DOI: 10.5281/zenodo.14172100
title: Annular Solar Eclipse 2023: recordings of the entire medium-wave AM broadcast band from near Medicine Hat, AB, Canada, Part 1

description: recorded by Nigel Pimblett, VE6TNF

Grid square of location recorded:  DN49rx

Maximum obscuration of the sun was 59% at 1629UT on 14 October 2023.  

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 1516 to 1752UT from near Medicine Hat, AB, Canada.   They are part of a set of such recordings made from 14 October,  1358UT to 1800UT. 

Data Quality:   Good; crisp sounding demodulation is possible using SDR Console.   

Data files are .wav format, but the archived files are .zip, with about ten .wav files packaged together in each .zip file, using the prefix " VE6TNF-wideband_120_2120kHz_”.  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 near Medicine Hat, AB, Canada, Part 2”.

The recordings not included here or in Part 2 are available by contacting HamSCI at am-eclipse@hamsci.org if you require this data. 

Antenna:  Wellbrook Phased Array.  East-west loops are 20m perimeter deltas, 40m separation with the bottom wire about 30 cm above ground. Amplifiers are Wellbrook ALA100M.

 

Receiver:      RX888, with center frequency 4500kHz, recording 8000kHz wide passband, using SDR Console.  Raw data was a single RF64 WAV file.  That file was re-sampled using SDR Console to deliver multiple WAV files of 2000kHz passband with a center frequency of 1120kHz, so that they could both be stored in Zenodo and processed more easily.   The original file can be obtained by contacting HamSCI at am-eclipse@hamsci.org .

Although the RX888 was not frequency locked, the receiver had been powered up for a good 24 hours prior to the recording.  Computer time had been 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 “VE6TNF-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 .