Tag Archives: HamSCI

Beyond DXing: Analyzing Medium Wave Propagation During the 2023 Annular Eclipse

The following article dives into medium wave (MW) radio propagation during the 2023 annular solar eclipse, building upon insights from the 2017 total solar eclipse when DXers made broadband radio recordings of the whole MW band for the first time. Unlike that previous study, the 2023 research took a methodical approach, with standardized data collection, stable receivers, and GPS-synchronized frequency locking. Thirteen radio enthusiasts across North America and Europe contributed to the study, capturing 10 Terabytes of SDR data. Using Carrier Sleuth software, researchers pinpointed key signal strength variations, with some regions experiencing remarkable boosts in signal during the eclipse. These findings highlight how eclipse-induced propagation effects are not the same as those seen during typical sunrise and sunset transitions. The study opens doors for further exploration into whether these effects are symmetrical and how they might relate to ionospheric thinning along specific signal paths. The article ends by asking assistance from DXers to help ID enhanced signals in the 2023 eclipse data sets.

Medium Wave Monitoring During the 2023 Annular Solar Eclipse—Not Just About DXing

By Nick Hall-Patch, VE7DXR

Background

The 14 October 2023 annular solar eclipse was the first one to cross the continental United States since the total eclipse of 17 August 2017. From a DXing standpoint, 2017 was the first eclipse in which there was widespread use of software defined radios (SDRs) to record the entire medium wave (MW) band throughout the duration of the eclipse. Therefore, it was possible to study eclipse receptions after the fact rather more than had been the case during earlier ones. Several IRCA members recorded the 2017 eclipse on their SDRs, and in the months after the eclipse, data files from several locations were examined. It was therefore possible to evaluate the varying signal strength of KSL-1160’s carrier from four different locations in western America, all from outside the path of totality, and to speculate upon the differences in the responses at each site.

That study of KSL’s strength variations during the eclipse led to a presentation at the St. Louis IRCA/NRC convention in 2018, and eventually to an IRCA Technical column (now IRCA Reprint G-096 at http://dxer.ca/images/stories/2019/irca-reprint-index.pdf) which proved to be of interest to HamSCI, an amateur radio citizen science group that had already been using amateur radio communications as a way to study that eclipse’s effects upon the ionosphere. A version of the article appeared on HamSCI’s website and the SDR files referenced by the article were also hosted by the HamSCI community on zenodo.org, along with SDR data from three further locations in eastern America. (Go to zenodo.org, and search on the phrase “Solar Eclipse 2017 recordings” to examine this data for yourself.) Zenodo is a long-term open repository for scholarly work, and these data sets have since been downloaded hundreds of times.

Why would these 2017 SDR files have been of interest to an organization studying radio wave propagation? Unlike the short duration communications found on the amateur radio bands, medium wave (MW) AM broadcasters, assigned between 525 and 1705kHz, provide continuous signals, many for 24 hours a day. Their carrier frequencies are like steady RF beacons. Any changes in that beacon’s amplitude or frequency at a receiver are likely to have been caused by changes in the path between transmitter and receiver. By using suitable hardware and software, either monitoring a single frequency or the entire medium wave broadcast band using SDRs, the resulting files can allow us to characterize the propagation induced changes that these carriers undergo over time, including variations in signal strength and apparent shifts or spreading in the frequency of each carrier. During a solar eclipse, the brief period of darkness along the path of the eclipse can allow AM broadcasters’ signals to temporarily travel much further than they would normally in the daytime, and it is possible to study variations that occur even more quickly than those occurring daily during sunrise and sunset.

Preparation for the 2023 Solar Eclipse

From a DXing standpoint, the 2017 eclipse SDR files were more than functional, but a closer examination revealed gaps in the data, changes of antennas when it suited the DXer, and receivers that had not been properly warmed up, resulting in recorded carriers that appeared to be drifting. From the standpoint of a scientist, this was “found data” requiring judicious handling and compensation. In addition, the data had been transferred many months after the recording had taken place, and sometimes it was no longer clear how the receivers and antennas had been set up for the recording.

