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Wide Area Wireless on a Shoestring Budget?
wkytechhead asks: "My father owns a greenhouse operation that covers a few dozen acres. He has a number of greenhouses some up to 1000' plus apart that he would like to network. Currently he is using a HomePNA based network via regular RJ12. He has decided that he would like to go at least partially wireless. Some consideration has been given to using the backbone with fiber convertors, but he would really like to do full wireless. I have checked into homemade and commercial 'Cantennas' but I am not sure if they are worth the money. How would my fellow geeks go about wirelessly networking a large outdoor area for as cheap as possible?"
You should check out these antennas from HyperLink Technologies. For outdoor applications these should work very well for you.
Some golf courses and other large areas use remote-DSL for such links. Maybe that would apply to him? Many cisco DSL modems can be operated in server mode, only downside is you must run RJ12 separately to each location.
Otherwise, run ethernet?
if you are going to go wireless, get some good APs and sector antennas, or alternately setup a bunch of repeater stations that use different channels to avoid interference.
--IronHelix
minidishes (commonly used in the UK for digital satellite television) can be easily adapted to use a WiFi signal boosters. They're highly directiuonal of course, but ranges of 2 or more kilometers LOS are not unknown. Plus, no boosting equipment is required, just a modification to the antenna.
For outdoors, I think your SOL, but for inside the greenhouses, investigate something called "leaxy coax." It's basically a coaxial cable with little to no shielding, and a couple of companies have recently made it usuable with 802.11b/g.
Since you have greenhouses, evidently, unobstructed line-of-sight should not be a problem. I'd say, some short-range networks connected by FSO links, as per http://ronja.twibright.com/
24dBi to go 1000' is insane overkill. You could do 1000' with 5dBi
http://www.seattlewireless.net/index.cgi/AntennaHo wTo
Is a WiFi antenna howto and I build the can-waveguide out of two tomato sauce cans with an N connector. It totaled to about 5 bucks worth of parts and works very well. The tuning for it though might be off and I hand redid with a sheet metal snipper.
Unless the sites are spaced something like along a road, a mesh network would probably work and be much easier to setup as well as much more robust (I presume the network carries vital info on temperatures, greenhouse equipment status, etc).
2 2/wirelessmesh.html for an overview
See http://www.oreillynet.com/pub/a/wireless/2004/01/
Eat Lamb, 1 million coyotes can't be wrong
That inexpensive means inefficient.
I can't beleive ThinkGeek is selling dressed up Pringles cans for $45. Sickening. /. a while back too).
Go buy a can of pringles and use that. Find info here: http://www.oreillynet.com/cs/weblog/view/wlg/448
(I'm also pretty sure I saw this on
I've had great luck with a 24dBi Parabolic Antenna at over 1.5 miles away.
. htm
If all of these sites are within a mile with reasonable line of sight and not many trees in the way, I'd suggest putting the parabolic antennaes at each location directed toward your main location.
At the main location go with a nice sector antenna array.
Heres a link:
http://squitter.com/products/antennas/parabolic24
Homebrew your AP and end nodes with a workstation or soekris board and a netgate radio...or connect the antennas to commercial AP/Bridge units.
Depending on how many sites you have to link, you should get out at a reasonable cost.
This is our amateur radio repeater that uses VoIP to link to other repeaters around the world. The link is 802.11b
Here is the AP that provides access.
Nothing special to do a 1000' link. Just a parabolic grid antenna on the client side.
Here are some parabolic grid antennas.
--fatboy
Unless you have an FCC radio operators license, you may not legally perform any antenna modifications (under part 15 rules).
Pickup a WRT54G, some directional and omnidirectional antennas and get the SVEASOFT firmware.
It is quite possible, though not very easy, to do, and there are already many excellent tips posted in this thread so I will not repeat them. What nobody seems to be talking about, though, is that you have to be aware of the gotchas of any technology you are going to use. Wireless security is much different than wierd, because your adversary only needs a $50 laptop and Airsnort (so called "war driving") instead of much much more expensive hardware needed to intercept wired communication especially in a shielded medium like STP for Ethernet. The security of your systems is something that you have to design before you do anything else. You cannot just say: "I'll add security later." That's why it is important to understand how the systems in question really work. Good luck.
Sincerely,
Pan Tarhei Hosé, PhD.
"Homo sum et cogito ergo odi profanum vulgus et libido."
Buy a WRT54GS for each location, then learn about the availible wifi antennas and read their specs. Install sveasoft firmware on the routers. Purchase antennas and mounts that meet your needs. Read directions (very easy) for setting up WDS across all of your access points. With the linksys AP's, you must use antenna connectors that mate to RP-TNC (the connector type on the radio). In addition, you can use two antennas on each router. You may go for one panel and one cantenna in one location, with a single omni at another.
