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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" <[email protected]> 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 <[email protected]> > 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/> > > > > -- > > WISPA Wireless List: [email protected] > > > > Subscribe/Unsubscribe: > > http://lists.wispa.org/mailman/listinfo/wireless > > > > Archives: http://lists.wispa.org/pipermail/wireless/ > ------- End of Original Message ------- > > > -- > No virus found in this incoming message. > Checked by AVG Anti-Virus. > Version: 7.0.344 / Virus Database: 267.11.9/116 - Release Date: 9/30/2005 > > > > -- > No virus found in this outgoing message. > Checked by AVG Anti-Virus. > Version: 7.0.344 / Virus Database: 267.11.9/116 - Release Date: 9/30/2005 > ------- End of Original Message ------- |
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