DOI: 10.5281/zenodo.14188531
title: Annular Solar Eclipse 2023: recordings of the entire medium-wave AM broadcast band from Victoria, BC, Canada, Part 1

description: recorded by Nick Hall-Patch, VE7DXR

Grid square of location recorded:  CN88ik

Maximum obscuration of the sun was 79% at 1620UT 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 1507UT to 1739UT from Victoria, BC, Canada.  They are part of a set of such recordings made from 13 October 1230UT to 15 October 1730UT             

Data Quality:  There is a gap in the recorded data 14 October from 1624 to 1638UT.  (Another SDR using a co-located antenna with a similar directional pattern was recording through that time period.  That data can be referenced at “Annular Solar Eclipse 2023: recordings of the entire medium-wave AM broadcast band from Victoria, BC, Canada, Part 3”.)    There was local electrical noise around 1675kHz and drifting during eclipse period, likely at other times as well.  There were CFAX-1070 spurious carriers found on these channels:   530, 540, 1410, 1480 1510, 1540, 1590, 1620, 1670 and 1700 kHz.  

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 "VE7DXR-Victoria-SmallLoop-wideband_454_1787kHz_ ".  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 Victoria, BC, Canada, Part 2” and “Annular Solar Eclipse 2023: recordings of the entire medium-wave AM broadcast band from Victoria, BC, Canada, Part 3”.

The recordings not included here or in Parts 2 or 3 are available to provide reference data for the eclipse recordings.  Please contact HamSCI at am-eclipse@hamsci.org if you require this data. 

Antenna:  1.4m square copper pipe loop, oriented north-south; ALA1530LN amplifier, serial number 1960 

Receiver:  RFSpace SDR-IP, 0dB front end attenuation, with a notch filter in the antenna feed line providing ~25dB attenuation at 1070kHz (local broadcaster's frequency). IQ files with a center frequency of 1120kHz, with 1333kHz wide passband, were recorded using SpectraVue v3.39 software.  The SDR-IP was locked to 10MHz provided by a Trimble Thunderbolt GPS Disciplined Clock .   Computer time accuracy was determined by Windows NTP server.

 
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/ )

“Eclipse2023LoggingsVictoria-NHP.pdf” provides a list of all AM radio stations and carriers logged during the eclipse, including information about the spurious carriers observed.

 

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 “VE7DXRVictoria-CarrierSleuth-Oct13-15.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 .