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My report is late because I remotely recorded the transmissions at my Cohoe Radio Observatory and then had to retrieve the data. Due to winter driving conditions I could not retrieve the recorded I-Q data until 3 January 2023. I finally was able to analyze the recordings today, 16 January 2023. Cohoe Radio Observatory is about 125 km southwest of Anchorage as the crow flies but a 3.5 hour drive through the mountains.
I noted that tuning started at 1545:10 UTC for about 1 minute and then actual messaging commenced until a few seconds before 1600 UTC. The official message started at 1600:00 and lasted until just before 1610 UTC.
Reception was generally weak but obvious. The received signal level was fairly constant during the entire transmissions between 1545 and 1610 UTC.
I was using a square loop antenna oriented north-south. It is described here: https://reeve.com/Documents/Articles%20Papers/Reeve_SquareLoopAntenna1.2m.pdf and here: https://reeve.com/Documents/Articles%20Papers/Reeve_CohoeVLFLoopAntenna.pdf
I used the SDRPlay SDRduo receiver with the SDRuno software scheduled I-Q recording feature. The receiver sampling rate was set to 2 MHz with decimation set to 32, giving a 62.5 kHz recording bandwidth.
Additional VLF/LF articles are here: https://reeve.com/RadioScience/Radio%20Astronomy%20Publications/Articles_Papers.htm#Very_Low_Frequency_Applications
Whitham D. Reeve
Anchorage, Alaska USA