Connecting Two Buildings on Ethernet

This is for all the noobs out there like me when it comes to Ethernet. We just tried an experiment to connect a Linksys Internet hub/router to a distance of 525 feet to another house nearby. The idea was that we couldn't get wireless to work that distance (even with the use of a cantenna), so we would try the wired approach. I thought I read it could go up to 600 feet without a repeater or hub, so we decided to give it a go. I have color-coded, snap-together Leviton connectors at each end which have usually given me good luck. The idea was that we would pull the wire as a test, and, if it worked, we would then bury line in PVC conduit.

We found it was a no-go, so I rewired each connector again, just in case. Still, no connectivity. I would reason to bet that Ethernet craps out after around 400 feet. I can't put a hub at 400 feet, unfortunately, because we don't have a power source and can't run a line that long.

So if you're looking to wire large distances like this, you might want to keep this in mind.

We found we just briefly were able to pick up the wireless signal with a cantenna, but it lasted only briefly and dropped. We were not able to recover the signal again. Therefore, we think we need about 3 more cantennas -- one for each antenna on the wireless equipment -- and we hope that this will help us. We're using Cantenna.com brand cantennas. The wireless signal was fast and reliable, however, at about 400 feet, right before any stretch of trees. Therefore, we're hoping with some extra antennas, we might be able to make it through the trees.

My relative is a nurse practitioner insurance adjuster with 5 kids, working from home for Blue Cross/Blue Shield. She just got out of a domestic abuse situation. We're doing everything we can to get her Internet going so that she can be functional again.

Reply to
Alfred Whitney
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Should be able to go 100 meters.

Can you put the antenna on a pole or something to clear the trees. Going through the trees will eat up the signal. What is the gain of the antenna you are dealing with.

Reply to
Dana

10baseT has a good chance of doing it, 100baseTX almost none.

It shouldn't be too hard to find a 10baseT repeater (hub) around, put that at one end and the other end will negotiate to 10baseT.

-- glen

Reply to
glen herrmannsfeldt

Dana's on the right track, I think. With the right antenna, this should work with no problems:

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The downside is weather... depending on the power budget, the link may go down in heavy rain conditions. For half a kilometer, it might just be easier to bury two strands of fiber.

Marc

Reply to
mrand

you need to maintain the pairing correctly and use good quality cable(Cat5 or better) - even then you are pushing the distance limit.

AFAICT 3Com make a switch designed for a US wallplate which can be powered via power over Ethernet - so if you have somewhere along the cable that electronics will survive in this may help split the run into 2 sub 100m links.

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2 alternatives:

pull fibre (not cheap)

someone suggested wireless LAN kit via a co-ax cable for a similar distance / visibility problem in alt.internet.wireless - not sure how you would connect this up (if at all), but you obviously have a cable route...

Reply to
stephen

Wireless or fiber would be preferred.

No indication of 10/100BaseT - what are you using for cable?

You might also watch for ground loops and noise pickup. Be very careful in lightning country, as differential ground voltages (ground is not ground) may cause problems. Your insurance carrier and local fire marshal may or may not be pleased.

Off you go to the 'alt.wireless.internet' newsgroup - please read the articles in the group before hand, as your problem has been reported and solved _very_ frequently.

