Building To Building

Where does it get it's electrical power from? Think about doing it in a low cost way, rather than think about doing things the high tech expensive way. Chances are, if it is a building on a farm, the electrical comes off a transformer by the street and, then routed to the buildings.. Means there is already wiring between the buildings. They not only make "power line networking", but they also have phones, intercoms, radios, tv, multimedia, etc over power lines. For devices with a ethernet and/or USB jacks that plugs into AC plugs, and run at speeds of about 10 Mbps... Check out

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If you are curious, the devices that plug in at various locations are about $50 each. (you will need two, so it will be about $100)

Reply to
Peter Pan
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I'm certain the question has been asked before about how to setup a simple wireless connection between two buidlings; so, I apologize for being repetive.

The application is on a farm. I am using PC's running Windows 98se. Presently I have a wired network setup. There is a cable modem, hooked into a router. Two PCs are also hooked into the router; these PCs share files and the internet connection. There are also two network webcams hooked into the router (this provides us with offsite, remote monitoring ability). None of this equipment is wireless. (The router is about 50' from the exterior wall of the building that faces Bldg2 - see below.) All of the above is in Bldg1.

There is a second building, Bldg2. A stand-alone PC is in Bldg2, it has no network connection. Bldg1 and Bld2 are 150' apart and in direct line of site. The computer in Bldg2 is about 15' into the interior and not in direct line of site with Bldg1. I want to connect the PC in Bldg2 with my network in Bldg1 in order to share the internet connection. It is not practical to run a wire between these buildings.

Any suggestions on how to do this. I am willing to replace the router in Bldg1 with a wireless one (prefer to use Linksys). Also, I prefer to hook into the PC in Bldg2 using a wired ethernet card (already installed in the computer) so I assume that I will need either a wireless router or AP in Bldg2 which I then plug the computer into.

Thank you for any guidance you can give me.


Reply to

Too bad, when you said it was a farm, I was hoping one drop.. Oh well, If you ever have a yacht, they work great off a single generator.. :)

Reply to
Peter Pan

Thanks for the suggestion about powerline networking devices. I had considered this; however, the two building are on two completely different services (meters, drops, etc.) Also, there is not common telephone service between the buildings.


Reply to

ability). None

above is in

router in

Seeing how you like linksys, a couple of wap54g's would work. You can run them both in bridge mode, or if you want wireless in Bldg1 you can run one of them in AP mode and the other in AP Client mode.Just connect the one in Bldg1 to your existing router and the one in Bldg2 to the ethernet card. If you can place both near a window facing each other it might work right out of the box. If you dont get a good connection you can always put a different antenna setup on them.

Reply to



Because of the number of devices you currently have connected to your existing router it probably would be best to keep it as is and simply add a wireless link between the buildings.

Several different Linksys models will do what you want, as will equipment from other manufacturers. I personally would use WRT54G units, even though they are overkill for what you want. They are very common, inexpensive, and are supported by third party firmware which makes them very versatile. (Who knows what you'll think of to use all of this for in the future...)

The trick with a link between buildings in understanding what "line of sight" means with a 2.4GHz radio path. No trees, no walls, and no occasional vehicles, all of which can block the signal. Walls made only of wood are not good, but can be dealt with. Walls that have aluminum foil backed insulation, have chicken wire to hold up plaster, or are made of concrete, will totally block the signal. So will trees or shrubbery that you cannot see through, as will any vehicle parked in the wrong place.

Hence... indoor antennas are best if placed in a window on an upper level. Outdoor antennas are a problem because the gain they provide is lost in the feedline unless you buy expensive semi-rigid coax. Mounting the equipment itself outdoors, on an elevated antenna mount, is another way to provide good service. Suffice to say, outdoor equipment is significantly more complex and expensive.

The ideal example would be facing second story windows in each building. Any number of different kinds equipment models could be used, but I'll describe a pair of WRT54G's.

Download third party firmware (Satori from Sveasoft or the latest HyperWRT firmware) and install it. Configure one unit as an AP and the other as a client. Mount them in the windows and run CAT5 cable to the router in Bldg1 and to the PC in Bldg2.

At 150' you should have a very solid link.

Note that if you do not mount the units in a window or use an external antenna that is outdoors, it will probably not work at all initially, and if it does it will almost certainly suffer from frequent signal dropouts. However, it might be possible, with experimentation, to find exactly the right place to locate the units where they will work.

