Do you have the shielded cable? Mark
++++++++++++++++++++++++++++++++ <insert witty tagline here> ----- Original Message ----- From: "Marlon K. Schafer" <[email protected]> To: "WISPA General List" <[email protected]> Cc: <[email protected]> Sent: Wednesday, January 07, 2009 7:47 AM Subject: [WISPA] FM radio station site strangeness > Hi All, > > I think we finally have this all figured out. Now I just have to figure > out > how to fix it. > > We've been up there for over 6 years now. It's certainly been a > problematic > site though. Constant channel changes (we have 3 competitors a mile away > and pick up hundreds of ap's from in town) are the norm. > > This fall (a month or two ago) one of the tenants left the building. This > cleared out most of the hardware that was in there. A little bit before > that I replaced an Inscape Data and a smartBridges combo with a single MT > access point, using one of the cables that had been working for one of the > other two. > > About a week ago things started to really act up. Multiple devices were > having trouble. I was able to catch it in the act finally. This time the > problem wasn't a wireless issue, the devices were constantly disconnecting > and reconnecting at the switch level. > > I pulled the Cisco switch out and dropped in a Netgear unit. That didn't > fix it. Next I put in a Digital Loggers rack mount reboot device. That > wouldn't connect right either. > > I finally had to pull all of the hardware off of the shelf and set most of > it on the floor (or just let it hang there) to get it working at all well. > Still not perfect but better. > > I had by now hiked up there through sometimes knee deep snow 3 or 4 times. > Next I took a motorbike with studded snow tires up and got permission to > turn down the power to the radio station. That didn't fix the problem > either. > > Next I borrowed a snowmobile and hauled some help and my spectrum analyzer > up. I was unable to see any signals that didn't belong. > > Next day, another hike up the hill. > > OK, maybe a cat 5 cable went bad and I'm getting backfeed through the > switch. DC current or something. So I started testing the cables that > run > to the most problematic units. Well now, look at that. Bad cable. In > fact > there are three of them. Hmmm, kinda strange though. All three have the > exact same fault! Oh well, better change them out anyway. I ran three > new > cable runs and just for kicks I tested one of them. What the heck????? > The > new cable has the EXACT same fault as the old one! Even though it didn't > follow the exact same path as the old cables. > > Man, this is sure looking like a problem caused by the radio station. I > was > using indoor cat5 and didn't run lightning protection or ground anything. > Yeah I know, but remember that this has been there for a very long time > like > this. And as a guy with an electrical background I know that there are > actually two ways to deal with stray electrical. Grounding is one. > Insulating is another!!!! Anyway, I know it wasn't built to specs. > > I added some grounding and that didn't help at all. > > Yesterday I finally had one of the local wireless companies (Day Wireless) > that mainly does VHF radios, backhaul etc. They also checked things with > the spectrum analyzer but couldn't find anything amiss. I was able to > duplicate the wiring fault for them (with my Ideal tester). But suddenly > everything cleared right up! Stuff was looking good, no cable fault etc. > Pings were looking good, devices were finally negotiating the connections > right etc. > > I called the radio station to ask if I could try turning the power down > again to see if we see any change on the spectrum analyzer. They said > they > thought that I'd already done that because the showed the power was way > down. Turns out someone in the building had bumped a breaker and shut > down > part of the transmitter! Well, we got all of that figured out and guess > what. All of the problems came right back! I then turned the power back > down and they cleared up. > > Tip for you guys, dropping an 18,000 watt system down by even 60% of it's > normal output isn't always enough. We had to drop down to 10 to 20% to > get > the problems to clear up. The guys from Day Wireless had some small > ferrite > beads with them so we stuck them onto the cables. Put the beads on and > the > radios would negotiate at 100full. Take them off and they'd drop right > back > to 100 half. Duplicatable all day long. > > Soooo, current theory is that the radio station is screwing up my cat5 > connections. The fact that the building has less hardware in it and we > have > more snow up there than normal has probably caused some different eddy > currents or multipath. Or some other such strangeness. > > I have some shielded cable and connectors on the way. I have permission > to > move my gear from one side of the building to the other side. I've got > more > high end ferrite beads on the way (one that is made for cat 5 and is big > enough for three wraps to go through it). Not the little $.50 ones, these > are nearly $6.00 each. > > I also have a Fluke DTX on the way. > http://www.flukenetworks.com/fnet/en-us/products/DTX+CableAnalyzer+Series/ > They rent for $650 per month from http://www.trs-rentelco.com/ List is > over > $7000. If I like it I'll probably get one and add it to my two spectrum > analyzers and my bucket truck. grin > > Never ever forget that wireless is 50% science and 62% black magic! > > I am quite hopeful that the new cable, beads on bother ends of the cat5, > better grounding, and an equipment move will fix this site up nicely. If > not, who wants to buy it? lol Seriously, this site and one of the ones > that it feeds cause nearly 80% of my trouble calls. With any luck it > wasn't > wireless trouble that I've been having all along. Shrug. > > Here's the really strange part to all of this. The hardware that cost the > most has the most trouble! grrrr > > Also, the Day Wireless guy had some kind of wide band sensor. He could > move > it around and see where overall signal levels were unsafe for people. > Right > beside a 4" or so copper pipe that the radio station used as a wave guide > was pretty bad. A couple of inches from it was ok. The next highest > readings at the whole site? RIGHT a the BASE of the 100' wooden pole that > everything is mounted on! And what did I do when I installed all this new > gear a year ago? Yeah, I put the antennas up top and the radios right > down > at the base of the tower so I could get to them without having to rent a > lift. Dang the luck! > > Hope that this helps someone else out. > marlon > > > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: [email protected] > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: [email protected] Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
