Wireless DATA Link 27
Gepeto_42 writes "Somebody asked me to help him find a way to get a data link from the coast to a little island where he's gonna have his business (I can't give too much details, it's still secret). The island is at about 10kms from the coast. Is there something else than HAM that could work? Micro-wave? It's in Quebec, Canada, by the way." Probably the best solution would be the 802.11 wireless LAN cards with a souped-up antenna - I'm pretty sure that people have made these work farther than 10km.
Cisco Aironet works great... (Score:1)
LMDS (Score:2)
HAM? (Score:2)
In most countries, you can't use amateur radio for commercial purposes.
As other posters have suggested, your best bet is a point-to-point microwave relay. Talk to a local communications engineer about cost, licensing, bit rate and link margins. There are many prepackaged digital microwave systems available today.
Re:What about lasers? (Score:2)
don't forget latency (Score:3)
anything that is satellite based will add quite a bit of latency (what i've heard is about 400ms each way).
802.11 is pretty much out of the question. it's slower than microwave, and has the distance problem. large signal amplifiers could probably make it work, but i doubt it would be very robust at that distance. 802.11 also decreases in overall bandwidth the more distance between nodes.
microwave technology can go about 30 miles, and has pretty low latency. you'll need some land on the mainland (rent tower space) to put a microwave dish, and another tower on your island (or whatever it is). i've setup and used one-way microwave connections, and they're suprisingly fast (i was about 15 miles from the tower). microwave is also good for cooking passing birds, but that's a different story.
if you'd like to read a little up on this technology, www.thebeam.com sells commercial and residental microwave packages. most of them include tv also. i don't work for them, i just admire their technology.
802.11 (Score:1)
I've used 802.11 only for shorter distances, but have reports, that using (good) yagi and parabolic antennas is working for 15 km.
But you need a direct line of sight, with absolutly no abstacles. And keep the koax-cable to the antennas as short as possible!
Furthermore, most 802.11 equipment is available in an european and an american version. The american version has up to 5times more power.
bye, Adrian
Proxim Stratum (Score:1)
"The Stratum 100 and Stratum 20 are point-to-point transparent MAC layer bridges which provide full duplex 100bT connections over links up to seven miles (11.2 km)."
"The Stratum MP is a multipoint learning bridge which provides half duplex 10bT connections to multiple facilities over links up to 12 miles under FCC rules, and over 5 km under ETSI rules."
I used to do some contract work for WaveSpan [wavespan.com], the guys who developed these and got bought by Proxim.
What about lasers? (Score:1)
try freewave.com DGVRO-19 transceivers (Score:1)
25 miles (Score:2)
http://www.precept.com/univercd/cc/td/doc/pcat/ao
Its on the internet so it must be true.
Microwave.. yep (Score:2)
You are however going to need a tower on both
sides. Its not gonng be cheap but I have seen ads
for 45 mbit microwave setups. 10km is not a distance you want to try to hack together with
things like 802.11B cards. If this is a buisness
then they should be buying commercial grade products.
Re:Will it really cook passing birds? (Score:3)
http://www.wirelessmountain.com/superl inkspecs2.html [wirelessmountain.com]
It's a 10baseT microwave link that will do 15 km with an output power of a whole 50 watts. My 1200 watt microwave might be sufficient to cook a very small bird in a minute, but 4% of that power isn't likely to do much.
A back-of-envelope calculation suggests that even if a small bird like a grashopper sparrow [state.ct.us] were to absorb 100% of the power of this beam and was perfectly insulated by its feathers, it would heat up by about 0.7 deg C per second. That's slow enough that it certainly won't cook a bird flying through the beam; the bird would somehow have to perch right in the beam and stubbonly stay there despite feeling uncomfortably hot. Oh, and when it passed out it would have to somehow stay in the beam to actually get to cooking temperatures.
And of course in real life, the bird won't absorb anything near 100% of the power, and would lose a lot of the gained heat to the air around it. So if the original querent sets up one of these microwave links, he should plan to keep getting his fried chicken the usual way.
Hmm... (Score:2)
And, after IC finds out, and the RCMP breaks down your door and confiscates your equipment, tell them that the one armed man made you do it. =)
Note that, with the EIRP limits typical of radiated power regulation, even extra gain due solely to antenna modification is cause for concern.
smugglers need networking? (Score:1)
well, sooner or later Cisco will cook up a CCNP or IE test for it then... ("Q1010: When attempting to establish an access-list on a 25xx router while under fire from customs...").
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Options (Score:2)
You could use a commercial wireless data provider. If nothing else has coverage, some of the satellite networks should be there.
You could run a Aironet (Cisco now) wireless bridge. My guess is that this would cost about $5,000 (USD) for the 2 bridges and antennas. These things are sweet though. They're even a cost-effective alternative to a wired connection across town.
