VLF NPM 21.4 kHz with IQ video

WA9ONY

https://youtube.com/shorts/GQ_5fr2_UNM?si=pIIZpBno8au6agA2

NPM is a USA Navy VLF transmitter that operates on 21.4 kHz. It's located in Lualualei, Hawaii.

21° 25' 22" N  158° 9' 1" W

The station's current antenna was built in 1972 and consists of two guyed masts, each 458.11 meters (1503 feet) tall. The masts are configured as umbrella antennas.

Lualualei VLF transmitter

https://en.wikipedia.org/wiki/Lualualei_VLF_transmitter

https://www.sigidwiki.com/wiki/NPM

NPM is over 2,400 miles from my QTH: Camas, WA USA

KiwiSDR antenna is 39" dia. loop (49 turns of 22 AWG Magnet Wire) up 10'

73 David WA9ONY

jks

Hi David. Very nice. VLF/LF signals are a particular interest of mine.

For a different kind of image set draw/mode/PLL to density/carrier/off. And use GPS correction of the ADC clock, or careful manual calibration against WWV 15 or 20 MHz.

You should be able to get a very stable 4-quadrant IQ pattern that looks nice and shouldn't drift much.

More info:

https://forum.kiwisdr.com/index.php?p=/discussion/1333/external-gps-clock-frequency-suggestion