Nearly a year before the 2023 eclipse, HamSCI had decided that it would be interested in examining more MW SDR data, but this time asking that the recording of the data be approached in a more professional fashion. In other words, participating DXers would be asked to think a bit more like scientists for the duration of the recordings. Making recorded IQ files of optimum use to propagation researchers would include the following:

Documenting receiver, software and antenna used, with as many details as possible.
Not making changes in receiver or antenna configuration during the recording period; if absolutely necessary, recording that change in detail, especially the time that it occurred.
Warming up the receiver for several hours before recording in order to minimize apparent carrier drift in recorded signals. Better yet, encouraging participants to use SDRs that were locked to a frequency standard such as the Bodnar GPS reference clock, because a frequency locked SDR’s data would display frequencies with stability and accuracy, and allow characterization of any carrier Doppler shifts.
Making sure that timestamps in their recorded data were as accurate as possible, at a minimum setting the computer clock accurately immediately before recording, and preferably to use a network time protocol (NTP) time client on the computer that would be recording the SDR IQ files.
Starting recording well before maximum totality in their area, until well after that time; one hour before the start of the partial eclipse to one hour after the end of the partial eclipse were suggested as a minimum.
If possible, making additional SDR recordings of, for example, the period from two hours before and after sunset and sunrise on the day of the eclipse, and also making a reference recording of the eclipse time period on another day.

Figure 1 shows the path of the 2023 eclipse and the times of maximum obscuration. Efforts were made to involve monitors in both North and South America, and in the end, 13 participants were involved in the experiment, using 14 sites in Canada, the USA, Mexico and Portugal.

Figure 1

12 sites also included data from local sunrise (LSR) and/or local sunset (LSS)
12 sites also recorded data from the same time as the eclipse period on another date in order to provide a reference of a normal day’s reception conditions
6 sites produced data using an SDR locked to a frequency standard that was disciplined using GPS signals. Three of the remaining sites included a signal from a frequency standard in their data recording.
10 sites recorded using computers that had their clocks updated using Network Time Protocol (NTP); others set computer time manually

About 10 Terabytes of SDR recordings were submitted for analysis, which is one heck of a lot to poke through in order to find signals fading up and down for a few minutes during the course of the eclipse. Fortunately, it was possible to pre-process all of the files using Carrier Sleuth software which allowed visualization of hours of data at a time from each MW channel, all available to 0.1Hz resolution over an 80Hz span centered on each broadcast channel. It was then a fairly quick process to scan through each of the 117 channels of the AM broadcast band for each data set, searching for unusual carrier enhancements appearing during the eclipse time period.

An example is shown in Figure 2, portraying 1650 kHz as logged during eclipse enhancement in Phoenix, AZ by Burke Baumann KF7NP. The thin lines representing various carriers are represented in “hotter” colors when signal strength increases.

Figure 2

Because Carrier Sleuth can rapidly generate a chart for signal strength vs. time for each individual carrier, it was decided arbitrarily that a carrier that increased in strength by at least 10dB during the duration of the eclipse at that site would be deemed to have been influenced by the passage of the moon’s shadow. By that metric, six sites indeed reported that during the eclipse, different broadcast signals appeared from those normally received in the daytime. However, other sites did not, or received only a few traces of carriers during the eclipse period.

Figure 3 shows the various sites that submitted SDR data, indicated by pale blue circles, and within each circle is the number of AM broadcast band channels on which eclipse effects were noted, even if it was just a carrier.

Figure 3

From Figure 3, it can be seen that locations in Canada’s west and in the south and west of the USA were likely to have been influenced most by the passage of the eclipse. In contrast, it appears that those who were in locations of less than 50% of totality were unlikely to have seen much effect from the passage of the eclipse. Continue reading →

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How to DX the 2024 Solar Eclipse!

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Many thanks to SWLing Post contributor, Nick Hall-Patch, who shares the following article originally published in the IRCA’s DX Monitor:

2024 Solar Eclipse DXing

by William Scott, WE7W

DXing the mediumwaves promises to be an exciting event on April 8 during the 2024 total solar eclipse. I’ve been mulling over the DX possibilities a lot lately and have come to some conclusions. I think it boils down to three promising DX scenarios:

Scenario 1. For those who live within or very near the path of totality (see Figure 1), I believe best chances of DX would be first to listen to your southwest, along the path where totality is approaching. Darkness will already have happened in that direction, and a certain amount of residual de-ionization of the ionosphere will still remain. After the point of totality passes your location, I would swing my attention to the northeast.