I do the same thing with a building that is perhaps 100-120 feet away. The walls don't have any metal in them, and by moving each unit around and looking at signal strengths, I did find a place where they do work (one is at ground level, the other is on the second story because signal loss on the first floor was too frequent). Typical signal strength runs about -75 dBm or better, with occasional fades down to -81 dBm or so (caused mostly by multipath fading when vehicles drive by, or park, on the street between the two buildings).

Post more information about the specifics and you'll get significant input on your project as you go along. Different people here can provide real expertise on just about every aspect of your project. You don't need to ask right now about things like how to run CAT5 cable or how to configure your PC or the WRT54G, but when you get to those points... do post again as new hurdles need to be jumped.

Reply to
Floyd L. Davidson

You'll probaly benefit by directioal antennas at one or both ends. Google for "wifi cantenna", which should be fine. It's eith DIY or can be purchased.

In general, antennas need to be line-of-sight and the coax cable between the AP and the antenna should be as short as possible, a small # of feet, so yoiu wind up pulling enternet insode the house to reach the AP/antenna location. the AP can be powered over the CTA5 wire (google "POE power over ethernet") People put the AP antenna outside in weatherproof plastic boxes.

Reply to
Al Dykes

(snip long description of what is essentially: two buildings ~150ft apart, router in one 50ft from wall, PC in 2nd, unspecified distance from wall)

Aside from using powerline networking, I'd suggest putting a wireless AP close to the outer wall of building 1, with an antenna on the outside facing building 2, and a similar wireless reciever in building 2 with an antenna facing building 1. Some APs can be set in reciever mode (i forget the proper name for the mode).

Reply to
Mark McIntyre

Thanks to all who have replied.

Floyd from Alaska seems to have keyed in on a simple setup that I can handle, but I still have a couple of "novice" questions.

  1. Using two WRT54Gs will work for me. When setting these up I presume that in Bldg1 the WRT54G is configured as an access point and hooked via a CAT5 cable to my existing router. Is this correct?

  1. Bldg2 will have the WRT54G configured as a client and I hook this via CAT5 cable to the ethernet card in the computer. Correct? The WRT54G in Bldg2 will sit near a window with clear line of site to Bldg1.

  2. Bldg1 is a metal building. I can place the WRT54G near the exterior wall, but I presume an external antenna placed on the outside of the wall (facing Bldg2) would greatly help the signal. Any suggestions on which antenna to buy?

Again thanks to all.

Reply to

Yep. Either the WAN port or one of the 4 LAN ports can be used. I use a LAN port.

Make that *in* the window!

Note that either end could be the AP and the other the Client. The end that is an AP can have other wireless clients connect to it, while the end that is a client cannot.

Another possibility is to make *both* ends an AP, and enable one of them as a WDS repeater. This allows other wireless clients to connect to it too, but has the possible disadvantage that the througput is cut in half. That may or may not be significant.

Because wireless operates with simplex radios, using the same channel for both transmit and receive, they can't do both at the same time. Hence in normal operation the radios switch back and forth between transmit and receive. The actual maximum throughput will be about half the rate that data is transmitted at (because half the time is spent receiving). Hence an 802.11g unit is a 54Mbps unit, but because of the simplex operation (and packet overhead), the actual maximum bitrate you'll see is probably right at about 26Mbps or a bit less.

If the unit is used as a repeater, it has to transmit in both directions, as well as listen in both directions, hence the bit rate gets halved again.

However, if most or all of your traffic is directed to a typical Internet connection, which will be more than an order of magnitude slower, it simply won't make any difference. It would show up on file transfers, for example, between local hosts connected via the wireless network. Running an X window display over a wireless is noticeably slower than a 100Mbps ethernet, but faster than a 10 Mbps ethernet.

It makes no difference where you place the unit inside a metal building, it simply will *not* go through the walls. It must either be in a window, or have an external antenna.

To use an external antenna you need to put the unit as close to the antenna as possible because at 2.4Ghz the loss through almost any kind of practical feedline is relatively great. It makes no difference what kind of feedline you use if it is 100 yards long! That's almost like going through the metal walls! (Actually, 100 yards of cheap coax cable does have a name. It's called a "dummy load", which is a useful device for testing transmitters without actually radiating a signal.)

Note that the distance from your PC, which is connected with CAT5 using ethernet, is not really important at all. It could be a few hundred feet long and work fine. Hence you want to put the WRT54 right at the point where the feedline to an external antenna enters the building. You want that to be as near as possible to the point were an external antenna can be mounted with a clear line of sight view of the distant antenna. Think in terms of inches of feedline rather than feet! 100 inches is a lot of feedline unless you spend some real money on something like 1/2" semirigid coax or even larger heliax. If you use typical 1/2" low loss coax, keep it less than 6 feet long if at all possible. If you use even smaller coax, think about less that 24 inches.

