Interviews

Interview with HamSCI Founder, Dr. Nathaniel Frissell, W2NAF (Part 2)

Posted by on October 11, 2023 at 5:31 pm

We’re back with HamSCI founder, space physicist, electrical engineer, university professor, and longtime ham who we could easily include more titles and accolades for based on his many contributions to radio science, Dr. Nathaniel Frissell, W2NAF. In part two, he fills us in on current HamSCI projects; how upcoming experiments will connect with the October 14, 2023, and April 8, 2024 solar eclipses; ionospheric disturbances; and how his studies brought him to a locale with a greater populace of polar bears than people.

Can you tell us more about the 2023/2024 solar eclipses and the Sources and Measurement of Traveling Ionospheric Disturbances projects your team is currently working on?

Eclipses
Both of these are extremely exciting projects. There are two solar eclipses that will be taking place over North America. The first will be an annular eclipse on October 14, 2023, and the second will be a total solar eclipse on April 8, 2024. These are rather rare events; the next solar eclipse over the continental United States will not be until 2044. When a solar eclipse occurs, the moon’s shadow prevents sunlight from reaching the upper atmosphere. Because the ionosphere is driven by photoionization, the ionosphere and radio propagation will be affected. This has actually been known for a very long time, but we continue to study it because there are still so many details about the ionosphere that are unknown. Every eclipse is unique in that they all travel in different directions and occur at locations on Earth and at different points in the solar cycle. While eclipses can be thought of as “temporary night,” there are also differences from the incidence of actual “night” in that eclipse shadow is point-like, and it moves faster than the dawn/dusk terminator. All of these factors make eclipses interesting to study scientifically.

HamSCI is conducting many different experiments for the upcoming eclipses all of which fall under what we call the Festivals of Eclipse Ionospheric Measurement (FoEIS). More information can be found at https://hamsci.org/eclipse. Perhaps the best known and most accessible experiments are the Solar Eclipse QSO Parties. These are science experiments that are really set up like a traditional ham radio contest with the main goal to get as many signals on the HF bands as possible before, during, and after the eclipse. Stations will compete for points, and the scientific data will be the submitted logs and the spots automatically received by PSKReporter, the RBN, and WSPRNet. These results will be compared to a physics-based model of the eclipsed ionosphere. Our Gladstone Signal Spotting Challenge (GSCC) is related to the SEQP, but awards points for spotting stations using RBN/PSKReporter/WSPRNet receivers that operators set up rather than for making QSOs. We were successful with the SEQP approach during the 2017 eclipse and were able to publish the results in the peer-reviewed journal Geophysical Research Letters (https://doi.org/10.1029/2018GL077324).

The Grape Personal Space Weather Station (PSWS) is another popular project to study the eclipses. See https://hamsci.org/grape. In this project, participants are building and fielding specialized HF radio receivers that monitor transmissions by WWV and WWVH. The signals transmitted by both these stations have atomic-clock grade frequency precision and accuracy. The Grape receivers use GPS disciplined oscillators (GPSDOs) to enable the system to make frequency measurements that are much more precise than any typical amateur radio on the market today. While this level of precision is not necessary for routine communications, it does enable the measurement of interesting ionospheric variability that would normally go unnoticed. The Grape receivers will often observe variations in the WWV/WWVH carrier on the order of one Hz or more. These variations, which we call HF Doppler shifts, are due to changes in the propagation path length caused by a moving ionosphere or changes in ionization along the propagation path. Positive Doppler shifts can be observed every morning as the sun rises and the ionosphere builds up and negative Doppler shifts occur each evening. Solar flares, traveling ionospheric disturbances, and eclipses also cause measurable Doppler shifts.

Hams who want to transmit but are interested in a more precise experiment than the SEQP should check out the HamSCI Time Difference of Arrival (TDOA) experiment (https://hamsci.org/tdoa-event-2023). In this experiment, amateurs are able to transmit brief chirps to each other within a typical SSB bandwidth (~3 kHz) and record the received signals for later analysis. If HF multipath is present, the received signal will have an amplitude pattern that can be used to estimate ionospheric layer height of refraction. One of the advantages of this particular technique is that it can produce a unique ionospheric measurement using standard amateur radio gear; no GPSDO is required. In addition to our HF eclipse work, HamSCI is also supporting research using Very Low Frequency (VLF) receivers and observations of medium wave AM broadcast signals (https://hamsci.org/mw-recordings/).

