This semester we’re fortunate to see a number of radio-related senior projects! These are the ones I know of, let us know if there are others.
Most of the projects below are receiving support from the Case Amateur Radio Club. If you’re a student with a project coming up, keep us in mind—the radio club can often provide equipment to borrow, and you are always welcome to contact us for advice and suggestions!
RJOVER – RadioJOVE Revised
Jared May, Skylar Dannhoff, Tyler Kovach
The NASA-run citizen science project, Radio JOVE, utilizes widespread distribution of single and dual-dipole antenna receiving stations to study the magnetic interactions between Jupiter and its moon, Io. The antennas, receiver, software, and related components are available for purchase in Radio JOVE kits that range in price from approximately $95 and $225 (excluding the cost of an external computer required for data collection). To further data collection accessibility and broaden the participating audience, however, we seek to further reduce these costs—specifically that of the receiver—for an overall cost of just $95. On the hardware front of the project, we have successfully erected a dual dipole array that currently resides at the Case Western Reserve University (CWRU) Research Farm. This setup is actively receiving radio signals from the Milky Way galaxy and surrounding radio sources so we have measurements of how “radio quiet” our site is. If our radio background noise level is low (which so far it seems to be), we will begin listening for radio storms produced by Jupiter and Io at a peak frequency of 20.1 MHz. These radio storms are a result of Io spewing out charged particles into space from its active volcanoes. These charged particles get swept up into Jupiter’s strong magnetic field and consequently produce lots of cyclotron radiation between 10 and 39.5 MHz. Our group has also successfully been able to receive 20 MHz signals from WWV on a Raspberry Pi/RTL-SDRcombo setup using a software interface, GQRX. Our next steps involve translating the Radio JOVE supplied receiver’s hardware into software using GnuRadio. Soon after we will replace the kit receiver with the Raspberry Pi/RTL-SDR and continue listening for Jovian radio storms but through our cheaper, smaller, and software-defined solution.
An Approach for Minimally-Invasive GPS Frequency Control in Amateur Transceivers
Aidan Montare, Zachary Reinhold, Matthew Levy
Advised by: Dr. Marc Buchner and Dr. David Kazdan
The Case Amateur Radio Club is actively involved in a number of scientific projects that use radio to study the ionosphere (a part of earth’s upper atmosphere). For many of these experiments, we need to make accurate measurements of a target signal’s frequency. For example, an HF signal nominally at 10 MHz must have its frequency measured in the milliHertz range in order to detect the small variations caused by changes in the atmosphere during the day.
The radio club owns two HF (high frequency) transceivers. Like most communications receivers, they provide accuracy in the 1 Hertz range, which is suitable for communicating with others, but not for scientific measurements. The newer of the two has an input connector for an external frequency reference, allowing the radio to be controlled by a more accurate time source. The older radio does not. The radio club would like this older radio to be made accurate enough in frequency that it too can be used for the club’s scientific projects, while retaining its usefulness for general communications.
In this project, we will develop an easily-constructed method for placing the crystal oscillator of this older radio under GPS control. We will do this using a phase locked loop built around the crystal, which will hopefully improve accuracy and also be an easier modification than replacing the crystal entirely (which many amateurs might be hesitant to do). We look forward to developing this project and sharing a procedure with the amateur community!
3 cm Transverter for the Amateur Radio Emergency Data Network
JP Mappes, Jason Paximadas, and Joshua Volmer
The Amateur Radio Emergency Data Network (AREDN) is an organization of HAM radio operators who build high bandwidth mesh networks on the 33 cm, 13 cm, 9 cm, and 5 cm bands. AREDN operators use off-the-shelf 802.11 modems in an “Ad Hoc” mode to accomplish this task. As a result, AREDN inherits the software support and IP stack that comes with any 802.11 modem. This includes common VoIP protocols, video calling, chat rooms, and websites.
However, the bands most off-the-shelf modems have access to are becoming crowded which constrains bandwidth. Additionally, the 9 cm band is being taken away altogether. Many AREDN users would like to move off these bands to the underutilized 3 cm band. The trouble is that this move would render most existing AREDN infrastructure worthless. Compounding this issue is the high cost of 10 GHz 802.11 modems.
Our team has decided a transverter would be the best option to solve this problem. A transverter mixes an incoming signal with a local oscillator to shift it in the frequency domain. In practice, it can be inserted between a 3 cm dish and an AREDN modem, up-converting signals from the modem and down-converting signals from the antenna. Ideally, this would allow an AREDN modem to operate on the 3 cm band transparently. Although HAM radio operators have designed transverters which transmit/receive on 3 cm, these systems are usually meant for narrowband analog signals. The wideband modulations used by 802.11 modems would be severely distorted by the filters used in those designs.
If the circuit turns out the way we want it to AREDN will have a turn-key solution for retrofitting existing infrastructure to utilize the 3 cm band.
Simulation of distributed element filter used in the transverter