Scenario 2. For those living within about 800 km (or about 500 miles) of the path of totality I believe best chance would be a perpendicular path across the totality path to a point roughly equidistant on the other side. This puts the signal reflection point right at the center of the totality path, or the deepest point of darkness.

Scenario 3. For those living more than about 800 km from the path of totality I believe best chance would be along a line from your receiving site to a perpendicular intersection to the totality path. This should define the greatest shaded path.

I think that scenarios #1 and #2 have the best possibility for DX.

Figure 1 (Click to enlarge)

Across the U.S. and Canada, from its entry at Texas to its exit through NE Canada and into the Atlantic Ocean, the totality path width varies from a maximum of 199 km at U.S. entry to about 160 km at Atlantic exit, or 123 to 99 miles.

Important to keep in mind – skywave signal strength analysis is based almost entirely on the condition of the ionosphere at the reflection point, not at the receiving site. For single hop propagation, normally the reflection point is at the halfway point to the station along the great circle route. That 800 km distance from the totality center I wouldn’t hold as gospel. I’m throwing that figure out as a point where scenario #2 may start to transition to scenario #3.

Timing is of the essence for DXing. The shadow velocity exceeds 1000 mph, increasing from 1587 miles per hour at Eagle Pass, Texas to 3176 mph at Houlton, Maine. You may have only minutes to DX. I’ll be in Rochester, NY at the time of totality, and we are right at dead center. I’ll be scenario #1. My plan is to listen to my southwest initially, where totality is approaching. I’ll be listening particularly for WLW-800 in Cincinnati, OH, WHAS-840 in Lexington, KY, and others along or near that path.

Scenario #2 possibly holds the most promise. Calculate your distance to the path center line and look for stations on a direct line across the totality path and at an equal distance on the opposite side of the path from you. One such scenario might be WSB-750, Atlanta to a reception point in northwestern Illinois, central Iowa, or southern Wisconsin or southern Minnesota. Many possibilities on cross-paths exist here. I feel best results would be with a signal path that crosses the path of totality closest to 90 degrees.

A question was raised about the possibility of DX from Spokane, Washington, an extreme distance from the path of totality. That particular scenario would be scenario #3, more than 800 km to the path of totality. Maximum obscurity should be when northeast Texas (let’s say the Dallas area) is experiencing full totality, as the great circle line to the totality path intersects at approximately 90 degrees to the line at that point. This would be at about 1848 UTC. I would listen for any signals along a great circle path between Spokane to anywhere from the Dallas area and northward. Obviously, Spokane to Dallas is an extremely long one hop path, at about 2450 km. At that distance, the reflection point is near Denver, which will have a solar obscuration of 65.1% at maximum.

A Dallas area reception would be next to impossible I would think, but there are many more stations along that great circle path one could try for. Closer stations will obviously move the reflection point closer and start to reduce the solar obscurity. I did a scan along that path and there are some 340 stations within 200 km either side of the line of the great circle path between Spokane and Dallas.

A presumed Scenario #4.

Another scenario was suggested by Nick Hall-Patch, that of reception parallel to the path of totality and outside the 100% totality band. The 2017 solar eclipse across the northern part of the U.S. was DXed extensively and produced some interesting results, which are well documented in IRCA Reprints. Check their document repository here:

http://dxer.ca/images/stories/2019/irca-reprint-index.pdf

Nick reports: “The receptions of KSL-1160 described in IRCA Reprint # G-096 showed the results of 3 DXers listening across the path of the eclipse (Scenario #2), but the fourth, Dave Aichelman, was monitoring KSL from a location parallel to the eclipse path ( sort of Scenario #1?) and got very good enhancement as well.” We might name this “Scenario #4”.