Traveling Ionospheric Disturbances
Traveling ionospheric disturbances (TIDs) refer to a certain type of wave-like variations that occur in ionospheric electron densities. TIDs can affect HF amateur radio operations by causing QSB, or fading, with periods that can range from 15 minutes up to about four hours. The fading is caused by the TID either focusing or de-focusing the transmitted radio signals to different locations on Earth. As the TID moves overhead, the location of the focusing changes. A receiver that is located in a region where the radio waves are focused will hear a strong signal. TIDs are also of scientific interest in that they are often associated with atmospheric gravity waves (AGWs)—or waves in the neutral atmosphere that can transport energy and momentum over large distances from one atmospheric region to another. A big debate is whether TIDs are caused by disturbances from space (e.g., auroral disturbances and geomagnetic storms) or by sources in the lower and middle neutral atmosphere.

My interest in TIDs started in graduate school when I was asked to look at medium-scale TIDs (MSTIDs) using SuperDARN radars. MSTIDs refer to TIDs with periods between 15 to 60 minutes, horizon speeds of ~100 to 250 m/s, and wavelengths of several hundred kilometers. The main result of my PhD research found that daytime MSTIDs over the continental United States and Canada all typically occurred in the late fall and early winter and predominantly moved in a southward direction. It was also found that there were aperiodic multi-week events in which TID activity decreased. Very poor correlation with auroral and geomagnetic activity was observed. Instead, a strong correlation with polar vortex activity was observed, supporting the hypothesis that these MSTIDs are primarily associated with lower/middle neutral atmospheric sources.

Because of the technical similarities of SuperDARN ground scatter measurements and HF amateur radio communications, I believed there was a good chance we could also observe TIDs using the amateur radio network. It turns out that we could see large-scale TIDs (LSTIDs) by looking at the variations of the first hop-skip distance in combined RBN, PSKReporter, and WSPRNet data. We published this in Geophysical Research Letters in 2022 (https://doi.org/10.1029/2022GL097879). LSTIDs have periods between about 30 minutes to three hours, horizontal wavelengths greater than 1000 km, and horizontal speeds between 400 to 1000 m/s. MSTIDs also, likely, affect amateur radio signals, but the RBN/PSKReporter/WSPRNet data is too noisy to easily see this. In the GRL paper, we looked at a single LSTID event and found that it was likely due to an auroral disturbance. We are now working on statistical studies of LSTIDs using the amateur radio data and comparing it with other observations and models including SuperDARN MSTID measurements. From what we can see so far, it looks like there is good evidence that both the polar vortex and auroral activity can cause these LSTIDs. The polar vortex influence is a bit of a surprise which makes the work very interesting. These are still preliminary findings, but we are currently working hard to understand what is happening and publish the results.

You mention that recent advances in the fields of computing, software-defined radio, and signal processing are providing new opportunities in the field of radio science (Reverse Beacon Network, Weak Signal Propagation Reporting Network, and
PSKReporter)—can you elaborate on this?

Before computers, digital signal processing (DSP), and software defined radio (SDR), people had to build specialized analog circuits that could only deal with signals in one particular way. If you wanted to analyze them differently, you needed to build a different and possibly more complex circuit. Many of these circuits could only handle one narrowband signal at a time. With modern techniques, it is possible to record and digitize large portions of the RF spectrum for later playback and analysis. This data can then be analyzed in any multitude of ways and multiple signals can be demodulated and processed simultaneously. This has led to an entirely new modulation scheme and ways of processing the data.

It is also important to realize that we are trying to study a global-scale system, which means that we need as many measurements from as many places across the world as possible. The development of the high-speed internet has made it possible to easily share all these observations, and the development of high-capacity hard drives and high-performance computers and analysis algorithms have made it possible to turn this large amount of data into useful information and scientific advances. The RBN, WSPRNet, and PSKReporter (which all started ~2008) would not exist without these advances. Today, you can also live-stream raw RF observations from anywhere in the world. The KiwiSDR network (http://kiwisdr.com/) is a great example of this.

Has your team thought about future projects? What would those look like?

Of course! For me, though, the most important thing at the moment is bringing some maturity to the PSWS network and getting good science results out of this. There will be so much to do once we have a good, solid stream of observations coming in from that project. I am very interested in comparing these observations to models and also figuring out how this information could help advance ham radio.

