How can I use a buried cable TV cable to connect my house and my barn for home networking? Or, how can I use it as an extender so I can locate a DirecWay “satellite modem” out there?
I want to get broadband, which so far where I live means satellite. But there’s no view of the southern sky from my house, even if I erect a 60’ tower. There is however a view from my barn 150’ distant, and I already have a DirecTV dish out there for television. I buried two cable TV cables (I think it’s RG-56 but that’s just my recollection) because we have two receivers in the house, but wouldn’t mind too terribly losing one of them.
To have one TV receiver plus satellite internet would require 3 cables to the dish (one TV, one internet uplink, one internet downlink - so they tell me). But it was a big expensive job to bury cables, and I wasn’t smart enough to bury extras.
So I wondered if I could put the “satellite modem” out there in the barn, and connect its ethernet jack to the ethernet side of a “cable modem”, and connect the cable from that “modem” to a second one in my house, and tie that to my hardwired ethernet. The extra stuff required would therefore be two “cable modems”. which might be $100 or $150 total - not so bad on top of the $600 satellite gear. I think this would be called a coaxial cable bridge. And, yes, there’s power out there.
I’m pretty sure I could use two wireless devices to make the bridge, but that would cost maybe $400 to $500 extra for two wireless devices and two antennas to span the long distance. Besides, I don’t really trust wireless for security reasons.
It would definitely be nice to have the barn networked, because I could also put some sort of backup server out there if I wanted, and have secure backup even in the case of a fire.
Anyone know if this would work? Would they be standard cable modems or something special? The cable runs about 200’ (it couldn’t run straight).
Caveat Emptor: my experience with CATV networking was on Biosphere II, using late eighties technology. I don’t think you can get there from here, at least easily.
The cable ether modems I worked on were pretty early technology but worked by having two frequency bands, inbound and outbound. Singnals originating at the modem travelled toward the head end of the system on an inbound channel. At the head end the signal was translated into an outbound channel and sent back out so all the cable modems on the system could recieve it. Putting two of those modems on a segment of cable would result in nothing, both would transmit packets but there would be nothing on the appropriate channel to recieve. I am not 100% certain that present cable modems work the same but I’m assuming they do.
There are other solutions and much cheaper but you’ll have to bury a different kind of cable. IIRC regular coaxial ethernet can go 1,000 feet between repeaters but you’ll need 50 ohm cable, not 75 TV cable. It’s stretching the limit of twisted pair at that length but it might work and you could use a dirt cheap ethernet hub at the other end.
Trying to use a standard cable modem would be proibitively expensive. Cable modem technology is asymmetric: the cable modem termination device used in the residence can only be used on one end. The other end is a branch office cable modem termination system combined with a complicated head-end injector. Such systems have pricetags in the five to six figure range (and require substantial expertise and equipment to install) and would be totally out of line for your application. As far as I know there’s no way to modify a residential CMTD to act as a head-end instead of a tail-end.
However, you may be able to use the cable as a conduit for classic, old-fashioned broadband Ethernet – what used to be known as “thickwire” Ethernet, or 10-Base-5. This was the original Ethernet technology introduced back in the 80s. Thickwire was called that because it used RG-8 cable, which is about a half inch in diameter. It still works, but isn’t used much anymore.
You’d have to get your hands on a couple of thickwire transceivers and on hardware to drive them – probably have to find all that on eBay as not many people use this technology anymore. Most thickwire transceivers require the standard AUI interface, which isn’t found these days on that many systems. Some older 3com cards have them, many older hubs, and of course all Cisco 2500 series routers.
Caveat: the frequencies used by thickwire may conflict with your satellite TV signals. I’m not familiar with the technologies used there. I do know that it was possible to piggyback thickwire ethernet with standard video cable, but I think they’ve since reallocated those frequency ranges to carry video as the number of channels carried has increased. You’d have to either get the specs for both systems and compare them for conflict, or else get your hands on a spectrum analyzer and check directly for conflict.
Also, thickwire requires 50 ohm cable. If your cable is not 50 ohm (many video systems are 72 or 75 ohm) you will need to use an impedance matcher at the injection point (or else have degraded performance that may be unacceptable).
KellyM, I like the thickwire idea. By “transciever” do you mean something that translates between twisted pair ethernet and coaxial ethernet? If by “card” you mean something that plugs into a PC, wouldn’t that require maintaining two PC’s at the ends of the coax link? Also, is a 50 to 75 ohm impedance matching transformer a standard part, or would I need to wind my own ferrite toroid (like I’ve done for radio)?