I checked out # G-096, that documents the KSL reception from the solar eclipse of 2017. It looks like the Dave Aichelman (at Grants Pass, OR) reception of KSL had a mid-path reflection point of about 95% solar obscurity. The distance was 971 km (602 miles). Graphing KSL, I see it has a nice fat low angle takeoff and impressive skywave strength at 900 km, some 1.3 mV/m for that distance. (ed. note: A map of fractional solar obscuration is in Figure 2, easily converted to the percentage figures quoted in this article. )

Better yet, the article indicated Aichelman also received XEPE-1700 across the Mexican border from San Diego too. That was a mid-point reflection obscurity of only about 83% as far as I can deduct from the maps. The distance was 1238 km (769 miles). The mid-path reflection point there was in the neighborhood of 700 km from the central path of totality.

So, DX is indeed possible where both the station and the receiver are off center from the totality path. It’s looking like anything from at least 80% obscurity at mid-path reflection may have some real possibilities, particularly if you are at the end nearest the path of totality. Lower obscurities, perhaps down to 50% or so may even produce results.

Check out these links.

https://nationaleclipse.com/cities_partial.html

https://eclipse.gsfc.nasa.gov/SEpath/SEpath2001/SE2024Apr08Tpath.html

https://eclipse2024.org/eclipse_cities/statemap.html

Using my pattern mapping program which has extensive area search capability, I’ve compiled a list of all US and Canadian stations that fall within the 2024 Solar Eclipse path of ~100% totality. There are 456 stations. Results are drawn from the March 20 FCC LMS database and Industry Canada database. Sorry I don’t have Mexico available.

If you would like this list, download from this link. https://www.mediafire.com/file/125ih5yrmw4puib/2024-eclipse-stations-by-longitude.zip/file

Across the US and Canada, from its entry at Texas to its exit through NE Canada and into the Atlantic Ocean, the totality path width varies from a maximum of 199 km at US entry to about 160 km at the Atlantic exit off Newfoundland, or 123 to 99 miles. 456 stations are found in this eclipse path. I purposely set the path width to 210 km from start to finish. This gives a few km slop on both sides of the 100% totality path for good measure.

Unzip the downloaded .ZIP file, where you will find 3 files. The stations in each file are sorted by longitude, from west to east. This gives us the progression of the eclipse path, with the eclipse starting at the first station in the list and ending with the last station.

File #1 is a simple text file.

File #2 is in .CSV format. You can easily input it to an Excel file.

File #3 is in .HTML format. It includes links to each station’s Google Map latitude-longitude coordinates for the satellite view of the transmitter tower array.

Another link takes you to the FCC AM Query link for that station. I hope these files are beneficial. There should be many propagation path possibilities outside of this list as well.

(reprinted from the author’s blog at https://radio-timetraveller.blogspot.com/ )

********

Further sources of information concerning the eclipse include the following websites:

http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2024_GoogleMapFull.html?Lat=43.66400&Lng=-76.13690&Elv=88.0&Zoom=6&LC=1

(Clicking anywhere on this map page will give all the information you need about obscuration, length of eclipse etc.at a given location). Also:

https://www.greatamericaneclipse.com/april-8-2024

https://eclipsewise.com/2024/2024.html

Animations of the path of the eclipse versus time can be seen at:

https://eclipsewise.com/solar/SEanim400/2024_04_08_TSE_400px.gif

http://7dxr.com/4all/100km8Apr-movie–Frissell-HamSCI.mp4

The latter is particularly interesting, as it shows the moon’s shadow at 100km height above the earth, an area of special interest to DXers, as it is the lower edge of the E-region of the ionosphere. Note especially that as the eclipse ends over the North Atlantic Ocean, that there is a temporary darkness path between Europe and North America, because night will already have fallen in Europe. So will there be blips of TA DX in eastern North America as the eclipse passes by? Listen, and find out!

Finally, our DX could be of interest to ionospheric physicists also. The rapidly changing listening conditions will be indicating a similarly turbulent ionosphere, and DXers’ documenting those listening conditions through SDR recordings could provide information that will be useful to scientists who want to gain a better understanding of the Earth’s ionospheric dynamics.

HamSCI is an organization of volunteer citizen-scientists and professional researchers who study upper atmospheric and space physics, and will be interested in examining MW DXers’ wideband SDR recordings made during the eclipse period, and indeed, in having DXers assist with HamSCI’s research. (see https://hamsci.org/eclipse. Especially if you are an amateur radio operator, there are several other ways that you might also contribute to the project.)