There's always microwave, with the licensing hassles and cost.
For the low-speed route, you can do something close to what hams use. A number of companies (like Paccomm http://www.paccomm.com [paccomm.com]) sell commercial (non-amateur) wireless data modems. You can hang a pair of these on a VHF or UHF frequency and do at least 2400 bps.
What Speed? (Score:4)
The most important piece of the puzzle was left off of this question. At what speed is the connectivity needed? Another question would be what level of reliablity.
First of all, let me qualify the following information with the fact that water changes things. A lot. Especially at frequencies up in the ghz, where water is essentially a mirror. That said, running a link across this much water isn't impossible, it just takes some engineering work.
The first piece of information I want to provide is that you can do a 2.4ghz 802.11b link at 11mhz over this distance with the right antenna system without even breaking a sweat. There is sufficient link margin for 99.99+% uptime. I have links running over 20 miles without any problems at all. You should also have almost no interference problems in the environment I envision. Again water will be an issue, but you should be able to work around that. This would provide a 11mb/s radio rate (About 5-8mb/s usable) link. This would be cheap. About $2000 an end when you get done putting together all the pieces. Towers not included.
Using different equipment, I can go up to 15 miles (24 km) at 93Mb/s. Assuming this is 10km or less, I can also go up to 7 miles (11km) at 420Mb/s (Full Duplex, 840mb/s aggregate). Of course these are much much much more expensive.
All of the above options are license-exempt, which basically means that at least in the US you don't need a license. I think that Canada is in the same boat, but I would have to do some more research. There are also licensed options.
To hopefully drive home the point above. You need to find someone qualified to do the engineering on this. It is NOT as easy as it looks. I find that most "experts" on this either are in the category of "I've done a couple of these and they work" or "I couldn't make them work". You need to find someone who understands the inner workings of why these work or don't. If they don't know about path loss calculations, freznel zones, etc. etc. etc. then they're probably not going to be any good to you.
I normally don't try to market my services when I post. However, if you can't find someone you feel is qualified or if you'd like me to look over someone elses design, drop me an email.
Re:don't forget latency (Score:1)
That's if the satellite you're using is in geosynchronous orbit, and in that case the one-way delay is @250 ms, assuming the satellite is essentially a repeater (i.e. no delay introduced on the satellite itself). Some of the newer satellite systems use low-earth-orbit sats, and for them the latency is much better.
Re:don't forget latency (Score:1)
The question says 10Km. That's not a long distance. Speed-of-light delay at 10Km is about 30 microseconds. It's about that far from my house to Yahoo and I can get there and back in 8ms. At least I can today; we'll see what happens when they throw the big switch at Northpoint on Monday.
3000 or so miles across the country is a long distance. That's about 20 milliseconds absolute mininum speed-of-light delay. In reality, I see about 70-80ms delay in between two IP hops cross-country (San Francisco to Reston, for example).
More info about latency vs 802.11 (Score:1)
It appears that there is an issue here, but it's an 802.11 issue, not an IP issue as I'd assumed the poster was implying. See here [slashdot.org] for a subsequent SlashDot article by someone else talking about the need for less than 20usec latency in 802.11, which would be in the 1-2 mile range.
Re:Will it really cook passing birds? (Score:1)
Just consider the power in your home microwave. It can cook birds easily if they stay there for a minute. Now think about how if it's going to be able transmit 10 km...
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Re:Will it really cook passing birds? (Score:2)
Who said it would cook the bird just if it was just flying by anyhow? It'd have to sit there or something...
I can't be karma whoring - I've already hit 50!
Re:Possible? (Score:1)
Um, security? (Score:2)
There are a multitude of systems for inter-building and inter-campus bridging, all of which will get you significant bandwidth. Some use microwave technologies, other use lasers. I'm not aware of how much curvature of the earth takes place over 10 KM, or how tall a tower you may be able to build to see over the horizon, but I would definitely look there. One more thing, also security-related: physically secure the land-side of your connection, as it's a perfect place to just hook up a laptop and sniff like the dickens.
No, you will NOT cook birds - can't cook a gnat. (Score:1)
FWIW, if the range is 10 miles that page says you could expect 11 Mb/sec out of the Ciscos.
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Security, amateur radio, tower height (Score:2)
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Possible? (Score:1)
Re:Cisco Aironet works great... (Score:2)
Quoting Cisco, the Cisco Aironet 340 Series Direct Sequence Ethernet Bridge... :
This looks like what you should get mainly because their is no real hacking that is needed. Yes this takes away the fun but Cisco is designed for the distance. I would recommend checking EBAY [ebay.com] for some good prices. Remember that you will need two of these if you plan to have a wired network on this "island" of yours... But if you don't: just get one base for the mainland and then a pcmcia card for the island (cheaper that 2 base stations).
I hope this helps!