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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