(This first appeared in IRCA’s DX Monitor and is used with permission. See https://www.ircaonline.org/default.php for club details)

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Only One Week To Go: HamSCI Presents the Solar Eclipse QSO Party!

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Many thanks to SWLing Post contributor, Edward Efchak, who shares the following announcement:

ONE WEEK TO GO! SAVE THE DATE!!

Monday, April 8TH!!

HamSCI Presents the Solar Eclipse QSO Party – April 8, 2024

Join with thousands of your fellow amateurs as part of the largest crowd-sourced event for ham radio scientific exploration ever! The SEQP is part of The Festivals of Eclipse Ionospheric Science and is for learning more about how the ionosphere works. Use any mode, any band for all or part of the day! Participation can be from everywhere – you need not be near the path of the eclipse to contribute valuable data by participating.

Are you a contester? For details on the SEQP contest and rules go to www.hamsci.org/contest-info. Don’t forget to send in your log!
For the Gladstone Signal Spotting Challenge using CW, WSPR and FST4W modes go to www.hamsci.org/contest-info.
If you’re an SWL or AM DX’er, there is The Medium Wave Recording Event for you as well! Go to www.hamsci.org/mw-recordings/.

Or just get on the air and help provide the data to better understand the ionosphere.

Save the date – Monday, 8 April 2024

Get on the air! 1400-2400 UTC

Do it for science!! Any band/any mode (except the WARC bands)

HamSCI serves as a means for fostering collaboration between professional researchers and amateur radio operators. It assists in developing and maintaining standards and agreements between all people and organizations involved. Its goals are to advance scientific research and understanding through amateur radio activities and encourage the development of new technologies to support this research.

For more information about HamSCI, please visit the HamSCI website (www.hamsci.org) . For more information about the Festivals of Eclipse Ionospheric Science educational opportunities for the amateur community and the public please visit our information pages.

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2024 Eclipse: HamSCI Roundtable Events

The Solar Eclipse Is One Month Away!

Learn How You Can Participate in Two HamSCI Roundtable Events

The last total solar eclipse across North America for twenty years will occur on Monday, April 8th. Hams across North America are asked to participate in learning more about how the ionosphere functions by getting on the air to help scientists in a series of ionospheric experiments.

Connect with HamSCI members and curious hams on Wednesday, March 27 at 8PM (Eastern) / 5PM (Pacific)*, or that same day at 10PM (Eastern) / 7PM (Pacific)* for a Zoom presentation on HamSCI’s Festivals of Eclipse Ionospheric Science (FoEIS). The presenters will take your questions during the 30-minute presentations.

The link to these presentations is here: https://scranton.zoom.us/j/286316405?pwd=QWdwMlFPbDlYeXg5ZDg1dmYzeFdCUT09#success

The program will start by covering HamSCI’s basis and purpose, quickly moving into why we are conducting experiments, how hams and SWLS can participate, and what we hope to learn from the event. Along the way, we will discuss why the science behind the events is important to users of the high frequency radio spectrum – including amateur radio operators!

Learn about the HamSCI’s eclipse-focused operating events:

Solar Eclipse QSO Party (SEQP)

Gladstone Signal Spotting Challenge (GSSC)

Medium Wave Recording Event

Time Delay of Arrival (TDOA) Event

Grape 1 Doppler Receiver project

…and more!

There is no need to pre-register, create an account or log into any site. Simply follow this link at the date and times above to be taken to a Zoom meeting room, hosted by HamSCI: HamSCI FoEIS Roundtable Zoom Link

Join us on March 27th!! Get on the air April 8th!!

For more information about HamSCI, to join our mailing list, or participate in our work, please visit us at www.hamsci.org.

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HamSCI Reminder: Contribute to ionospheric research during the October 14, 2023 solar eclipse!

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Many thanks to SWling Post contributor, Nick Hall-Patch, who shares the following announcement:

How DXers can contribute to ionospheric research during the 14 October 2023 solar eclipse

There will be an annular solar eclipse on 14 October, 2023 when, at totality, the size of the Moon’s disk will appear slightly smaller than the size of the Sun’s disk. This eclipse will affect all of North America, as well as Central and part of South America, as seen in the map below.

AM Broadcast Band DXers know that the blocking out of radiation from the sun during a total solar eclipse can introduce temporary night time listening conditions over an area far beyond the path of totality.

