Re: [WISPA] FM radio station site strangeness
There are pseudo square waves on ethernet. Those have an infinite number of harmonics. - Original Message - From: Brian Rohrbacher To: WISPA General List Sent: Wednesday, January 07, 2009 10:11 PM Subject: Re: [WISPA] FM radio station site strangeness I installed a cat5 cable next to a guys police scanner one time and as soon as I plugged the cable (lan cable from poe to computer) in the police scanner stayed keyed up on 15o or 155 mhz as I remember. Unplugged the cable and the scanner started scanning again, so I always thought it was 150 some mhz. Brian Marlon K. Schafer 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
Re: [WISPA] FM radio station site strangeness
I'm sure if you looked at it on a spectrum analyzer you'd see the signal occupies a wide band of frequencies, hence it's probably susceptible to interference on a wide range of frequencies. Greg On Jan 8, 2009, at 12:54 AM, Marlon K. Schafer 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 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 ratehttp://en.wikipedia.org/wiki/Symbol_rate. The 4B5B encoding provides DC equalization and spectrum shaping (see the standard for details)[*citation neededhttp://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 NRZIhttp://en.wikipedia.org/wiki/NRZIencoding. 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/FDDIspecifications, 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.comwrote: 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
Re: [WISPA] FM radio station site strangeness
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. S, 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
Re: [WISPA] FM radio station site strangeness
We had a site with a 1000 watt AM Hotstick about 100 feet from another tower. We ran the cable (non-shielded outdoor rated) and crimped the end at the top of the tower. The installer all of a sudden, felt a burning sensation on his thumb with that wonderful smell of burning skin. Guess what, he was holding the end of the cat5, not plugged into anything, just ran up the tower! Sure enough, nice little burn marks right where the copper pins on the cat5 was! Put in a few ferrite beads, never looked back. fun stuff to say the least. ON a side note, we are at 400 foot on a 1400 foot FM tower transmitting at 100,000 watts at the top. We ran Power up, but have a 440 foot non-poe cat5 down, and don't have any issues! lol -- * Dennis Burgess, CCNA, A+, Mikrotik Certified Trainer WISPA Board Member - wispa.org http://www.wispa.org/ Link Technologies, Inc -- Mikrotik WISP Support Services* *Office*: 314-735-0270 *Website*: http://www.linktechs.net http://www.linktechs.net/ */ Link Technologies, Inc is offering LIVE Mikrotik On-Line Training http://www.linktechs.net/onlinetraining.asp/* Marlon K. Schafer 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
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
Re: [WISPA] FM radio station site strangeness
Think wavelength. AM wavelengths are hundreds of feet long. There is a giant reactive near field around the AM antenna. (Electric fields and Magnetic fields) Your cat 5 was probing the electric field at two different voltage points. For AM broadcast frequencies, you can actually take a volt meter and stretch the leads out and measure the field on the AC voltage setting. One end of your cat 5 was tapping the field at a low potential region and the other end was at a high potential. Almost like you have one end of the cat 5 connected to ground and now you have climbed onto a high voltage power line and are handling the grounded cat 5. (Just your body being in the field is analogous to being on a high voltage power line). With the much smaller (relatively speaking) wavelength of the FM broadcast frequency, the cat 5 crosses multiple high and low voltage nodes in the field. Likely as to be self canceling. And since your cable is much longer than the FM wavelength there is very little chance it is resonant. Plus the inductance of the cable produces much more inductive reactance to the FM signal. However short cat 5 jumpers can pick up an enormous amount of FM energy and very little AM. - Original Message - From: Dennis Burgess - Linktechs.net dmburg...@linktechs.net To: WISPA General List wireless@wispa.org Sent: Wednesday, January 07, 2009 10:05 AM Subject: Re: [WISPA] FM radio station site strangeness We had a site with a 1000 watt AM Hotstick about 100 feet from another tower. We ran the cable (non-shielded outdoor rated) and crimped the end at the top of the tower. The installer all of a sudden, felt a burning sensation on his thumb with that wonderful smell of burning skin. Guess what, he was holding the end of the cat5, not plugged into anything, just ran up the tower! Sure enough, nice little burn marks right where the copper pins on the cat5 was! Put in a few ferrite beads, never looked back. fun stuff to say the least. ON a side note, we are at 400 foot on a 1400 foot FM tower transmitting at 100,000 watts at the top. We ran Power up, but have a 440 foot non-poe cat5 down, and don't have any issues! lol -- * Dennis Burgess, CCNA, A+, Mikrotik Certified Trainer WISPA Board Member - wispa.org http://www.wispa.org/ Link Technologies, Inc -- Mikrotik WISP Support Services* *Office*: 314-735-0270 *Website*: http://www.linktechs.net http://www.linktechs.net/ */ Link Technologies, Inc is offering LIVE Mikrotik On-Line Training http://www.linktechs.net/onlinetraining.asp/* Marlon K. Schafer 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