To be more specific, the loss through coax runs something like

0.1 to 0.5 dB per foot. A 3 dB loss is the same as reducing your transmit power by 1/2. Even good coax is going to eat half your transmit power with a 30 foot length of line, and with less than optimal coax... well its a nice dummy load.

What you need depends on the structure of your building. Post a few more details, and we can probably tweek Jeff Liebermann into providing the right part numbers for coax. He can also advise you about antennas too.

Reply to
Floyd L. Davidson

Well, the official maximum length is 100 meters (328ft). However, if you're careful, you can go much further. 100baseTX will not work because the timing on the collision domain limit the cable length to about 500ft. I've had problems with 100baseTX whenever I tried it.

100baseTX-FDX (full duplex) is even worse due to crosstalk errors.

The only way to make it work is using 10baseT-HDX (half duplex). I think that the WAP54G and WRT54G allows forcing the interface protocol to 10baseT-HDX but only on the WAN port. The LAN ports are running the NWAY protocol and will set their own speed. Not good. So, my usual fix it to excavate out of the junk heap an old 10baseT hub. The hub goes between the WRT54G LAN port and the typical ethernet switch. Ugly, messy, but effective at keeping the speed at 10mbits/sec. Sometimes, I have the luxury of a managed ethernet switch available, which allows me to select the speed of an individual port. No hub required for these.

Anyways, for 10baseT to the wireless router LAN port, I've been able to hang 950ft of cable. Actually, it worked through the entire 1000ft roll of CAT5E, but I needed 50 ft before it was installed.

Why me? Never mind, don't answer.

My favorite coax cable is LMR-400 from Times Microwave:

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'll need a crimping tool ($40), a pile of RF Industries male N connectors ($5/ea), and a pigtail to connect to the access point ($18). If you don't wanna make your own, then you can purchase pre-cut and connectorize lengths:
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(See "cables section")

At 2.4GHz, LMR-400 looses 0.068dB/ft. I haven't worked out the link budget or fade margin so I don't know how much loss your link can tolerate. Too many unknowns. However, let's say you don't wanna loose more than a total of 6dB in the coax and connectors. The pigtail and 3 sets of connector pairs will eat about 3dB. That leaves

3dB loss available in the coax cable. At 0.068dB/ft, that's 44ft maximum coax. That's not too horrible for short links using fairly high gain antennas. However, since a 50ft jumper cable with connectors costs about $50, you might wanna think about mounting the radio near the antenna and using CAT5 to connect to the computah, as Floyd D. suggested, instead of using all that coax. Anyway, give me some specs and I'll work out the link budget and recommend antennas. One spec that I need is the MINIMUM acceptable thruput in mbits/sec.

I'll do a preliminary guess and suggest you adjust the numbers accordingly. We have a "half mile" range and I'll assume you're going to follow our advice and NOT use a huge coax run. Medium size dish or panel antenna on the OUTSIDE of the building. 1-3ft LMR-240 coax pigtail with R-TNC and N-male connectors. I'll assume a speed of

12Mbits/sec OFDM which will yield about half that in thruput speed. TX power = +15dBm TX coax loss = 4dBm TX antenna gain = +14dBi Distance = 0.5 miles RX antenna gain = +14dBi RX coax loss = 4dBm RX sensitivity = -84dBm (12Mbits/sec OFDM) Desired fade margin = ????
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a fade margin of 20.8dB which is just fine. This should work. However, everything you do to compromise the above calcs will cause reduce the fade margin. When it gets down to about 15dB, it will become flakey and unreliable.

So, you need antennas with a gain of about +14dBi. See:

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"antennas parabolic" and "antennas panel". I like the Maxrad panels (mostly because they're cheap and simple).

Reply to
Jeff Liebermann

Fran has sworn me to secrecy. I'm not allowed to talk about her on The Internet!

That is because somebody who knows her in Chicago clued me in that she won't wear seat belts, even in Chicago. (I don't here either, but I drive Suburban, and rarely ever go more than 25 mph, which makes it only half as crazy. Any place other than Barrow... I won't move even *one foot* without a seat belt on.) Anyway, it seems they have fits with her, trying to get her to use a seat belt. She puts the belt over her lap to look like its there, but won't buckle it.

(For everyone else's benefit, Fran is about 70 years old, can easily wear out two healthy people half her age on any given day, and is just more fun than I can possibly describe.)