The first question you have to ask yourself is what you want to get out of the network. Do you want full roaming capabilities, or do you want localized points of presence in every greenhouse? Are you wanting to implement VoIP? Network aware control and monitoring systems?
If you are looking for a setup like what I had (points of presence in every greenhouse), all you need are some cheap(ish) base stations for the endpoints, and a kick ass 24dB omnidirectional antenna for the master base station at the head office. Build small networks at each pop and bango. If you want roaming in a few areas, throw in a small consumer wireless base stations and hook it up to the pop.
If, however, you are looking at using the network for business critical voice services or control and monitoring systems, then you had better look seriously at fiber (fiber ring preferably). You never know when some bird lays a massive shit on the antenna. Wireless is simply not as reliable as wired.
Feed the need: Digitaladdiction.net
very true. However some modems can be operated in reverse- buy two modems, plug one into each other and set one to be the server. Using this method you can create fairly long distance (up to 10000 feet or so) links with decent bandwidth (up to 3-5 megabits) for very little money (two DSL modems). That was the point of my submission- its cheap and easy.
--IronHelix
RadioLabs.com has an excellent selection of wireless antennas, coax, and connectors that will work for you.s s-2.html
http://www.radiolabs.com/products/wireless/wirele
Also, I agree with an earlier post suggesting the Linksys WRT54G or GS running the SveaSoft firmware.
http://www.sveasoft.com/
With a slightly better antenna and a few WRT54G's in a WDS configuration, you could easily provide both wireless and wired connections in the remote buildings and have some wireless coverage between the buildings as a bonus.
With enough of the WRT54G's in the WDS configuration and using OSPF, you could create a "self healing" component to the network.
G'Luck
No to mention that they would mostly likely be illegal to use in the US.
There is a limitation on the maximum output these FCC part 15 devices can have. With the average output of normal 802.11 devices combined with this 24 dBi gain antenna would most certainly be illegal.
There is no way I would do anything illegal in a commercial business.
That is way overkill and would be difficult to aim correctly anyway. The higher the gain the more perfect you aim has to be. And aiming at a target 1000' away is damn hard, even with laser sights.
Hard to answer without understanding how its used. Maybe he wants to browse with his latop anywhere on his land. Or maybe he has sophisticated and critical monitoring and control of his greenhouse operations run by this.p hp) near the centre of his land with a high gain omnidirectional antenna should give pretty impressive range. If his property is say 50 acres square then thats 0.5km on a side, so not really that far. The only question then is does that provide enough signal strength to be directly received by comodity embeded antennas or will each greenhouse need a directional antenna pointing at the omni on the mast. I'm not sure at what point the FCC would regulate mast height for an ISM band.
Regardless, my first approach is try what is simple. I presume its reasonably flat and obsticle free land. A simple, adequately tall mast (http://www.hyperlinktech.com/web/antenna_height.
In a few years if this is the low bandwidth control application I imgine it really is then it might be solved by a zigbee mesh solution at very low cost and maintainance.
Or you can search froogle for them
"2.4 ghz parabolic antenna"
Lowest price is around 33$ for a 15dbi gain. 50$ is about right for a 24dbi gain. Though a parabolic is only going to be truly handy for sight to sight. They do have low cost omni directional antennas. This is difficult to advise without knowing the layout.
ie, possibly sight to sight parabolic for the backbone link and then omni's distributed throughout.
If you are really worried about distance, just dig up a router that can be tweaked for a bit more output power.
Now, if completely unsure of what your needs are, here is a handy calculator to help you figure your distance needs out.
http://www.signull.com/fsc.php
For the uninformed, cable loss is going to be calculated by the amount of signal loss expected when using some portion of cable from the transciever to the antenna. It should be expressed quite clearly on type of cable you are going to be using.
There are also some common models output numbers listed there as well.
That really sums up everything. It should be quite cost effective to implement a few antennas and a cheap 802.11b setup.
"You should always go to other people's funerals; otherwise, they won't come to yours." -- Yogi Berra
Parkervision http://www.parkervision.com/ has an access point with standard antennas that when used with it's cards has a 1 Mile open field range. Since a farm should be pretty open field, 1000 feet should not be a problem. They have a money back guarantee if not satisfied. They used 1 AP to cover an entire small airport in Florida, see http://www.parkervision.com/company/press_room/new s_by_id.php?id=126
I don't know where your're buying those from, but I got mine for $50 USD.
Pretty Pictures!
This is discussed a lot over on ISP-Lists - you'll probally find this page very helpful. The guy who wrote it is a guru in homebrew type services - dsl and wireless.
