ARRL Frequency Measuring Test (April 2021)

The Case Amateur Radio Club W8EDU participated in the Frequency measuring test this past week, scoring with less than 2 Hz error on all frequencies. Our best score was on 7 MHz, where the club scored an error of just 10 millihertz, or a little over 1 part per billion!

Operating the station were Frankie Bonte KE8HPA, Adam Goodman KJ7RPK, Sergei Prokvolit KE8QFY, and Skylar Danhoff KD9JPX.

We also had several current and former club members participate, including David Kazdan AD8Y, Jim Galm W8WTS, and John Gibbons N8OBJ. We especially congratulate John, who scored in the infamous green box for less than 1Hz error on all frequencies!

We hope to see everyone at the next Frequency Measuring Test!

W8EDU Presents at HamSCI 2021

We had another large showing from the Case Amateur Radio Club at HamSCI 2021, which was held virtually this year on March 19-21.

W8EDU members were involved in (in the order that they appeared in the program):

Kristina Collins KD8OXT served on the science/program committee that selected topics for the conference.

PSWS Grape Hardware: Version 1.0 and Pilot Experiments  Kristina Collins KD8OXT

PSWS Grape Hardware: The Second Generation John Gibbons N8OBJ

David Kazdan AD8Y served as moderator for a discussion section.

Kristina Collins served as the chair of the third session of talks, as well a brand-new experimental co-design session.

December 2020 Eclipse Festival Analysis Kristina Collins KD8OXT

Data Collection from WWV, WWVH, and WWVB: A Histoanatomy of NIST’s Radio Beacon Transmissions David Kazdan AD8Y

RJOVER: An alternative approach using SDR technology to reduce costs for the NASA Radio JOVE citizen science effort  Skylar Dannhoff KD9JPX

W8EDU: Case Amateur Radio Club from 2010 to 2021 Aidan Montare KB3UMD and Kristina Collins KD8OXT

The full conference program, with links to recording of the sessions, slides, and posters, is available at https://hamsci.org/hamsci-2021-program. (Eventually, edited videos of each presentation will be available on this page, but for now, the full recordings of each session are available.)

Collaboration with Case Rocket Team: A Retrospective

A little over a year ago (2019 into early 2020), we had the pleasure of being consultants to the Case Rocket Teams, one of the competitive student project teams at CWRU.

The rocket team sought to transmit video from their rocket during flight and receive it on the ground. They had purchased an initial set of equipment and performed a test run, but the initial results were not encouraging.

Video from the rocket could only be seen when it was on the ground, the signal was far too noisy to make out anything when the rocket was in flight. So the rocket team sought out us as consultants to see if we could improve the situation.

We met with them, and after learning about our client’s needs, came up with some ideas, including different antenna choices for transmitter and receiver. Together, we all decided that a ground-based test would be the best way to verify our choices.

We started by taking antennas out to the engineering quad, and testing them at short distances. We were able to observe some effect, and made some predictions about what would work best, before moving on to a full scale test that would match the distance the rocket would travel when in flight.

The receiving site during our ground test.

Rocket team members identified a stretch along the Lake Erie waterfront that was the same length as the rocket’s expected maximum altitude. We divided into groups, and send one group with the transmitter (which would be in the eventual rocket) to one end of the path, and the other group with the receiver to the other end. Both groups brought several antennas to test with.

The path along the Cleveland waterfront where we tested antenna combinations.

It was a beautiful day, and we had a clear view across the water to the other group’s site (they were just barely visible in our binoculars). We qualitatively identified how well the system was working by watching the video quality on a laptop at the receiving end.

We were able to identify the effects of signal polarization, antenna gain, and antenna patterns on the received signal. We identified what seemed to be the best combination of antennas and even managed to go to the farmers market afterwards!

The day was a lot of fun, and it was nice to see the concepts we knew play out as we held the antennas.

We also calculated a rough link budget that agreed with what we saw in our tests.

On the rocket team’s next practice launch, they were able to record video and demonstrate that our changes had in fact improved the quality of the video! Unlike before, they could now see almost all of the flight, with only a brief interruption as the rocket rotated at the peak of its travel.

Unfortunately, we weren’t able to see the improved solution fly in competition (if memory serves, this was because the competition was later in the year and was canceled due to COVID-19). However, we still achieved our technical goals, and made some friends in the process. We hope to see the live video system in flight in competition, but in the meantime, check out the Case Rocket Team website, they’re awesome!

—Aidan Montare, KB3UMD

Radio-related Senior Projects (Spring 2021)

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.

the dual dipole array at the CWRU farm (special guest star: Skylar)
our data collection setup using the existing Radio JOVE kit with the laptop/kit receiver/kit calibrator
our RaspberryPi (without the RTL-SDR)
an example of GnuRadio block code we will develop to replace the kit hardware

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!

the Yaesu radio we hope to modify
a Leo Bodnar GPS-disciplined oscillator of the kind we hope to use to control the radio’s crystal
Planned circuit for the project. The crystal frequency is divided down to 1 pulse per second, and then compared with the signal from the GPS using a phase comparator.

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

W8EDU joins College Ham Club Roundtable

Club president Aidan KB3UMD participated in a panel discussion of college amateur radio clubs hosted by the Radio Amateur Training Planning and Activities Committee (RATPAC). RATPAC brings together ARRL leaderships and members for training events and presentations, and we were happy to share a bit about college radio with this group!

You can find all the RATPAC presentations on their YouTube channel, or their website.

Exploring Bit Error Rate with FLDigi

CWRU Comm Lab

Today’s recommendation for teachers: A fun demonstration of bit error rate if all you have to work with is an A/V system and some laptops, sending text and images via audio using various digital modes in FLDigi. We used this demo in this morning’s EECS 351 (Digital Modulation) class, sending text and images from one end of the classroom to the other using only audio. Having a good microphone at the receiving end is helpful, but with a bit of adjustment it’s possible to use the built-in microphone in most laptops.

https://lh3.googleusercontent.com/-ax5SM1a3jO4/Wr0G1yqElOI/AAAAAAAAKIY/TV07q4JctAoceSqeyjl0qfbxKr1KbrNSACL0BGAYYCw/h1536/4077629013166858715%253Faccount_id%253D1

We sent text over BPSK, QPSK and 8-PSK and compared the error rates of the different modes. This was the sample text we used:

Parkin was quoted in an article titled “The Feminine Wireless Amateur,” which appeared in the October 1916 issue of The Electrical Experimenter:

“With reference to my ideas about the wireless profession as a…

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