due to spectral distortion and spreading rather than the more usual lack of signal to noise ratio. This analysis provides a valuable use case for WSPR transmissions, reporting via wsprnet.org, augmented with noise estimates and on-line access via the WsprDaemon database with quick-look Grafana and animated Octave visualizations.

}, author = {Gwyn Griffiths and Glenn Elmore} } @proceedings {473, title = {Visualising propagation to mid-latitudes from a shipboard WSPR transmitter on a passage from 27oN to 70oS using the WsprDaemon database, and how to access the data}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, address = {Scranton, PA (Virtual)}, abstract = {

WSPR transmitters and or receivers on polar research ships provide opportunities for several interesting propagation studies. Such studies include propagation across the Boreal and Austral Auroral Ovals with the ship working in the Polar Regions, or, as in this case, on mid-latitude propagation with the ship on transit. For RV Polarstern{\textquoteright}s voyage from Gran Canaria (27.5oN) to Neumayer III station, Antarctica (70.5oS) from 27 December 2020 {\textendash} 18 January 2021 a WSPR transmitter (DP0POL) operated on all bands 160{\textendash}10 meters. Heatmaps of the number of spots received in Europe and North America each hour, each day, and on each band have been generated from the WSPR data held on the WsprDaemon server. These spot-count heatmaps, proxies for circuit reliability, clearly delineate the diurnal variation in band opening times and how those diurnal variations vary systematically over a 100o span of latitude on the voyage south. However, quantitative assessment of the spot numbers needs care; the number of reporters receiving spots changes with time and distance. Furthermore, there were far fewer distinct reporters for the MF and upper HF bands (11 for 160 m and 14 for 10 m compared with 447 for 40 m and 473 for 20 m). The heatmaps of SNR show several intriguing features, including steps from no decodes to SNRs some 10 dB above the WSPR decoding threshold as bands open and close. A Grafana dashboard is available for all to explore at http://logs1.wsprdaemon.org:3000/d/QGlNSz-Gk_2\  Other ways to obtain WSPR data from the WsprDaemon database are outlined, including using Octave, KNIME, R, Python, PySpark and Clickhouse. A worked example shows how to use Octave to generate a time sequence of great circle maps, as a movie, of where WSPR spots from DP0POL were received on the voyage from 27.5oN to 70.5oS.

}, url = {https://hamsci2021-uscranton.ipostersessions.com/?s=57-BC-D3-11-D9-50-97-40-0D-F8-D2-C5-AA-73-79-6A}, author = {Gwyn Griffiths and Rob Robinett} } @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 = {

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\ -\ wsprdaemon\ -\ 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.

}, author = {Gwyn Griffiths and Rob Robinett and Glenn Elmore and Clint Turner and Tom Bunch and Dennis Benischek} }