ARLA/CLUSTER: Contactos em 9 kHz (8971 Hz) na banda de VLF através do Atlantico

[João Costa > CT1FBF]

 Radio ham’s 9 kHz VLF signal crosses Atlantic

The ARRL report that a signal on 8,971 kHz has spanned the Atlantic,
from North Carolina to the UK

Running on the order of 150 µW effective radiated power, very low
frequency (VLF) experimenter Dex McIntyre, W4DEX, transmitted signals
on June 2 and 3 that were detected by Paul Nicholson, an SWL in the
UK.

Earlier this year, Nicholson detected McIntyre's WH2XBA/4 Experimental
Service VLF signal on 29,501 kHz. McIntyre needed no FCC license to
transmit on 8,971 kHz, since the Commission has not designated any
allocations below 9 kHz — dubbed “the Dreamers’ Band.”

“I’ll probably make more transmissions on 8.9 kHz when there is no
chance of thunderstorms,” McIntyre told ARRL this week. “Then, maybe
sliding down in frequency to see how low I can go for Paul to detect
the signal.”

Nicholson used sophisticated digital signal processing (DSP) software
to detect McIntyre’s transmission. The distance was approximately 6194
km (approximately 3840 mi). Nicholson was able to detect the VLF
signal during both daylight and nighttime paths.

On June 1 and into June 2, McIntyre transmitted a steady, GPS-locked
carrier at 8.971.000 kHz. Between 0000 and 0600 UTC, Nicholson
measured a carrier at that frequency in Todmorden, UK. He combined the
electrical and magnetic field receiver outputs to produce a
unidirectional antenna response.

“This brought the signal up to a significant level,” Nicholson
reported. “The signal bearing was roughly west. W4DEX is bearing 285°
from here. The S/N is max on a bearing of 315°, which puts the
prevailing southwesterly background nearer to the side of the antenna
response. This gave the signal a respectable 12.5 dB S/N in a 46 µHz
bandwidth.” Nicholson said McIntyre’s carrier also was visible during
a daylight path in a 23 µHz bandwidth.

Read the full ARRL story at
http://www.arrl.org/news/
radio-amateur-s-sub-9-khz-vlf-signal-detected-across-the-atlantic

Sub 9 kHz Yahoo Group
https://groups.yahoo.com/group/sub9khz/