Re: [WISPA] FM radio station site strangeness
Do you have the shielded cable? Mark insert witty tagline here - Original Message - From: Marlon K. Schafer o...@odessaoffice.com To: WISPA General List wireless@wispa.org Cc: isp-wirel...@isp-wireless.com 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. S, 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
Re: [WISPA] FM radio station site strangeness
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
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 ratehttp://en.wikipedia.org/wiki/Symbol_rate. The 4B5B encoding provides DC equalization and spectrum shaping (see the standard for details)[*citation neededhttp://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 NRZIhttp://en.wikipedia.org/wiki/NRZIencoding. 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/FDDIspecifications, 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.comwrote: 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
Re: [WISPA] FM radio station site strangeness
I installed a cat5 cable next to a guys police scanner one time and as soon as I plugged the cable (lan cable from poe to computer) in the police scanner stayed "keyed up" on 15o or 155 mhz as I remember. Unplugged the cable and the scanner started scanning again, so I always thought it was 150 some mhz. Brian Marlon K. Schafer 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 c
Re: [WISPA] FM radio station site strangeness
Marlon, It has taken us almost 10 years at our single FM radio station location to figure out how to make things work at 100Mbps. This is one of the worst stations I have ever seen or heard about. In the "generator" room where we are located, the fluorescent light bulbs will actually glow enough to see with the light switch turned off. Of course, this is a 100KW FM station operating at 99.1, so that doesn't help. We started running shielded CAT5 cable (which we had done 8+ years ago), but nobody told us we had to use shielded RJ45 ends as well AND actually ground the drain wire to the outside of the RJ45 when crimping the end. The other thing we discovered is we have to use shielded CAT5 patch cables (to go from the PoE injectors to the switch). The last secret is if we are still having a problem with an ethernet link, by changing the length of the patch cable (longer or shorter) that will usually fix the problem. Travis Microserv Marlon K. Schafer 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
Re: [WISPA] FM radio station site strangeness
Not yet. I've got some on the way thought. marlon - Original Message - From: rea...@muddyfrogwater.us To: WISPA General List wireless@wispa.org Sent: Wednesday, January 07, 2009 1:08 PM Subject: Re: [WISPA] FM radio station site strangeness Do you have the shielded cable? Mark insert witty tagline here - Original Message - From: Marlon K. Schafer o...@odessaoffice.com To: WISPA General List wireless@wispa.org Cc: isp-wirel...@isp-wireless.com 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. S, 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
Re: [WISPA] FM radio station site strangeness
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 ratehttp://en.wikipedia.org/wiki/Symbol_rate. The 4B5B encoding provides DC equalization and spectrum shaping (see the standard for details)[*citation neededhttp://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 NRZIhttp://en.wikipedia.org/wiki/NRZIencoding. 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/FDDIspecifications, 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.comwrote: 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
Re: [WISPA] FM radio station site strangeness
I thought I'd try that too. marlon - Original Message - From: Travis Johnson To: WISPA General List Sent: Wednesday, January 07, 2009 9:12 PM Subject: Re: [WISPA] FM radio station site strangeness Marlon, It has taken us almost 10 years at our single FM radio station location to figure out how to make things work at 100Mbps. This is one of the worst stations I have ever seen or heard about. In the generator room where we are located, the fluorescent light bulbs will actually glow enough to see with the light switch turned off. Of course, this is a 100KW FM station operating at 99.1, so that doesn't help. We started running shielded CAT5 cable (which we had done 8+ years ago), but nobody told us we had to use shielded RJ45 ends as well AND actually ground the drain wire to the outside of the RJ45 when crimping the end. The other thing we discovered is we have to use shielded CAT5 patch cables (to go from the PoE injectors to the switch). The last secret is if we are still having a problem with an ethernet link, by changing the length of the patch cable (longer or shorter) that will usually fix the problem. Travis Microserv Marlon K. Schafer 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