{"id":62175,"date":"2025-02-24T07:57:20","date_gmt":"2025-02-24T11:57:20","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=62175"},"modified":"2025-02-24T12:01:35","modified_gmt":"2025-02-24T16:01:35","slug":"beyond-dxing-analyzing-medium-wave-propagation-during-the-2023-annular-eclipse","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2025\/02\/beyond-dxing-analyzing-medium-wave-propagation-during-the-2023-annular-eclipse\/","title":{"rendered":"Beyond DXing: Analyzing Medium Wave Propagation During the 2023 Annular Eclipse"},"content":{"rendered":"

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.\u00a0 The article ends by asking assistance from DXers to help ID enhanced signals in the 2023 eclipse data sets.\u00a0\u00a0<\/strong><\/em><\/p>\n

Medium Wave Monitoring During the 2023 Annular Solar Eclipse\u2014Not Just About DXing<\/b><\/h1>\n

By Nick Hall-Patch, VE7DXR<\/b><\/p>\n

Background<\/b> \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/b><\/h1>\n

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.\u00a0 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\u2019s 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.<\/p>\n

That study of KSL\u2019s 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\u00a0 http:\/\/dxer.ca\/images\/stories\/2019\/irca-reprint-index.pdf<\/b><\/a>) which proved to be of interest to HamSCI<\/b><\/a>, an amateur radio citizen science group that had already been using amateur radio communications as a way to study that eclipse\u2019s effects upon the ionosphere. A version of the article appeared on HamSCI\u2019s website<\/b><\/a> and the SDR files referenced by the article were also hosted by the HamSCI community on zenodo.org<\/b><\/a>, along with SDR data from three further locations in eastern America. (Go to zenodo.org<\/b><\/a>, and search on the phrase “Solar Eclipse 2017 recordings” to examine this data for yourself.) \u00a0 Zenodo is a long-term open repository for scholarly work, and these data sets have since been downloaded hundreds of times.<\/p>\n

Why would these 2017 SDR files have been of interest to an organization studying radio wave propagation?\u00a0 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.\u00a0 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. \u00a0 During a solar eclipse, the brief period of darkness along the path of the eclipse can allow AM broadcasters\u2019 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.<\/p>\n

Preparation for the 2023 Solar Eclipse<\/b><\/h1>\n

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.\u00a0 From the standpoint of a scientist, this was \u201cfound data\u201d requiring judicious handling and compensation.\u00a0 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.<\/p>\n

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.\u00a0 In other words, participating DXers would be asked to think a bit more like scientists for the duration of the recordings.\u00a0 Making recorded IQ files of optimum use to propagation researchers would include the following:<\/p>\n