@proceedings {1057, title = {The DASI2 HamSCI Whistler Catcher VLF Reception System}, year = {2026}, month = {03/2026}, publisher = {HamSCI}, address = {Newington, CT}, abstract = {

The Whistler Catcher VLF Reception System is a very low frequency software defined radio (VLF SDR) system. It utilizes an open hardware, open software, and open data design and philosophy to facilitate and promote citizen science in the study of VLF phenomena; including the Earth{\textquoteright}s natural radio emissions, VLF amateur radio transmissions in the 8270 Hz and 5710 Hz bands, and lightning stroke location. The system consists of both hardware and software. The hardware consists of VLF Active Antenna along with a VLF interface box to supply power and interface the signal; a GNSS interface box to provide a pulse per second (PPS) signal for the purposes of frequency calibration and timestamping; a Behringer UMC202HD USB audio interface for data acquisition, and a thin client PC with serial port. The designs of the VLF Active Antenna, VLF Interface Box, and GNSS Interface Box are all open hardware. The software includes vlfrx-tools, an open source software toolkit primarily for the application of VLF signal capturing, calibration, timestamping, filtering, storage, live listening, retrieval, visualization, EbNaut amateur mode decoding, and other signal processing functions in over 30 individual program utilities. It was written by Paul Nicholson G8LMD [SK], a passionate VLF enthusiast to whom the Whistler Catcher VLF Reception System is dedicated.

}, author = {Jonathan Rizzo and Nathaniel Frissell} } @proceedings {948, title = {The Whistler Catcher Thin: An Advanced VLF Reception System Based on the Whistler Catcher Pi}, year = {2025}, month = {03/2025}, publisher = {HamSCI}, address = {Newark, NJ}, abstract = {

The Whistler Catcher Pi is a VLF Reception System that captures the VLF spectrum up to 48 kHz using a VLF Active Antenna, Audio Injector Stereo soundcard, GNSS receiver, and a Raspberry Pi running vlfrx-tools software. The system has the ability to capture science-grade VLF data using common off the shelf components. It can timestamp with GNSS accuracy, remove mains hum, automatically capture natural radio events like dawn chorus and whistlers, automatically record amplitude and absolute phase of Navy VLF transmitters to detect SIDs and GRBs, calculate the Time of Group Arrival of sferics, record EbNaut transmissions from VLF amateurs, and many more. It was installed in December 2021 and is still in continuous operation, having captured over 100 whistlers, detected hundreds of SIDs, and an EbNaut transmission at 8.270 kHz from DL3JMM in Germany. Having built on this success, we propose the Whistler Catcher Thin, a VLF reception system that can capture spectrum up to 96 kHz utilizing the same VLF Active Antenna, Behringer UMC202HD USB Audio Interface, and Dell Wyze 5070 Thin Client. The added processing power and higher sample rate from these low cost components lend well to a low cost network of these VLF reception systems for DASI2, adding observations to simultaneous HF and magnetometer observations. With a network of at least six systems, the HamSCI lightning location network can be realized.

}, author = {Jonathan Rizzo} } @proceedings {723, title = {Three-channel VLF Data Acquisition and Signal Processing with a Raspberry Pi, Multi-channel soundcard, and GPS Receiver}, year = {2023}, month = {03/2023}, publisher = {HamSCI}, address = {Scranton, PA}, abstract = {

Using a Raspberry Pi, Audio Injector Octo multi-channel soundcard, and GPS receiver, a 3-channel VLF data acquisition system can be realized with an E-field receiver and orthogonal loop H-field receiver for triple axis reception of VLF natural phenomena and Amateur VLF transmission. Signal timestamping for correlation is accomplished with the GPS receiver and signal processing is accomplished with vlfrx-tools software. A network of these systems with associated VLF receivers has applications such as lightning location and location of other natural radio signals, sferic analysis, natural radio event study in multiple locations, interferometry of Amateur VLF transmissions, and more.

}, author = {Jonathan Rizzo} } @proceedings {718, title = {W2NAF-KC3EEY VLF Observatory - A Year of Operation}, year = {2023}, month = {03/2023}, publisher = {HamSCI}, address = {Scranton, PA}, abstract = {

After a year of operation, the W2NAF-KC3EEY VLF Observatory has detected thousands of sferics and tweeks, over fourty whistler events, two major dawn chorus events, two SAQ transmissions, and the first ever Amateur VLF transmissions from Radio Ameteur DL3JMM at 8270.03Hz using the EbNaut digital mode. This demonstrates that a simple VLF receiver with powerful signal processing from vlfrx-tools software using a Raspberry Pi, soundcard, and GPS receiver can serve both the VLF professional and amateur community. Using this, it{\textquoteright}s possible to construct a network of VLF receivers and perform signal processing from multiple locations for applications such as lightning location and location of other natural radio signals, sferic analysis, natural radio event study in multiple locations, interferometry of Amateur VLF transmissions, and more.