Anyway... I was told about this seat belt stuff, so I go over to Pepe's North of the Border Mexican Restarant (and Fran always sits down and has a chat with me for all or most of the time I'm there). I tells Fran that I've got _the_ scoop on her. She told me I was goofy as a loon in the spring. I said, no really! I have spies, and they report to me on the Internet. So she, in total disbelief says something to the effect of I'm bullshitting her, and it just ain't so. So I looks her dead in the eye, and says, "Fran, they tell me you won't wear a seat belt in Chicago! Shame on you!"

She shrieked and jumped a foot in the air! hee hee heeeeeeeee.

Now, what you might not know is that besides own What she actually is, is an EE who came to the North Slope right after oil was discovered a Prudhoe Bay as the field engineer for the installation of power plants on oil drilling rigs.

She also knows personally every jazz musician in the country. And about 30 years ago she was on Johnny Carson's show, and presented him with a polished petrified penis bone from a walrus, and let him spend considerable time examining it before she told him exactly what it was.

Guess I better shut up...

Reply to
Floyd L. Davidson

She's already on the internet:

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Reply to
Jeff Liebermann

Floyd and Jeff thank you both for extremely thoughtful and complete replies to my inquiry. I won't pretend that I fully understand the significance of all the details you both have given me; if I did I would not have needed to ask the question in the first place as to how to accomplish the simple task of running a wireless network connection between two buildings.

That being said I believe between your posts I have sufficient information to get the job done. I will follow the advice from both of you and put the radio device in Bldg1 to achieve the shortest possible antenna run, no more that 6 feet. Jeff's information on the antenna and the links provided are exactly what I was looking for. Thanks much. I check back if I run into trouble when setting this up or with the configuration.

Floyd, just thought I'd ask if you know Fran Tate from Barrow. I hear her occassionally on Chicago radio - what an interesting personality.


Reply to

I'd never seen these before!

This article is confused about dates, but not in any way that makes a difference.

That one is very well done! Note that Jim Vorderstrasse, who is quoted frequently, is just about as much a character as Fran is!

That one is a good article too.

Beyond description really.

In fact, there is a major part of what Fran is that is not told in any of those three articles, though there is a hint of it. They mention things she does around Barrow... easter, and so on. But note that people in Chicago know her too. So do folks in Nevada, and parts of California and in East Saint Louis.

For perhaps a dozen years, which unfortunately had to end the past year, Fran has gone to a children's hospital in Chicago and handed out a fuzzy stuffed animal of some kind, with a smile and some cheer, to every child in the hospital. For the last couple years I helped her select the particular stuffed animal that she ordered (something like 900 of them).

For the past two or three years she adopted an elementary school in East Saint Louis. I don't remember the name of the school, but it was described to me as "the poorest school in the United States". This year we picked wool beenie hats (because one size fits all), and she sent 500 hats to the school, one for every child there.

When I say "we picked", let me add at little more to this story, because while that "we" does include me, my part is very very small. I happen to have a logo on the side of my truck that says "LaBamba Gift Shop" and on occasion I've been referred to as a "partner". Actually I'm not, but I've been known to hug the lady who owns it. She would also cut my head off if she knew I mentioned her name, but Stacey Cha is the owner of the LaBamba Gift shop. She was born in Korea and educated there, before coming to the US in the early 1970's. I don't want to say too much, but lets just say she was definitely not an under privileged young lady growing up in Korea!

She and Fran get together and plot these projects. It is Fran doing it, but Ms Cha makes it easier. She is in the business of buying these various types of items, so she finds reasonable sources to make bulk purchases, and gets them at cost for Fran. (When Fran had dealt with other local merchants in the past, they saw it as a great money making deal, and offered Fran a 5% discount...)

You just can't imagine how much fun it can be to have dinner with these two ladies, which I get to do on a regular basis. Quite the privilege!

(Of course... there's more to this whole story! Fran's son Joe, who must be about 50 now, is just as much a character as his mother. He ran the water deliver business for 24 years, but retired from that a couple years ago. We tease him that the only way to get water from him now is 1 glass at time, at Pepe's. Whatever, his house is literally a museum, with more local art and artifacts than the local museum has. And, yes he does give tours.)

And for anyone thinking of a trip to Barrow... I get 2 or 3 people I meet on Usenet a year that visit. I'm retired, so I have no problem spending a couple days showing off the local highlights. Certainly dinner with Fran and Joe is one of the things we do. Anyone who has a real streak of adventure running through their bones is encouraged to give it serious thought, and let me know about it.

Reply to
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