@proceedings {1040, title = {Introduction to Baseband Processing}, year = {2026}, month = {03/2026}, publisher = {HamSCI}, address = {Newington, CT}, abstract = {

Today, much RF digital signal processing is done at baseband, defined here as a signal with frequencies centered around DC or 0 Hz. Baseband processing is somewhat analogous to using an intermediate frequency (IF), as done in a superheterodyne receiver with typical IF frequencies of 455 kHz (AM) or 10.7 MHz (FM), but where the IF is at 0 Hz and where the resulting baseband signal contains both positive and negative frequencies. Just as intermediate frequencies of superheterodyne receivers gave advantages in analog receivers, baseband processing gives certain advantages in digital receivers. Furthermore, most modern Software Defined Radios output in-phase / quadrature (IQ) data streams, containing both amplitude and phase information and centered at baseband. This includes the IQ output of the popular {\textquotedblleft}ka9q-radio{\textquotedblright} software environment used in HamSCI development of the Personal Space Weather Station system. A good understanding of baseband processing and its typical applications is thus useful. In this tutorial, we will introduce a common definition of baseband processing and explore its uses. The presentation will include a reminder of Fourier / frequency domain and complex signal representations. We will discuss the advantages of processing of IQ signals at baseband and will give examples of their use in common tasks. These include signal demodulation and filtering, including asymmetric filtering around 0 Hz. A brief discussion on creating a baseband signal from a non-baseband signal and converting a baseband signal to a non-baseband signal will also be presented. Interactive demonstrations will be provided as well for active learning, easy modification, and experimentation.

}, author = {Bill Liles and Philip Erickson and Ethan Miller} } @proceedings {1022, title = {A Low-Cost Low-Power Chirp Ionosonde for Studying the Ionospheric Impacts of Space Weather}, year = {2026}, month = {03/2026}, publisher = {HamSCI}, address = {Newington, CT}, abstract = {The ionosphere is a region of the atmosphere characterized by both ions and electrons. It is highly active and experiences changes in parameters such as electron density at different altitudes, based on the energy absorbed from the sun. Ionosondes are a type of radar used to gather data about the height of the ionosphere by transmitting a signal towards the ionosphere. This signal is refracted back to the Earth{\textquoteright}s surface and received in such a manner that return echoes can be timed to calculate the height profile of the bottomside ionosphere. Traditional ionosondes require large antenna systems and high amounts of power. Recent advancements in software defined radio (SDR) technology, advanced digital signal processing, and computational efficiency enable the size, cost, and power demands of an ionosonde system to be reduced. An Ettus N200 Universal Radio Peripheral was used in our system to verify the reliability of our methods, and during the 2024 total solar eclipse, the system was successfully used to sound the ionosphere. It recorded virtual layer height data comparable to multimillion-dollar ionosonde systems. Since then, we have updated the system to use the newer Red Pitaya SDRlab 122-16. This more affordable board is able to sound the ionosphere, using the same methods as the Ettus based system. Additionally, the system is now in a smaller and more portable form. Currently, we are improving its ability to collect data automatically and be controlled remotely. Furthermore, we are continuing to improve our sounding methods to obtain more data using the same hardware.}, author = {Gerard Piccini and Andrew Rodland and Robert McGwier and Robert Spalletta and Nathaniel Frissell and Majid Mokhtari and Philip Erickson} } @proceedings {949, title = {Climatology of Large-Scale Traveling Ionospheric Disturbances Observed with 14 MHz Amateur Radio Using a Novel Automated Detection Technique}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

We present a multi-year climatology of Large Scale Traveling Ionospheric Disturbance (LSTID) period oscillations observed using 14 MHz amateur (ham) radio data. Traveling ionospheric disturbances (TIDs) are quasi periodic electron density perturbations in the F region ionosphere that affect radio communications and can help with understanding energy transport throughout the coupled magnetosphere-ionosphere-neutral atmosphere system. These are seen, in daytime, as variations in contact ranges in 14 MHz amateur radio communication reports recorded by automated monitoring systems such as the Weak Signal Propagation Reporting Network (WSPRNet), the Reverse Beacon Network (RBN), and PSKReporter. A new deterministic and fully automated method was developed for identifying and quantifying these disturbances. This technique, which filters for TID wave periods between 1 and 5 hours and curve fits a sinusoidal function to the first hop skip-distance edge of observed communication ranges, provides both TID amplitudes and periods. In this study, we present full year climatologies of LSTID events over the continental United States (CONUS) using RBN, WSPRNet, and PSK observations from 2016- 2021. Results are organized as a function wave period, amplitude, and season. We find that LSTIDs increase in winter and decline during the fall and spring, with slight enhancements in the summer and occasional brief declines in LSTID winter activity. This seasonal pattern shows consistency with previous studies and observations of LSTIDs and medium scale TIDs that suggests this behavior may be associated with neutral wind filtering in the middle atmosphere, sudden stratospheric warming (SSW) events, and multi-step vertical coupling (MSVC) processes. MSVC is a process where gravity waves (GWs) from the lower neutral atmosphere propagate upwards, break, and produce new, higher-order GWs in the thermosphere and TIDs in the ionosphere.

}, author = {Diego Sanchez and Nathaniel Frissell and Mary Lou West and V. Lynn Harvey and Sharon Vadas and Erich Becker and Gareth Perry and William Engelke and Nicholas Callahan and Philip Erickson} } @proceedings {961, title = {A Low-Cost Low-Power Chirp Ionosonde for Studying Eclipse Ionospheric Impacts}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

The ionosphere is a region of the atmosphere characterized by both ions and electrons. It is highly active and experiences changes in parameters such as electron density at different altitudes, based on the energy absorbed from the sun. Ionosondes are a type of radar used to gather data about the height of the ionosphere by transmitting a signal towards the ionosphere.\  This signal is refracted back to the Earth{\textquoteright}s surface and received in such a manner that return echoes can be timed to calculate the height profile of the bottomside ionosphere. Traditional ionosondes require large antenna systems and high amounts of power. Recent advancements in software defined radio (SDR) technology, advanced digital signal processing (DSP), and computational efficiency enable the size, cost, and power demands of an ionosonde system to be reduced. Two systems are currently used in this project: the Ettus N200 Universal Radio Peripheral (USRP) and the newer Red Pitaya SDRlab 122-16. Using amateur radio fan dipoles and GNU Radio code, the Ettus system was used successfully to sound the ionosphere during the 2024 total solar eclipse. It recorded virtual layer height data comparable to multimillion-dollar ionosonde systems. We are now working to assemble the Red Pitaya system into a smaller form that can be assembled inexpensively and operated with ease. In the following weeks we will improve our sounding methods to be able to obtain more data.

}, author = {Gerard Piccini and Robert McGwier and Robert Spaletta and Nathaniel Frissell and Majid Mokhtari and Philip Erickson} }