}, author = {Jonathan Rizzo} } @proceedings {627, title = {Installation and Operation of the KC3EEY/W2NAF VLF Reception System}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

A VLF Reception System was installed at the W2NAF KC3EEY VLF Observatory located in Springbrook, PA. The VLF preamp/antenna is based on the s1-1 design by Paul Nicholson, author of vlfrx-tools, which is encased in a PVC pipe. The signal is recorded using an Audio Injector Stereo soundcard and Raspberry Pi with vlfrx-tools recording and monitoring the signal. The system has a wide variety of science and amateur uses. A confirmed QSO of SAQ was made on Christmas Eve. QSOs from the Dreamers Band below 9 kHz were also confirmed using weak signal detection and EbNaut decoding. Possible effects from the January 15th, 2022 Tonga underwater volcano eruption were also observed along with VLF/ELF data from outside sources will be presented.

}, author = {Jonathan Rizzo and Nathaniel A. Frissell} } @proceedings {626, title = {VLF LEAF Module for the Tangerine SDR HamSCI Workshop 2022 Progress Update}, year = {2022}, month = {03/2022}, publisher = {HamSCI}, address = {Huntsville, AL}, abstract = {

Development of the VLF LEAF Module continues despite the global electronic component shortage. Since the Tangerine SDR cannot be built currently due to long lead times of the Intel Max 10 FPGA, the Max 10 FPGA development board was repurposed for Tangerine SDR Development. An adapter board was designed that allows the Clock Module and RF Module to be interfaced to the Max 10 development board for Verilog development of the Tangerine SDR. Since the LEAF module is too large for the adapter board, the adapter board will include a connector to interface the TI TLV320ADC6140 Evaluation (DUT) board. The DUT board includes the TLV320ADC6140 and all supporting circuitry to spearhead Verilog development of the VLF LEAF module. The FPGA will add GPS timestamping to the recorded samples and reformat the stream to be compatible with vlfrx-tools, an open source signal processing tool set with many applications, including VLF/ULF signal processing.\ 

}, author = {Jonathan Rizzo} } @proceedings {461, title = {VLF Module for Tangerine SDR Progress Update}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, address = {Scranton, PA (Virtual)}, abstract = {

The VLF Audio Module for the Tangerine SDR has had a design change and now features the TI TLV320ADC6140 4-channel Analog to Digital converter. It features 113dB dynamic range with sampling rates of up to 768kHz. Using a sampling rate of 384kHz, bandwidths of up to 100kHz of VLF spectrum can be captured and will be GPS timestamped by the Tangerine SDR. This design change{\textquoteright}s increase bandwidth capability allows for not only study of natural radio emissions such as whistlers and chorus, but study of the ionosphere with the help of measurements from VLF transmitters in the middle and upper VLF band, such as WWVB.\ \ 

}, author = {Jonathan Rizzo} } @proceedings {494, title = {W3USR and The Great Collegiate Shortwave Listening Contest}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, address = {Scranton, PA (Virtual)}, url = {https://hamsci2021-uscranton.ipostersessions.com/Default.aspx?s=1B-12-5C-9B-5C-AF-F5-8B-AC-62-CD-DD-D5-51-6A-9A}, author = {M. Shaaf Sarwar and Veronica I. Romanek and Thomas Baran and Jonathan Rizzo and Steve Holguin and Jonathan Rizzo and Nathaniel A. Frissell and William Liles and Kristina Collins and David Kazdan} } @conference {402, title = {Using a PVC Pipe Antenna and a Raspberry Pi to Detect VLF Natural Radio (ePoster)}, booktitle = {HamSCI Workshop 2020}, year = {2020}, month = {03/2020}, publisher = {HamSCI}, organization = {HamSCI}, address = {Scranton, PA}, abstract = {

It{\textquoteright}s possible to detect half of the world{\textquoteright}s lightning anywhere on Earth. Because most of a lightning discharge{\textquoteright}s spectral power is within the Very Low Frequency (VLF) and Ultra Low Frequency (ULF) bands, the emissions from lightning discharges (sferics) propagate rather easily across the globe. These propagation conditions allow for other natural radio events like tweeks, whistlers, and chorus to propagate well within the Earth-ionosphere waveguide. Using a simple E-Field VLF receiver, a GPS timing receiver, a Raspberry Pi with Audioinjector soundcard, it is possible to build a fully contained low power VLF reception system to detect natural radio events in the VLF/ULF band using open source software that will capture, GPS timestamp, and filter (remove mains hum) the VLF audio feed and record, detect individual events, detect sudden ionospheric disturbances, and perform analysis on detected events. VLF event data, recordings, and live streaming is possible, all from a PVC pipe active E-Field antenna receiver, GPS timing receiver, and a Raspberry Pi.

}, author = {Jonathan Rizzo} }