@article {667, title = {Amateur Radio: An Integral Tool for Atmospheric, Ionospheric, and Space Physics Research and Operations}, journal = {White Paper Submitted to the National Academy of Sciences Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033}, year = {2022}, author = {Nathaniel A. Frissell and Laura Brandt and Stephen A. Cerwin and Kristina V. Collins and David Kazdan and John Gibbons and William D. Engelke and Rachel M. Frissell and Robert B. Gerzoff and Stephen R. Kaeppler and Vincent Ledvina and William Liles and Michael Lombardi and Elizabeth MacDonald and Francesca Di Mare and Ethan S. Miller and Gareth W. Perry and Jonathan D. Rizzo and Diego F. Sanchez and H. Lawrence Serra and H. Ward Silver and David R. Themens and Mary Lou West} } @article {670, title = {Fostering Collaborations with the Amateur Radio Community}, journal = {White Paper Submitted to the National Academy of Sciences Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033}, year = {2022}, author = {Nathaniel A. Frissell and Laura Brandt and Stephen A. Cerwin and Kristina V. Collins and Timothy J. Duffy and David Kazdan and John Gibbons and William D. Engelke and Rachel M. Frissell and Robert B. Gerzoff and Stephen R. Kaeppler and Vincent Ledvina and William Liles and Elizabeth MacDonald and Gareth W. Perry and Jonathan D. Rizzo and Diego F. Sanchez and H. Lawrence Serra and H. Ward Silver and Tamitha Mulligan Skov and Mary Lou West} } @proceedings {620, title = {On the Use of High Frequency Surface Wave Oceanographic Research Radars as Bistatic Single Frequency Oblique Ionospheric Sounders}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

We present an investigation demonstrating that passively collected high frequency coastal oceanographic radars, with suitable waveform characteristics, can be used as single frequency oblique ionospheric sounders. To our knowledge, this is one of the first demonstrations of dual purpose use of these HF coastal radars, in addition to their primary role as ocean current monitors.\ We present a technique for extracting the virtual height using the E-region as a time calibration; this technique is agnostic of the software defined radio used.\ The application of this investigation may be useful for expanding spatial coverage for traveling ionospheric disturbance studies, day-to-day variability studies, or within data-assimilation routines.\ Additionally, HF coastal radars may be used by the scientific community or radio amateur as an another suitable RF source. We performed an experiment in which we collected 10 days of data in March 2016 from a site in Maryland, USA (MSR) and 21 days of data collected in October 2020 from a site near Clemson, South Carolina, USA (CARL). For both experiments, we used a similar hardware setup utilizing an Ettus USRP N210 software defined radio, including the GPSDO unit.\ We performed radar signal processing to obtain the group delay time from the passively received signal of Coastal Ocean Dynamics Applications Radar (CODARs).\ Our observations for both intervals focused on one frequency band at 4.53718 MHz which included three CODAR transmitters located on the Coast of North Carolina and Virigina with callsigns: DUCK, CORE, and LISL. The digisonde located at Wallops Island, VA (WP937) was used as the diagnostic to compare and validate with the observations collected from oblique CODAR-MSR(CARL) paths.

}, author = {Stephen R. Kaeppler and Ethan Miller} } @proceedings {462, title = {Toward interpretation of HF propagation data obtained by the HamSCI Community - Ray Tracers and Ionospheric Models}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, address = {Scranton, PA (Virtual)}, abstract = {

Perhaps one of the most pressing questions the Ham Sci community needs to address is how data obtained by the tangerineSDR or other platforms will be interpreted to obtain scientifically useful information.\  One approach is to produce an appropriate forward model describing the ionosphere and use ray tracers to convert that model into observables that are measured using SDRs.\  The purpose of this talk is to discuss these issues in general terms, but also to discuss simulation strategies that could be useful for the data collected by a network of radio amateurs.\  I will also present on the development of an open source python-based 3-D Jones Stephenson Ray tracer and other developments out of my laboratory that are relevant to ray tracing, including implementation using cuda and the development of point-to-point ray tracing.

}, author = {Stephen R. Kaeppler and Scott Driggers and Andrew Wetzel and Alexander Murtha and Tedi Godfrey} } @conference {325, title = {Sounding the Ionosphere with Signals of Opportunity in the High-Frequency (HF) Band}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, publisher = {HamSCI}, organization = {HamSCI}, address = {Cleveland, OH}, abstract = {

The explosion of commercial off-the-shelf (COTS) education- and consumer-grade hardware supporting software-defined radio (SDR) over the past two decades has revolutionized many aspects of radio science, bringing the cost and calibration of traditionally complex receiver hardware within the grasp of even advanced amateur experimenters. Transmission has now become the limiter of access in many cases, particularly through spectrum management and licensing considerations. Fortunately, several classes of signals endemic to the HF band lend themselves to processing for ionospheric characteristics: time and frequency standard broadcasters, surface-wave oceanographic radars, amateur radio transmissions, and ionospheric sounders.

This presentation is a tour of these signals of opportunity and techniques for collecting and processing them into ionospheric characteristics, with emphasis on distributed receivers collecting on a small number (four or fewer) of coherent channels. Receiving techniques will be discussed for near-vertical ({\textquotedblleft}quasi-vertical{\textquotedblright}) incidence skywave (NVIS or QVI), long-distance oblique soundings, and transionospheric sounding. Soundings will be demonstrated from space-based, ground-based, and maritime platforms.

Binary, Doppler, delay, cone angle of arrival, and polarization observations will be exploited, depending on the signal type and capability of the collector. Each of these techniques conveys different, but not always {\textquotedblleft}orthogonal,{\textquotedblright} information about the ionospheric skywave channel. The information content of each datum will be discussed with respect to the implications for inverting the local or regional ionosphere from the observations. More importantly than inverting the full ionosphere, some of these techniques are sensitive indicators of ionospheric irregularities, structures, and instabilities, that might otherwise be difficult to study due to limited geographic coverage with larger, more exquisite instrumentation.

}, author = {Ethan S. Miller and Gary S. Bust and Gareth W. Perry and Stephen R. Kaeppler and Juha Vierinen and Nathaniel A. Frissell and A. A. Knuth and Philip J. Erickson and Romina Nikoukar and Alexander T. Chartier and P. Santos and C. Brum and J. T. Fentzke and T. R. Hanley and Andrew J. Gerrard} }