DOI: 10.5281/zenodo.14174067
title: Annular Solar Eclipse 2023: recordings of the entire medium-wave AM broadcast band from Phoenix, AZ, USA, Part 1

description: recorded by Burke Baumann, KF7NP

Grid square of location recorded:   DM33wp

Maximum obscuration of the sun was 79% at 1632UT 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 1501UT to 1755UT at Phoenix, AZ, USA.  They are part of a set of such recordings made from 1304 to 2200UT on 14 October and from 1300 to 2200UT on 15 October, 2023.

Data Quality:   Some broadband local electrical noise was present, plus some spurious carriers, but did not affect overall quality.

Data files are .wav format, but the archived files are .zip, with four or five .wav files packaged together in each .zip file, using the prefix "KF7NP-wideband_160_2080kHz".  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 Phoenix, AZ, 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:  Hustler 20m mobile vertical with an inline choke balun in the feed line   

Receiver:  Receiver used:    ICOM IC-7610 SDR transceiver (16-bit data), 0dB front end gain / attenuation.  (Baumann: I also believe the IC-7610 has a low pass filter with a cutoff at 1.6 MHz so signals above this may be attenuated.)  Center frequency was 1100kHz, recording a 1920kHz wide passband using HDSDR software.   The receiver was locked to a 10 MHz signal from a homebrew GPSDO reference, which was always accurate to better than  0.1 ppb.  Computer time accuracy was determined by Dimension 4 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 “KF7NP-CarrierSleuth-Oct14-16.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 .