Any of the solutions that require burying different cable are solving the wrong problem. If I was going to bury cable, I’d bury the kind DirecWay wanted in the first place - or run my twisted pair ethernet out to the barn - or maybe both, like I wish I’d done last time.
I’ve never seen a media converter from 10-Base-T to 10-Base-5, although there might be one out there somewhere. My recommendation would be to use an older hub that has an AUI port in addition to 10-Base-T ports; this will act as a media converter. The transceiver is the device that converts the digital signal on the AUI interface into the RF signal that goes over the cable (hence the name “transceiver”), and, of course, vice versa. Keep in mind that we’re talking about antiquities here. I haven’t used any of this stuff in years. The media converters I deal with nowadays convert between 100-Base-TX and 100-Base-SX.
I imagine you can find an appropriate impedance matcher or wind your own, either way.
Have you considered open-air near-infrared optical? I’ve seen some very reasonably priced systems for open-air optical networking, and those would be more secure than RF wireless. (You would obviously require line of sight for that.)
Just to add I have heard of some wireless networks that have been modified to be unidirectional (and at an extreamly increased range) - using coffee cans. A wireless bridge should cost less then $100.
It sounds like you can use “Thinnet” (10 Base 2) as long as you are ok with dedicating one of the cables you burried to the network. Thinnet is basically Ethernet over a standard 50 Ohm cable (which I assume is what you have burried). According to this site and this site, each segment can be 185 meters long, which should be fine for you.
The “satelite modem” would go in the barn, along with a “server” connected to the modem. The server would also have a 10 Base 2 Ethernet card in it - you would attach that to one end of the cable you burried. The other end of your cable would be attached to another 10 Base 2 Ethernet card in a computer in your house. The “server” would need some networking software on it to act like a basic router - with some more tweaking, you could have it behave like an Internet firewall to protect your home computer.
A historical note: Thicknet (using a much thicker coaxial cable) came out first, thin Thinnet (which was also nickname Cheapnet, since the cable was so much cheaper) came out, followed by twisted-pair (10 Base T/10 Base 100, what most people use now). So, as a plus to you, if you buy a slightly older Ethernet card online, it probably has connectors for both 10 Base 2 (Thinnet) and 10 Base T (twisted pair) on it. These cards are cheap - I remember buying them on Ebay for $10 - $20 each in college.
Caveat: you will have some difficulty having more than one computer in your house on the network. You can’t “split” the cable like you can for television - the network requires the computers to be daisy-chained together. You also have to make sure to terminate the two ends of the cable with a special terminator. Also, this network is limited to 10Mb.
The only difference between thickwire and thinwire is the cable. You can actually directly connect thickwire segments to thinwire segments using only a mechanical cable connector (no electrical changes). The difference between thinwire and thickwire is that thickwire, being better insulated, has less loss and thus greater range.
It’s no guarantee that the cables already in place are 50 ohm; most TV cable is 75 ohm, which would force the use of an impedance matcher.
Also, you can use splitters on Ethernet segments as long as the splitters are bidirectional. The “daisy-chaining” that is used on thinwire is actually a T-connector in the cable; it’s not a true “daisy chain” the way it is in a token ring network. All you have to do is ensure that the impedances are balanced, which is tricky when you have splits. You could readily put as many computers as you want on the broadband segment; you just need a tap for each computer.
You don’t have to put a server with the modem. I found a few vendors that still sell 10-Base-T to 10-Base-2 and 10-Base-T to 10-Base-5 media converters; that’s all you need out there. Use another 10-Base-5 to 10-Base-T media converter at the other end, and you’ve got your Ethernet segment. (No, I did not notice prices.)
These are all primarily premise wiring types; they’re not used in wide area distribution networks (although 1000-Base-ZX has a range of 100 km). Wide area distribution networks have their own panoply of media types, which I (as a LAN engineer) have never had to deal with much.
Twisted pair ethernet can go 100 meters, which is 330 feet, so a barn 150 feet away is trivial. If you get ahold of some direct-burial cat5 or cat5e, this would be easiest. Run it from the back of the satellite receiver to the house, and plug it into whatever you want (PC, router, wireless router, etc).
