List, not sure if this applies to the noise on the
repeater or not but Newline has confirmed a
snap-crack-pop noise.

ON THE AIR:  THE NEW AMERICAN UHF WOODPECKER

Is the US. Military interfering with your UHF repeater
system?  Could be, if 
you live in the great American South-West.  Take a
listen:

---

UHF WOODPECKER NOISE HERE

--

And that noise could be coming to a repeater near you.
 Amateur Radio 
Newsline's technical specialist Nate Duehr, WY0X, is
in Denver, Colorado, with 
more:

--
For two years, ham radio operators of UHF repeater
systems in the Colorado 
Front Range have been hearing a regular pulsing or
clicking  noise on weak 
signal repeater users.  The interfering signal has a
rhythmic clicking sound, 
similar to a slow motor vehicle ignition spark  or as
some hams have nicknamed 
it, "The woodpecker".  Almost every UHF repeater
system in the Denver area has 
experienced this noise.

In November of 2002, several hams volunteered to help
the Colorado Council of 
Amateur Radio Clubs find the source of the noise via
radio direction-finding 
techniques.  The offending transmitter was
surprisingly found to be located on 
Buckley Air Force Base, just east of  Denver.

At first, the hams assumed the system was likely to be
a malfunctioning 
transmitter, and various attempts at contacting the
proper authorities were 
made.  For a short time, the system was even switched
off from time to time, 
presumably when not in use.

As more information was gathered, hams learned from
various sources including 
the Internet, that the system causing the harmful
interference is a military 
radio system known as the Enhanced Position Location
Reporting System, or 
EPLRS.

EPLRS and its airborne counterpart, AEPLRS are spread
spectrum systems 
designed such that they have multiple UHF channels
that overlap.  These 
channels are numerous enough that they cover virtually
the entire weak-signal 
and repeater input portions of the UHF Amateur band in
Colorado, from 
approximately 426 MHz to 450 MHz.  Spectrum analysis
data captured by local 
hams and the FCC confirms this.

How does this affect you?

Recently, Colorado hams have been hearing from our
neighbors in Albuquerque, 
New Mexico that they are hearing similar interference
on UHF repeaters in the 
Sandia Peak area, and at least one source indicates
that hams may also have 
reported similar interference to the FCC in
Sacramento, California.  
Furthermore, other research indicates that it is
likely that more than 25 
EPLRS systems are slated for deployment or are already
deployed in the 
Continental United States, Alaska and Hawaii.

Hams who enjoy UHF weak signal and FM repeater
operation near military 
installations should be alert to the possibility of
such interference.  It is 
hoped that more widespread knowledge of this very
broadband UHF interference 
source may help hams in other areas who have been
hearing it.

For further information, a public e-mail discussion
group has been set up that 
anyone can join by sending an e-mail to
[EMAIL PROTECTED] . 

Reporting from Denver, for Amateur Radio Newsline,
this is Nate Duehr, WY0X.

--- Kevin Custer <[EMAIL PROTECTED]> wrote:

> Rick Stoneking wrote:
> 
> > All,
> >  
> > I am trying to resolve a problem on a local
> repeater where they are 
> > having intermittent 'noise' problems. 
> >  
> > The noise may be related to weather (wet or cold
> causing an increase 
> > in the problem) though it is not a everytime
> event. 
> >  It was originaly believed that it was a grounding
> problem but 
> > grounding improvements have had no lasting effect.
> >  At one point it was said that the guy wires were
> causing the problem 
> > so the club recently put insulators in all 9 guy
> wires about 6 to 8 
> > feet from the anchor point - no help.
> >  The problem, which sounds like static or popping,
> occurs only during 
> > transmitting incoming audio.  In other words, all
> controller generated 
> > audio is fine, no noise what so ever.
> 
> 
> Some reference:
>
http://www.repeater-builder.com/antenna/cracking.html
> http://www.repeater-builder.com/antenna/static.html
> 
> Kevin Custer  W3KKC
> 



                
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