DOI: 10.5281/zenodo.2555203
title: Solar Eclipse 2017 recordings of medium-wave AM broadcast band from near Upsala, MN, U.S.A.

description: recorded by Mark Durenberger

location recorded:   45°49'38.98"N  94°37'47.97"W  

These data files are recordings of the entire medium wave broadcast band (535-1705kHz) from 16:57:22UT to 18:44:47UT from near Upsala, MN, U.S.A.   Data files are .wav format, but the archived files are .zip, with two .wav files packaged together in each .zip file.

Antenna:   1) from 16:57:22UTC until 17:53:05UTC:  broadband delta loop antenna, 22-foot apex with a 40-foot base, oriented 260-80 degrees until 17:29UTC, then oriented to 210-30 degrees;  using Wellbrook (https://www.wellbrook.uk.com/loopantennas/) ALA100 preamplifier

2)from  17:53:56UT until 18:44:47UT:     DKaz antenna (described at http://www.durenberger.com/documents/DKAZ070314.pdf), using DXEngineering RPA-1 preamplifier between antenna and receiver (https://www.dxengineering.com/parts/dxe-rpa-1), oriented 150-330 degrees

Receiver:  Microtelecom Perseus SDR (http://microtelecom.it/perseus/) with 10dB front end attenuation, center frequency set at 925kHz, recording 1600kHz wide passband, using Perseus software (http://microtelecom.it/perseus/software.html)
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 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.   During the solar eclipse of 21 August 2017, signals were observed changing from daytime to nighttime mode and then back again as the moon's shadow moved across the continental USA.

      The radio stations in this band use amplitude modulation, which requires a strong stable carrier wave, well suited for observing changes in signal strength over a time period.   The solar eclipse time period coincided with a group of 

thunderstorms near this location, so the files are heavily corrupted with a large amount of static crashes, interfering with weaker signals.

     Included in these files is one provided by Microtelecom ("perseusv5demo.exe") for playback of the .wav files, plus a help file, "PerseusV5QuickTuningGuide.pdf".  As well, there is a reference file to assist in identifying signals ("canusa-Jan2019.pdf").   Finally, there is set of instructions for using the software, along with instructions for using "Perseusv5demo.exe" to extract a time series of signal power for an individual radio station's signal ("Using Perseusv5demo to create signal strength time series-MD.pdf").
Finally, referencing the article archived at http://hamsci.org/sites/default/files/publications/2019_am-eclipse2017_hall-patch.pdf , will give the user of these files an idea of how radio reception datasets from different locations can be used to compare the effects that the solar eclipse had on radio propagation.