DOI: 10.5281/zenodo.14176246
title: Annular Solar Eclipse 2023: recordings of the entire medium-wave AM broadcast band from Lockhart, TX, USA, Part 1

description: Files recorded by Mark Whittington, AG5RT

Grid square of location recorded:  EL19ET 

Maximum obscuration of the sun was 89% at 1654UT.  

These data files are recordings of the entire medium wave broadcast band (535-1705kHz) made during the annular solar eclipse of 14 October 2024 from 1524-1833UT from near Austin, TX, USA.  They are part of a set of such recordings made from 13 Oct 2135UT to 14 Oct 2138UT. 

Data Quality:   many spurious carriers, most very weak, so may not affect overall quality

Data files are .wav format, but the archived files are .zip, with two .wav files packaged together in each .zip file, using the prefix "AG5RT-wideband_15_2015kHz”.  As the total files recorded during the solar eclipse exceeded the Zenodo 50GB limit, the remainder of the dataset is found in "Annular Solar Eclipse 2023: recordings of the entire medium-wave AM broadcast band from Lockhart, TX, USA, Part 2”.

The recordings not included here or in Part  2 are available to provide reference data for the eclipse recordings.  Please contact HamSCI at am-eclipse@hamsci.org if you require this data. 

Antenna:  40' vertical

Receiver:   RSPduo, with SDRuno software, using center frequency 1015kHz, recording a 2000kHz wide passband.     "IF AGC" was unchecked; IF gain was set at 0 dB.   The RF gain control was set one click below where the OVERLOAD indicator would flicker.   The receiver was not locked to a frequency standard.  Computer time accuracy was determined by Meinberg NTP.

 

 
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 annular solar eclipse of 14 October 2023, 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 :

“AM Stations within Umbra 2023 Annular Eclipse.xlsx “, courtesy of Richard Cook KE6EE. 

"US-Canada AMBC List Nov_2023.xlsx", courtesy of Tim Tromp KE8JFM (https://amdxer.com/ambc/ )

“RDMW-2022-v1.2.2.zip”, 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/ )

 

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 zipped in “AG5RT-CarrierSleuth-Oct13-14.zip”, which will provide waterfall visualizations of all carriers for each AM broadcast band 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 .