DOI: 10.5281/zenodo.15504888
title: Effects of the 2024 total solar eclipse upon reception of trans-Atlantic signals in the medium-wave broadcast band, using software defined radio files recorded in Sfax, Tunisia.

description: Recorded by:  Ashraf Chaabane, 3V9A.

Grid square of location recorded:  JM54iq

Maximum obscuration of the sun was 0%, as the eclipse ended in the North Atlantic Ocean, west of the recording site.  However, unusual signals were noted from North America during the eclipse period.

These data files are recordings of the entire medium wave broadcast band (535-1705kHz) made during the total solar eclipse of 8 April 2024 from 1915 to 2055UT from Sfax, Tunisia.   They are part of a set of such recordings made from 1814UT on April 8th, 2024 to 005UT on April 9th, 2024 and 1814UT on April 9th, 2024 to 0005UT on April 10th, 2024.

Data Quality:  Only limitation is a bit of thunderstorm static, otherwise good.

Data files are .wav format, but the archived files are .zip, with three or four .wav files packaged together in each .zip file, using the prefix “3V9A-wideband_305_1905kHz_ “.  

The recordings not included here are available by contacting HamSCI at am-eclipse@hamsci.org, if you require this data. 

Antenna:  100m wire at 320degrees, no termination.

Receiver:    Perseus, 0dB front end attenuation, with center frequency 1105kHz, recording a 1600kHz wide passband, using Jaguar Pro software.    Hardware was not locked to a frequency standard; Bodnar GPS locked frequency standard at 1705kHz was used as reference for Jaguar.

Recording computer time was set by Windows network time.
description: In the AM broadcast band (535-1705kHz), there are roughly two modes of broadcast station signal coverage, one of which occurs in the daytime, and the other at night. During the day time, signals are propagated by ground wave and not usually heard well beyond 150km from the transmitter. However, at night, an absorptive region in the ionosphere, the D-layer, disappears, allowing signals to refract off higher regions of the ionosphere, and to be heard hundreds and even thousands, of kilometers away from the transmitter. 

The radio stations in this band use amplitude modulation, which requires a strong stable carrier wave, well suited for observing changes in signal characteristics over a time period. During the total solar eclipse of 8 April 2024, signals were observed changing from daytime to nighttime mode, and then back again as the moon's shadow moved across North America. 

Included in these files is an installation file for the SDR control and playback software, SDR Console (“SDR-Radio V3.3, 64-bit, 2024-02-05_0741.exe”), to allow a first examination of the .wav files; this is courtesy of Simon Brown, G4ELI, its developer.  The latest version is available at https://www.sdr-radio.com/Console .  Instructions for playing back SDR .wav files in SDR Console for the first-time user are found in “OpeningSDRfilesInConsole.pdf” on this site.

There are also reference files to assist in identifying signals heard :

"AMBC Raw List April_2024.xlsx", for individual broadcaster call letters etc., including transmitter geographical co-ordinates, courtesy of Tim Tromp KE8JFM (https://amdxer.com/ambc/ )

“RDMW-2022-v1.2.2.zip”, for maps of broadcaster locations and transmitter patterns, courtesy of William Scott, WE7W ( https://radio-timetraveller.blogspot.com/ )

"2023-24_IRCA_Mexican_Log.pdf”, courtesy of International Radio Club of America (https://www.ircaonline.org/ )

"IRCA Slogans - March 22, 2024.pdf" for identifying slogans used by radio stations,  courtesy of International Radio Club of America (https://www.ircaonline.org/ )

"20240409-EuropeAfricaMEListing.pdf" lists all medium wave and longwave broadcasters on the air on 9 April 2024 in Europe, Africa and the Middle East, with transmitter co-ordinates and other information, courtesy of Günter Lorenz, DL3GLF, and MWList.org 

"Exact frequencies of medium wave broadcasters.pdf" is a snapshot of a database of fine scale measurement of the frequencies of MW stations worldwide that were current as of April 9, 2024, the day after the total solar eclipse.  They are also courtesy of Günter Lorenz, DL3GLF, and MWList.org  

"Offsets on Medium Wave – some Notes and Examples.pdf" provides further background about measurement of the frequencies of received signals and is courtesy of Nils Schiffhauer, DK8OK 

 

Finally, a copy of Carrier Sleuth software (“CarrierSleuthWindowsMay2024.zip”) is included, courtesy of its developer, Chris Smolinski, W3HFU, along with further instructions for use (“CarrierSleuthOverview.pdf” ).   This can be used to view .fft files compressed in “3V9A-CarrierSleuth-Apr08-09.zip” which will provide waterfall visualizations of all carriers for each AM broadcast band 10kHz channel during the entire recording period.    Carrier Sleuth may also be used to create new .fft files from the data.  The latest version is available at https://www.blackcatsystems.com/software/medium_wave_carrier_display_app.html .

 

(If this data is used for research, cited in an article, paper, poster or presentation, the participants would expect and appreciate the courtesy of receiving credit for their work.  Questions regarding attribution should be directed to HamSCI, at hamsci@hamsci.org .)