However, it isn’t a great idea to run wiring between buildings unless you have the grounds tied together. That goes for your coax, too. Anything else and you are risking a lot of damage in case of a lighting strike. You want to ground the electrical systems to the same place (say, a couple of grounding rods 1/2 way in between). Call an electrician if this doesn’t make sense (and even if it does).
You can also run fiber or do this over 802.11 wireless, both of which get rid of the ground potential problem (but of course not for the coax that is already buried). Fiber will cost a bunch of money ($200+) plus tranceivers on either end ($20 on eBay), but it is the most future proof.
But Napier doesn’t want to bury another line, which is why I was suggesting going with Thinnet. And he was pondering have a server in the barn for backup anyway, so I still think my suggestion is ok.
5cent’s advice sounds good, though. You could probably get the cables grounded without having to dig the whole thing up.
rg-56 is 75 ohm, which won’t work for thinnet, which requires 50 ohm. I’m sure there are other characteristics of the cable that are different, too. Can you bodge it to work? Maybe, but why bother when 802.11 should do the trick? If range is a problem (and it shouldn’t be, 150 feet mostly outdoors is well within range), a pair of directional antennas (http://www.turnpoint.net/wireless/has.html or O'Reilly Media - Technology and Business Training or http://www.pbs.org/cringely/pulpit/pulpit20010628.html) will work, even if a mudslide separates the house and barn by a few miles.
As for grounding, the problem isn’t the coax cables themselves, it is the electrical panels. If you are the least bit unsure of this, please call an electrician! Without proper grounding, the equipment and/or you could be zapped.
Open-air optical? I’ve been wondering, but have never seen nor heard of such equipment. Who makes it???
A wireless bridge for under $100??? A bridge, of course, means both ends, so the ethernet-to-radio conversion box is less than $50? Who makes it???
In case I was unclear, having to bury another cable is solving the wrong problem. If I have to bury more cables, I’ll just bury the ones I should have had in the first place.
Will work in bridge mode, $55 each, $110 total. You could probably find it for less on eBay, because 802.11g is quickly replacing 802.11b. 150 or 200 feet really isn’t that far for wireless, and if it doesn’t work, you can throw together a directional antenna for less than $10 in parts (see the links I posted earlier).
The problem is that the cables you already have aren’t suitable for network use. I know of no off-the-shelf network that uses RG-56 (RG-58, sure, but that’s a different beast). Direct burial cat5 will work just fine for the distance that you need. You can buy 250 feet of the stuff for $50 from http://www.netnimble.net/outdoorcat5.html. You can bury it in about an hour if you have a sharp shovel. Just make a slit as deep ar you can and shove it in with a blunt object (say, backside of a wrecking bar or handle of a walking stick. Or you can rent a walk-behind trencher and get the job done in about 2 minutes.
About wireless and security… Most wireless devices (including the WAP11 I linked to) support encryption. I think the WAP11 will do 128 bit encryption. Also, you can set each bridge to only answer to the MAC of the other bridge.
Thanks for the link for the wireless bridge. I got one (well 2) recently for under $100 at the tigerdirect web site, I think they were d-link, they were for a client and really don’t recall that much about them.
I wanted to add that making the wireless bridge unidirectional in itself will help security as most of the signal will travel towards (and be absorbed by) you house and barn.
Thanks for the reference to the Linksys wireless bridge. This sounds pretty practical, in fact the most attractive option so far.
Burying another cable is much harder than you think. My soil - mostly gravel cemented together with clay - is so hard that I can’t use a shovel or even a mattock. I have to use a railroad pick (or “clay pick”). I bet I couldn’t do the job in a month. Even two-man gas powered augers don’t work, I have to drill a pilot hole with a masonry bit. So instead to dig holes I have a 400 lb PTO powered auger for the back of my diesel tractor, and I alternately drill a couple inches and then add water to the hole and let it sit and soften things up. Even that won’t go right in, even after I add extra weights, and it’s just an 8" bit. This soil even broke a backhoe once.
I did dig a trench originally, but I rented a pretty big trencher - as I remember it was about 8’ or 10’ long - and that took 5 hours of actual digging and cost about $200 in rental fees and more than one tank of gas. They didn’t charge me for the teeth that broke off. In fact, I like to think that if that job hadn’t been so exhausting I would have remembered more of the “nice to” things I wanted to add to the trench (but it still wouldn’t have been ethernet, I must admit).
Sheesh, I must have the hardest house in the US for installing broadband…