  1. You need a "high gain" antenna at each end of the link.
  2. The antenna must be attached by the shortest possible length of cable (think _inches_ not feet) directly to the radios. Cable loss at 2.5 GHz in cheap cable is appalling - the typical coax used for CATV (RG58/U) is roughly 4 dB / 10 feet assuming perfect cable and no connector loss (highly unlikely situation), and that cuts the maximum range nearly in half. Making good RF cables is _far_ more difficult than making 100BaseT stuff - harder even than Gigabit cables, and a poorly assembled connector can have more loss than that 10 foot section of RG58 alone. The 1/8th inch cable (RG187) is even more lossy - 3 foot cuts the maximum range in half.
  3. The "line of sight" needs to be clear, INCLUDING the first Fresnel zone (for 525 feet, clear all obstacles by at least 7.22 feet)
  4. Home made antennas may not be suitable. Commercially made panels should work.
  5. Your 525 foot link has a path loss of roughly 85 dB in free space (the atmosphere adds some additional loss, and this assumes nothing is in the 8 foot radius about the direct line of sight). Assuming a +20 dBm transmit power, and effective sensitivity of -70 dBm (802.11g), you are about +5 dB S/N ratio - marginal. 10 dBi antennas at both ends with _NO_ cable loss should make things work, but something directly in the "line of sight" will cost an additional 6 to 30 dB of path loss.
  6. Keeping the cable length between the radio and antenna an an absolute minimum, try moving the antenna up to 15 feet up/down/sideways, and see if there might be a "null" to avoid.

Good luck.

Old guy

Reply to
Moe Trin

Moe Trin wrote: (snip on 525 foot ethernet connection)

(snip)

Well, you don't have to worry about ground loops, as ethernet is always tranformer coupled. Lightning could be a problem, but if you are careful, all you should lose are 10baseT repeaters, which are pretty cheap these days, most likely free.

You might find a fiber cable on eBay long enough, and with connectors already attached. 10baseFL media converters should be pretty cheap used, 100baseFX a little more expensive.

If you can't run fiber all the way you could connect a

10baseT/10baseFL media converter well grounded (as short as possible to a cold water pipe), and then run fiber to another media converter into the rest of the net.

-- glen

-- glen

Reply to
glen herrmannsfeldt

On the NIC, yes, but is the cable completely isolated? (Or as may be required by code, grounded at one place only?)

Years ago, I had a radio system on an airfield about 50 miles East of San Jose, with the monitor antenna located 100 feet from the transmitter building (that also contained the transmitting antenna as well as the actual monitor electronics). In accordance with FAA-ER-2100, everything was grounded six ways to Sunday. Well, we had a lightning strike, that hit the ground (video cameras happen to see it) about 500 feet from the transmitter (~450 feet from the monitor antenna). The monitor went FOOM!!! because as I wrote - "ground" is not "ground" and there was a substantial difference in the voltage at the 20 foot long ground rods at the monitor antenna verses at the transmitter just 100 feet away.

Highly recommended

Weeellll... when I bought the house I live in now, one of the many things I looked at was the grounding. Right next to the garage, I see a #4 AWG stranded copper attached to the 1 inch copper water supply pipe coming out of the ground. Looks great. (You can see this coming, right?) We've got high water pressure here (100 PSIG), and about 10 years after the place was built, the water line splits, between the city water meter at the curb, and the cutoff at the garage where it enters the house. Call the plumber to come out and replace the line. Turns out that copper line I can see ends a foot below grade, and changes to PolyButylene (non-conductive plastic) pipe for the run out to the curb. The only ground I really had was the neutral line of the electrical supply which is "grounded" at the transformer about a hundred yards away. And yes, we do get thunderstorms here - that's half or more of the annual rainfall.

Old guy

Reply to
Moe Trin

"Alfred Whitney" skrev i meddelandet news: snipped-for-privacy@i42g2000cwa.googlegroups.com...

I have a cable that is 650 feet to a friend, it worked fine with 10Base-T and we recently bought some PoE equipment and are now running 1000Base-T and it works perfectly.

Reply to
Ante

Moe Trin wrote: (I wrote)

I am pretty sure they are completely isolated.

Coax is much easier to ground, but even that isn't normally needed if it is within one building.

UTP probably could be grounded with a center tapped transformer, but it would have to be done pretty carefully to maintain balance needed to avoid RFI problems. There would also need to be a way to select which end was grounded, and there would be problems when both ends were accidentally grounded.

-- glen

Reply to
glen herrmannsfeldt

Yes that can happen. A heavy ground wire back to the transmitter ground would have worked much better. I believe that some codes now require that all ground sources be bonded together.

