Possibly, but why did it become a problem when I replaced the antenna?

Scott Reed
Owner
NewWays
Wireless Networking
Network Design, Installation and Administration
www.nwwnet.net

---------- Original Message -----------
From: "Rick Smith" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org>
Sent: Tue, 4 Oct 2005 08:30:48 -0400
Subject: RE: [WISPA] TV Interference

> use shielded ethernet cable.  that's the problem.
>
>
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Scott Reed
> Sent: Tuesday, October 04, 2005 7:53 AM
> To: WISPA General List
> Subject: Re: [WISPA] TV Interference
>

>
> Thanks John,
> and Duh.  The ferrite beads are in the truck, but not in the mind.  Would have been easy.
>
> Not an integral antenna, problems started when we changed antenna.  Our antenna is about 15' below the TV antenna, about 5' above where the TV coax enters the house.
>
> The radio is an early Deliberant 1300, plastic baseplate, no ground lug.  If the beads don't do it, I will probably change out the radio.
>
> Scott Reed
> Owner
> NewWays
> Wireless Networking
> Network Design, Installation and Administration
> www.nwwnet.net
>
> ---------- Original Message -----------
> From: John Scrivner <[EMAIL PROTECTED]>
> To: WISPA General List <wireless@wispa.org>
> Sent: Mon, 03 Oct 2005 22:39:40 -0500
> Subject: Re: [WISPA] TV Interference
>
> > RF Interference was my job for some time in my old CATV days. Here are
> > some tips. First, is this an integrated radio/antenna? If it is then you
> > may have RF interference traveling along the Cat 5 cable. If so then
> > snap a ferrite bead onto the cat 5 cable near the antenna and POE ends
> > of the cable run. This may fix the trouble. RF ferrite beads are good to
> > keep around whether they fix this particular problem or not.
> >
> > Channels 2 thru 5 are much more susceptible to electrical interference
> > than higher VHF channels. There is actually quite a bit of band space
> > between channel 6 and 7. Cable channels 14 through 22 and 98 and 99 are
> > actually between channels 6 and 7 when incrementing by frequency up the
> > band. I know that seems weird but it is true. This could explain why 2
> > thru 6 are more affected than channel 7 in your situation. Power
> > supplies are often the source of electrical interference. If you have a
> > second radio and/or supply to try then I would do this. Also you may
> > consider a ferrite bead on the output side of the power supply for your
> > radio. It could be the noise source. You have probably all seen the
> > cylinders inline with the outputs of commonly used wall wart power
> > supplies. These are ferrite beads integrated into the outputs of the
> > supplies for just this reason.
> >
> > Vertical separation is important in any RF environment. You may not need
> > 10 feet of separation but you may need at least a few feet of separation
> > between your TV antenna and you WISP antenna. RF signals (even from far
> > removed bands) can "swamp" receivers in other bands and cause a myriad
> > of problems, not the least of which could be the trouble you describe.
> >
> > One unlikely cause could be out of band interference where your wireless
> > radio could be actually radiating RF into the lower VHF channel bands
> > directly (which is not a common problem). It is easy to correct though.
> > It just requires the replacement of the bad radio. This may be a good
> > thing to try first as changing the radio is easy and isolates two
> > possible problems (power supply noise and out of band emissions)
> > Obviously you would want to change the wall wart power supply also if
> > the trouble does not go away with changing the radio.
> >
> > I have rarely seen grounding as a problem producing similar issues. I
> > have seen a proper ground either missing and leading to ground loops and
> > RF noise and I have seen the reverse where a ground of any kind caused
> > the interference. This is a really bizarre situation but it does happen.
> > I have usually found the grounding issue to be related to poor grounding
> > of the electrical service and/or tower. I once had a mobile home where
> > my CATV ground was carrying all unbalanced loads for all electrical
> > circuits for the entire home. When I unhooked it the ground lug sparked
> > and I received a shock. Needless to say I had the owner call an
> > electrician immediately. In this particular situation the cable
> > television drop line had a melted outer jacket from all the current
> > being carried by the outer cable sheath. I thought it had received a
> > lightning strike but it was actually just caused by too much current
> > through the cable line's shield. For those of you who do not know what
> > neutral or ground currents are in power electricity you may want to do a
> > little reading. Scary stuff!
> >
> > Order yourself some ferrite beads to keep on hand if you do not have any
> > now. Your local two way radio shop will have them if you need some
> > quick. Please do us all a favor and share what you had to do to make
> > this all work once you find a solution.
> > All the best,
> > Scriv
> >
> > Scott Reed wrote:
> >
> > > OK, I have dealt with TV interference before, but this one has me
> > > stumped.  Installed customer 4 weeks ago.  All is fine.   Over last
> > > week, signal strenght started degrading.  Customer complained about
> > > speed slowdown.   Customer was out of town for weekend but we went out
> > > Saturday and RSSI was really bad.  Did some testing.  Replaced 15dB
> > > antenna with a 19.  Raised about 4".  Signal strength improved
> > > dramatically.  Customer came home Sunday and there were dots/lines in
> > > channels 2 and 5.  Channel 7 works fine.  The 2 & 7 transmitters are
> > > not far from each other.  Unplugged radio and dots/lines went away.  
> > > Plugged it back in, dots/lines.  So, why only channels below 7 and why
> > > only with the new antenna?
> > >
> > > Scott Reed
> > > Owner
> > > NewWays
> > > Wireless Networking
> > > Network Design, Installation and Administration
> > > www.nwwnet.net <http://www.nwwnet.net/>
> >
> > --
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> ------- End of Original Message -------
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