Per my post from Wiki I believe it is 25, 31.25 and 125 mhz for fast ethernet 100base TX.
On 1/8/09, Marlon K. Schafer <[email protected]> wrote: > OK, can we put this in plain English? What freq. does 100meg ethernet in > full or half duplex???? > marlon > > ----- Original Message ----- > From: "Josh Luthman" <[email protected]> > To: "WISPA General List" <[email protected]> > 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 >> <[email protected]>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" <[email protected]> >>> To: "WISPA General List" <[email protected]> >>> 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 <[email protected]> >>> > 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 < >>> [email protected]> >>> >> 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! 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/ >>> >>> >>> >>> >>> -------------------------------------------------------------------------------- >>> 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/ > > > > -------------------------------------------------------------------------------- > 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/ > -- 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 -------------------------------------------------------------------------------- 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/
