Last month, I sent the message below concerning an increased level of
strong-signal 40M band sweeping at all hours of the day. At first, I
thought these sweeps were local given the extremely strong intensity
during all day-parts.
Several of you suggested that I investigate the possibility that these
sweeps are part of an "ionospheric chirping" project. After about a
month
of research, I have learned that these sweeps are being transmitted by
three transmission facilities as part of a complex Relocatable Over the
Horizon Radar System (ROTHR). Presumably, this system started out as a
joint DoD and U.S. Navy project, but has now morphed for purposes used by
the Department of Homeland Security for tracking illicit narcotics
activity between South America and the U.S.
As I indicated, three transmission facilities are used. They are (1)
Norfolk, VA; (2) Freer, TX; and (3) Vieques, Puerto Rico. See the links
below for more information on this project:
http://www.raytheon.com/products/stellent/groups/public/documents/legacy_site/cms01_049201.pdf
http://www.prnewswire.com/cgi-bin/micro_stories.pl?ACCT=149999&TICK=RTN&STORY=/www/story/01-11-2005/0002818279&EDATE=Jan+11,+2005
Here's what happening: These facilities are transmitting high power
sweeps through the HF spectrum at a rate of 100 kHz/sec., every 12
minutes
(exactly 5 times per hour). In Jacksonville, FL, the strongest station
heard sweeps through the CW portion of the 40M band at exactly :06, :18,
:30, :42, and :52 minutes past the hour. The second-strongest station
sweeps through CW portion of 40M at exactly :09, :21, :33, :45, and :57
minutes past the hour. The third station is rather weak here but
transmits following the other two but it is always at the 30 second
interval of the minute. In total, these sweeps are QRM-ing the band at
15
times per hour. You may have heard these sweeps and just ignored them as
someone trying to sweep the VSWR of their antenna systems. That is what
I initially thought.
I would like to ask that as many of you participate in a simple test and
listen at these times -- especially those of you in the Southeast U.S.,
to
record relative S meter readings of these sweeps and report back to me.
The sweeps occur relatively fast, but your S-meters will peak with a
strong signal just as if you are sweeping with a VFO. If you have a
transceiver with a bandscope, you will see these sweeps march across
display at the precise rate of 100 kHz per second. Please note the type
of antenna and height you are using in your reply.
According to my research, the only ionospheric chirping system that
transmits at 12 minute intervals is this one used by Homeland Security.
I
know the odds of asking them to notch and protect the 40M band is close
to
zero, but I would like some more data before I begin escalating an
attempt
with the proper authorities. Because this system is used for DoD, U.S.
Navy, and DHS purposes, they are exempt from FCC rules and general
identification requirements. So, tracking the source was not an easy
exercise.
I also just received a copy of a special HF chirping software package
that
together with a 1 PPS GPS, will allow me to precisely locate the distance
of these transmissions to better identify which station is producing the
strongest signal.
If you have some time this weekend, please listen for these sweeps at the
intervals listed above on 40M and get back to me with your results.
Thanks.
Paul, W9AC
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Not exactly related to TT, but since so many TT users operate on 40M,
I'll
throw this out...
I have been noticing an alarming amount of band sweep activity lately.
It
occurs where someone keys their transmitter and quickly sweeps the band
from
7.0 - 7.3 MHz. I see this activity all day long on 40M and it appears to
come from multiple sources.
As best as I can tell, folks are trying to sweep their antenna systems,
but
this is occurring at least once every 5-10 minutes. The rate of sweep is
constant, so it may be that a common piece of software or test gear is
responsible? I'm not sure what these people are trying to accomplish
with
these repetitive sweeps all day long.
Anyone else notice this behavior, especially on 40M lately?
Paul W9AC
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