If you had unlimited funding for your organization (I’ve heard some recent grants have been quite substantial), what new projects would you be excited to undertake and why?

In addition to the continuation of the projects we already have going, I’m very interested in being able to scale up HamSCI in such a way that we can really help amateurs in the community participate in and do radio science themselves. Most people are able to start as a data collector relatively easily, but it actually takes a lot of training, study, and mentorship to know how to analyze and use that data and then publish the results. It would be great if we really had the resources to help educate large numbers of people so that they could do that.

Can you tell us about the work you did during the SuperDARN and Automated Geophysical Observatory build and repair expeditions on Adak Island in Alaska and at McMurdo Station, Antarctica during your studies at Virginia Tech?

I was really fortunate with my travel during both graduate school and when I was a post-doc and research professor! I think the first really big trip was in 2010 when I was able to spend a semester at the University Centre in Svalbard (UNIS). While there, I took two courses for my PhD: Upper Polar Atmospheric Physics and Incoherent Scatter Radar. I first heard about Svalbard when I was in high school and worked JW7M. When I told my local radio club about it, they said, “Wow, Svalbard! That’s a really special place. There are more polar bears than people there.” My father was really intrigued by this, and he made the joke that I should go to college there. Little did he know that I someday would :-). I was able to return to Svalbard in 2014 for a conference and worked CQ WPX CW from JW5E while I was there. I ended up winning all of Svalbard for both the 2014 CQ WPX and the ARRL Centennial QSO Party.

I’ve been to McMurdo station twice. The first (2014) was during grad school to help repair the McMurdo SuperDARN antenna that had a broken support tower (see photobook). A neat thing that happened on that trip was that I got to be part of the McMurdo Station Christmas Choir. All of the stations would sing songs to each other on the 7995 kHz operational HF frequency. We sent out a news release through the ARRL and had people all over the world listen for us. I got QSL cards and recordings sent to me from all over. The second time was in 2017 when I mostly did computer programming work for Automated Geophysical Observatory Magnetometers.

I spent three weeks on Adak Island in 2013 helping to build the SuperDARN radars there. It was a very different experience than both Svalbard and McMurdo since the island is mostly abandoned. There is a small population there that keeps things going. My friends and I did bring a ham radio station with us, so we were able to work a mini-DXpedition in our off hours. I got that written up for CQ Magazine.

You’ve likely met some interesting and well-informed hams in your line of work. Who has made the most memorable impression and why?

You are right… there are so many amazing people that I can’t pick a single person who is “most” memorable! But, I will tell you about one of the very memorable people. Jules Madey, K2KGJ, appeared on the HamSCI Google Group seemingly out of nowhere about four years ago. He became an extremely important contributor to our ground magnetometer project. I eventually learned that he had a ridge in Antarctica named after him for the phone patches he ran as a teenager in Clark, New Jersey in the 1950s and that he also invented EZPass. See:

I’m sorry to say that Jules became a Silent Key this past March 2023. I dedicated the HamSCI workshop to him this year.

In what ways do you expect the work from your three current projects to influence amateur radio?

I think these projects are going to impact amateur radio in many, many ways. I think we will see the advancement of scientific knowledge, the development of new hardware and software, a community increase in the knowledge and awareness of propagation and ionospheric science, and an increase of amateur radio participation in research endeavors.

You’ve served as a mentor to Boy Scouts of America in the past. The amateur radio community is always looking for ways to expand youth involvement in amateur radio. What are your recommendations (if any) to increase involvement and boost certification among young people?

I think there are a couple of parts to this:

  1. Have enthusiasm yourself for what you are doing.
  2. Understand what interests (young) people and what would make amateur radio relevant to them.
  3. Provide structured and accessible opportunities for them to be involved.
  4. Provide resources to help them continue to learn once they have an interest.

I think a lot of young people don’t know what amateur radio is or why they should care. Good mentorship (Elmering) at the individual level can help with this. So can structured programs run by schools, clubs, and organizations like the ARRL.

Do you have any photos you would be willing to share about your amateur radio experiences?

Sure! I’ve included links to photos from many of my trips above. More good photos can be found at:

Our sincere and many thanks to Dr. Nathaniel Frissell for being kind enough to share his expansive amateur radio knowledge, experiences in the field, updates on HamSCI, and thoughts on the best ways for hams of all ages to get more involved. 73!

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