So, the limit is 30 dbm (1000 milliwatts), most wireless cards are about 15dbm, which gives us 15 dbm of slack. 24dbi exceeds 6 dbi by 18, so this would be illegal for a point-to-multipoint topology. However, if it was a point-to-point link, that 18dbi of excess gain results in a reduction of only 6dbm of permitted power, so you could use a 24dbm radio (or a little over 200mw) legally. (Though ianal or an rf engineer, so take this with a grain of salt.)
Try this simple and trusted design of the good ol' spider omni http://flakey.info/antenna/omni/quarter/. Been using it a lot and will extend an AP's range to between 300 and 500 metres (that's around 900 to 1,200 feet).At the Bristol Wireless project we've used them on roof-tops to hop from point to point in a mesh network, I'd imagine it'd work just as well for greenhouses.
At that distance, regular old 802.11 will be fine. Two $50 directionals, use a of the shelf AP at one end and an off the shelf network card at the other. Keep the cable runs short. Long cable runs mean you need rather expensive cable. If you're unable to place the PC with the wireless card close to the antenna, use a Pentium class throwaway stuffed in the attic to bridge it to Ethernet, or a second AP. (Make sure the two AP will interoperate without too much firmware headache.)
You should be able to deal with minor tree obstruction.
.sig: Now legally binding!
www.smartbridges.com
the all in one units.
simple. cheap.
Forget about conduit. I used 3 pair direct burial phone cable. One pair for the network running at 2.3Mb/s and two phone extensions about 1200 feet to my workshop from the main house. An ethernet extender is used to at each end. You'd need a cable and a pair of extenders to each greenhouse from the central location. Wireless is nowhere near as reliable and secure if you can run a wire and most likely cheaper also. Use wireless ONLY if you cannot reasonably bury a cable.
All theory is gray
Use a link budget calculator. (The link is one I just found with google).
Basically, you need a certain signal to noise ratio for a digital radio connection to work at all at its lowest speed. Increased signal to noise ratios get you more speed and some margin of reliability.
Signal decreases with the square of the distance. If you double the distance you'll have one quarter the signal, or 6db less (decibels are logarithmic - 3db is a ratio of 2, 10db is a ratio of 10). So, everything else being equal, you'd need 6db more gain on the antenna at either end to get the same results.
For your particular scenario you'd probably be fine with just a couple cantennas or other moderate-gain antennas.
One thing to watch out for when shooting through trees is that they may not have leaves now but they will in a few months!
Most Access Points put out a measly 15mW. Some will get you 35mW. What you need is a decent antenna combined with a more powerful radio card.
http://estore.itmm.ca/ has many models of 200mW access points.
From what I've heard, the best policy is to stick to lower-gain omnis for local base stations and use dishes for any long range links.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
This is a greenhouse environment.
A lot of those wireless cable antenna are actually in the 2.5ghz range.
Still, they will work just fine, with some gain loss...
Here is a smaller article on the matter... to adapt one. (kinda helpful if you really really don't know what you are doing)
http://www.qsl.net/n9zia/wireless/page04.html
"You should always go to other people's funerals; otherwise, they won't come to yours." -- Yogi Berra
The greenhouses are grouped into clusters, for example there is a 1000' gap between our Annual houses and our Retail houses. Then there is a 500' gap between those and other buildings, etc. The offices are about 1500' away from the retail and 500' away from them is my parent's house.
/. no matter where we are at on the farm, ;)
We want to be able to access via laptop current production request, orders, etc from anywhere on the site. Also we want to be able to control climate from any location on the property.
Other applications are webcams for us to watch employees, and so forth. The biggest issue is climate control.
As far as humitdity it will play a part, this is the reason for using cheap laptops instead of setting a PC at each location, etc. We can use a few centralized pcs with plc interfaces to montior tempatures in climate controlled cabinets.
And of course the most important thing is to be able to surf
You could get a mesh network up and running without too much cost. If you invest on 3-4 Linksys WRT54(g) devices and run something like http://www.olsr.org/ on them, then you have a running mesh network.
I would recommend that you purchase a BOOK.
Wireless LAN's End to End
and
Wireless Networks The Definitive Guide
are both excellent books that clearly explain the issues involved with DESIGNING a wireless network.
A +24dbi parabolic dish is more than innappropriate for what you are doing, so is running firmware hacks to "Pump Up Your Power".
It's not about how much signal you can irradiate the land with, it's about placement and antennae with the correct signal pattern.
Here are a few links that I found while googling around. They should be of some help.
Quite a few Wireless Network Links
Long Distance Wireless Network Project
Wireless Network Security Article
Forum discussion concerning long range wireless routers