[TenTec] 40M Band Sweeps (Request)

Sat Jan 12 13:57:44 EST 2008

Paul: That's fascinating information!  Thanks for your time to research that 
and bring it to our attention.

I would suspect that if enough fuss was raised they could notch the system 
and still have the performance they need, but I doubt that anyone would 
consider a 20 millisecond burst every four minutes to fit the FCC's 
definition of harmful interference.  Most cell phone calls have more 
glitches that that.  It could actually be beneficial if for no other reason 
it blows chunks of garbage into the Chinese OTHR that bugs everybody on 40 
meters in the mornings.  It's even possible that this system has a 'secret 
mode' that is capable of jamming the Chinese system if ever needed.

Wouldn't you just love to use that antenna system in a contest!

         Ron  N6IE
      www.N6IE.com

----- Original Message ----- 
From: "Paul Christensen" <w9ac at arrl.net>
To: <tentec at contesting.com>
Sent: Saturday, January 12, 2008 7:30 AM
Subject: [TenTec] 40M Band Sweeps (Request)

> 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
>
> ---------------------------------------------------------------------------------------------------------------------------------------
> 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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