OK, can we put this in plain English? What freq. does 100meg ethernet in full or half duplex???? marlon
----- Original Message ----- From: "Josh Luthman" <j...@imaginenetworksllc.com> To: "WISPA General List" <wireless@wispa.org> Sent: Wednesday, January 07, 2009 9:07 PM Subject: Re: [WISPA] FM radio station site strangeness > With 100BASE-TX hardware, the raw bits (4 bits wide clocked at *25 MHz* at > the MII) go through 4B5B <http://en.wikipedia.org/wiki/4B5B> binary > encoding > to generate a series of 0 and 1 symbols clocked at *125 MHz* symbol > rate<http://en.wikipedia.org/wiki/Symbol_rate>. > The 4B5B encoding provides DC equalization and spectrum shaping (see the > standard for details)[*citation > needed<http://en.wikipedia.org/wiki/Wikipedia:Citation_needed> > *]. Just as in the 100BASE-FX case, the bits are then transferred to the > physical medium attachment layer using > NRZI<http://en.wikipedia.org/wiki/NRZI>encoding. However, 100BASE-TX > introduces an additional, medium dependent > sublayer, which employs MLT-3 <http://en.wikipedia.org/wiki/MLT-3> as a > final encoding of the data stream before transmission, resulting in a > maximum "fundamental frequency" of* 31.25 MHz*. The procedure is borrowed > from the ANSI X3.263 FDDI > <http://en.wikipedia.org/wiki/FDDI>specifications, with minor > discrepancies. > [3] <http://en.wikipedia.org/wiki/Fast_Ethernet#cite_note-mlt3-2> > > Source: http://en.wikipedia.org/wiki/Fast_Ethernet > Josh Luthman > Office: 937-552-2340 > Direct: 937-552-2343 > 1100 Wayne St > Suite 1337 > Troy, OH 45373 > > Those who don't understand UNIX are condemned to reinvent it, poorly. > --- Henry Spencer > > > On Thu, Jan 8, 2009 at 12:02 AM, Marlon K. Schafer > <o...@odessaoffice.com>wrote: > >> So far all I can find on the internet is that ethernet is at either 12.5 >> or >> 31.25mhz. NOT 350, that's gigE, not 10/100. >> >> Also, this tower is a 100' wooden pole. Can't move anywhere really. >> marlon >> >> ----- Original Message ----- >> From: "Adam Goodman" <a...@wispring.com> >> To: "WISPA General List" <wireless@wispa.org> >> Sent: Wednesday, January 07, 2009 9:15 AM >> Subject: Re: [WISPA] FM radio station site strangeness >> >> >> > It also sounds like there is a new leak in the waveguide. One more >> > thing you might try is to move the cable from leg to leg on the tower >> > so that you variable length sections that do not resonate at 350MHz or >> > ~100MHz (FM transminssion). >> > >> > >> > On Wed, Jan 7, 2009 at 11:16 AM, Adam Goodman <a...@wispring.com> >> > wrote: >> >> We also colocate with an FM transmitter. Only 1300W though. we also >> >> had interference on our Ethernet lines. We solved it by moving radios >> >> away from the FM antenna (3 feet or so on a 90' tower) We also >> >> installed ferrits which helped (I actually used a conduit pipe). >> >> Grounding the cat5 helped too. >> >> >> >> I would think that if you find that you need more shielding. put all >> >> your cat5 cables in a conduit and install abreakout box at the top of >> >> the tower. If your area is prone to electrical storms (where isn't >> >> these days?!) you will at some point be very sorry you didn't grount >> >> (and well!!) >> >> >> >> >> >> >> >> On Wed, Jan 7, 2009 at 10:47 AM, Marlon K. Schafer < >> o...@odessaoffice.com> >> >> wrote: >> >>> 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! 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