The upcoming annular eclipse is expected to have a similar effect on daytime medium wave listening conditions as would a total solar eclipse, and should not be missed by DXers. Live listening can be done during the eclipse, as well as recording the entire medium wave band, using SDRs (software defined radios).

There might be more to our DXing results than new and unexpected receptions of distant radio stations, however. The rapidly changing listening conditions will be indicating a similarly turbulent ionosphere, and DXers’ documenting those listening conditions through SDR recordings could provide information that will be useful to scientists who want to gain a better understanding of the Earth’s ionospheric dynamics.

How can DXers contribute to ionospheric research?

HamSCI is an organization of volunteer citizen-scientists and professional researchers who study upper atmospheric and space physics, and will be interested in examining MW DXers’ wideband SDR recordings made during both eclipses, and indeed, in having DXers assist with HamSCI’s research. In fact, IRCA members contributed to HamSCI’s work about the 2017 total solar eclipse by contributing their DXing results: https://hamsci.org/sites/default/files/publications/2019_am-eclipse2017_hall-patch.pdf

HamSCI is still welcoming experienced medium wave DXers who are using good quality SDRs, especially in the southeastern USA and in Latin America. Please go to https://hamsci.org/mw-recordings/ and discover how to make sure that those DX files will also qualify as scientific data that can become part of the public record.

It will be important to have many participants in this project. To sign up, please go to https://hamsci.org/mw-recordings/ and discover how to make sure that those DX files will also qualify as scientific data that can become part of the public record.

Those interested in finding out about all the research that HamSCI will be doing during the upcoming eclipses, check out https://hamsci.org/eclipse . Especially if you are also an amateur radio operator, there are several other ways that you might contribute to the project.

But, even if you can’t contribute to scientific research, don’t forget to get out there and DX during the eclipse. You might be surprised at what you can hear.

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How DXers can contribute to ionospheric research during the October 14, 2023 solar eclipse!

How DXers can contribute to ionospheric research during the 14 October 2023 solar eclipse

How can DXers contribute to ionospheric research?

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Using Doppler Shift and Time Stations to Detect Solar Flares

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A WWV Time Code Generator (photo taken at WWV in Fort Collins, Colorado)

Many thanks to SWLing Post contributors, Troy Riedel and Jock Elliott, for sharing the following post from Spaceweather.com:

A NEW WAY TO DETECT SOLAR FLARES: Around the world, ham radio operators are experimenting with a new way to detect solar flares–the Doppler Shift method. Brian Curtis of Sault Ste Marie, Michigan, demonstrated the technique on June 20th when the sun produced a powerful X1.1-class solar flare:

Image by Brian Curtis

“I monitor the frequency and field strength of Canada’s CHU time station transmitting at 7850 KHz,” explains Curtis. “During the X-class flare event, I was able to detect the Doppler shift of the station’s carrier frequency (green plot). It shifted by 5 Hz, which is a small change, but very obvious!”

When radiation from a solar flare hits Earth’s atmosphere, it ionizes the air, temporarily boosting the thickness of our planet’s ionosphere. Any radio station skipping off the ionosphere will suddenly find its frequency Doppler shifted (because its reflection point is moving). Shortwave stations such as WWV, WWVH, and CHU transmit carriers with atomic-clock grade frequency stability, so they are perfect sources for Doppler monitoring.

Sudden changes in the ionosphere caused by flares or even sunrise/sunset can Doppler shift the frequency of stations like WWV. Image credit: Collins et al (2021) [Original image via HamSci and SpaceWeather.com]

“I have been monitoring radio stations for decades, noting sudden changes in signal strength as a means of monitoring space weather events,” says Curtis. “It is only fairly recently (~4 months) that I started to experiment with monitoring the Doppler shift of HF stations. The June 20th X-class flare event is by far the most dramatic that I have witnessed thus far.”

Would you like to detect solar flares this way? The HamSCI citizen science program has developed a Personal Space Weather Station specifically for Doppler shift measurements. This technique can also be used to study solar eclipses, earthquakes and tsunamis, and much more.

Click here to read the full story on Spaceweather.com, more on EOS.org and HamSCI.org.

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