DOI: 10.5281/zenodo.14183381
title: Annular Solar Eclipse 2023: recordings of the entire medium-wave AM broadcast band from near Austin, TX, USA

description: Files recorded by James Niven

Grid square of location recorded:  EM10fc

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 1540 to 1749UT from near Austin, TX, USA. 

Data Quality:  There is a short gap in the recording after the file ends at 1700UT, and then over the next half hour, the Perseus drifts down by the better part of a Hertz, then appears to stabilize again.  It looked quite stable before 1700UT.

Data files are .wav format, but the archived files are .zip, with two or three .wav files packaged together in each .zip file, using the prefix "JNiven-wideband_90_2090kHz“. 

 

Antenna:  east facing DKaz antenna, 900 ohm termination, no amplifier at antenna



 Receiver: Perseus using 0dB  front end attenuation. with center frequency 1090kHz, recording a 2000kHz wide passband, using Jaguar Pro software.  The receiver was not frequency locked but includes a reference frequency of 1080.0002kHz from KRLD in Dallas, TX.      Computer time was set manually.
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 “Niven-CarrierSleuth-Oct14.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 .