Reply to
Thomas Schulz

That should have been FAA-G-2100 which refers to FAA-STD-019 (Lightning and Surge Protection, Grounding, Bonding and Shielding Requirements for Facilities and Electronic Equipment). They say memory is the second thing to go when you get old.

I don't have the documentation/diagrams/etc. any more, but I know there was at least one ground wire connecting the two (ground for the power to the obstruction lights on the tower as well as a weatherproof outlet at the base), and I don't remember any damage to that wire (which was probably only a #10 AWG or about 0.1 Ohm). I haven't seen the FAA documents in years, so I don't know what (if any) changes have been made in more recent editions, but the FAA (and before them, the CAA) have been putting this (or similar) kind of installation on airfields since the late 1930s. Maybe they're playing the odds that the probability of a direct hit or near miss is pretty low.

Old guy

Reply to
Moe Trin

We found the solution. For $700, you can purchase the XPress Indoor Ethernet Bridge:

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We implemented it and went from a different house this time, farther away. We went a distance of 1000 feet through about 250 feet of trees. In one house, we put the device behind two walls on a second floor. On the other house, we put the device through one wall on the first floor. We edged out a reliable 650Kbps as long as no 2.4Ghz phone was kept nearby, and that's even though the device operates on 900Mhz. And we implemented this without Yagi antennas. We were able to achieve reliable VPN over it for several hours, sharing my DSL line for this relative.

The guys at

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said that 900Mhz works better for longer point to point communications and is less crowded in that spectrum.

So I went "war driving" (in a sense) with it. (Technically it's not war driving because the device is encrypted point to point communication on its own proprietary protocol.) We found it had a range of about 2500 feet through thick woods here or there and that was without using a pole or Yagi antennas.

So anyway, I highly recommend this device. If you don't need the Yagi's, then great. If you do, then consider them and a pole off the roof of your house or garage. The guys at MaxStream, however, warned that you'll want to keep the Ethernet bridge as close as you can to the antenna -- a long cable could reduce the transmission and receiving power.

Oddly enough, after we implemented this solution, Verizon gave our relative a call and said, "Yes indeed we think we might be able to put DSL at your house. We will make an attempt." So we'll have to see how that goes. If the DSL actually works for her, then we'll have to ship this product back, unfortunately. (Dang, I wish I had the need to keep it because it's so cool.)

Reply to
Alfred

As discussed:-

PoE switch half way - 3Com Intellijack for example (~$100) Needs PoE power source too but that is easier to locate.

Two SDSL routers back to back (not ADSL) ZyXEL P791R Single Port SDSL Router ~$120 each 2Mbps uses phone wire. Some people do 4 wire versions that go faster.

Reply to
Bod43

Pricey, but if that's what it takes...

Obviously, results are going to be dependent on how thick those trees are, and how much moisture are in the leaves. The web page says

Power Output: 125 mW (21 dBm), 4 Watts EIRP Indoor/Urban Range: 1000' (300m) w/ 2.5 dB dipole antenna Outdoor/RF Line of Sight Range: 15 miles (24km) w/ high-gain antenna

Receiver Sensitivity: -97 dBm

and a quicky number crunch says +21 + 2.5 - 81.4 (1000 ft @ 915 MHz) +

2.5 = -55.4 dBm received (free space). Fresnel clearance, trees and those walls can eat up a lot, but at the moment you have about 41 dB of reserve gain.

That's interesting, as 2.4 GHz phones have no harmonic relationship to

915 MHz. (2.67:1 or 8:3).

Well, yes and no. 900 MHz requires more ground clearance, but path loss is a function of 20 * log F. It's also less effected by atmospheric conditions (rain/snow/fog), but if things get wet...

Definitely - even more so at 2.4 GHz. The (nominal) quarter inch coax (RG-58/U) has a loss of 20 decibel per 100 feet at 915 MHz resulting in a 10:1 reduction in range. At 2.4 GHZ, the loss is about 38 decibels which is an 80:1 reduction in range. That's why we talk about cable lengths measured in small numbers of inches.

Old guy

Reply to
Moe Trin

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