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Wireless Networking Hardware Hacking Hardware

Wide Area Wireless on a Shoestring Budget? 239

Posted by Cliff from the cheap-area-networking dept.
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?"
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Wide Area Wireless on a Shoestring Budget? More

Wide Area Wireless on a Shoestring Budget?

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  • 24dBi Point To Point Antennas for around $55 each (Score:5, Informative)

    by codermarc ( 774934 ) * on Thursday February 03, 2005 @07:07PM (#11567630) Homepage
    You should check out these antennas [hyperlinktech.com] from HyperLink Technologies. For outdoor applications these should work very well for you.

    • Re:24dBi Point To Point Antennas for around $55 ea (Score:2, Informative)

      by Anonymous Coward
      24dBi to go 1000' is insane overkill. You could do 1000' with 5dBi
      • I've never understood the whole dBi to range conversion. I know it's not direct, but how do you figure it out? I'm going to try and put up a link between my parent's store and their house, a distance of just under half a mile. The house sits up on a hill, and I think I can get a straight shot from the roof of one building to the roof of the other. There might be a tree or two in the way. What should I expect to use? What problems will I encounter?

        • Re:24dBi Point To Point Antennas for around $55 ea (Score:4, Informative)

          by technos ( 73414 ) on Thursday February 03, 2005 @08:57PM (#11568459) Homepage Journal
          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.

        • Re:24dBi Point To Point Antennas for around $55 ea (Score:5, Informative)

          by rcw-home ( 122017 ) on Thursday February 03, 2005 @09:14PM (#11568579)
          how do you figure it out?

          Use a link budget calculator [ecommwireless.com]. (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!

    • I've used those. They work good but they're a little unwieldy, and probably overkill in this case. (I used a pair of 24dbi parabolics once to test a 5 mile link. It worked, but thoughput wasn't great. In retrospect, the link may have been degraded by the tinting of the window I was transmitting through at one end.)

      I've also used panel antennas from superpass [superpass.com], many of which have smaller sidelobes than the parabolics, and are smaller and (usually) cheaper.

      At 1000', you might not even need directional

    • Re:24dBi Point To Point Antennas for around $55 ea (Score:5, Informative)

      by Cylix ( 55374 ) * on Thursday February 03, 2005 @07:57PM (#11567997) Homepage Journal
      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.
    • Those antennas do work pretty well, but I suggest keeping their return policy in mind. Or rather, their don't return policy. HyperLink doesn't accept returns except for exchanges on defective equipment. Maybe they changed their policy, but read it first.

      You are stuck if you order the wrong one. I nearly got burned buying from them. I never did get the lightning arrestors to work properly, they just degraded range and signal quality unacceptably for reasons I can't figure out.
    • 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.

  • DSL (Score:5, Informative)

    by Helix150 ( 177049 ) on Thursday February 03, 2005 @07:08PM (#11567631)
    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.
    • This is some damn good advice here. Especially since the questions asker alredy specified he has existing rj12. IIRC these these DSL modems are very cheap.
      • DSL modems are cheap; DSLAMs [google.com] (the other end) are NOT.

        • Re:unfortunately, (Score:3, Informative)

          by Helix150 ( 177049 ) *
          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.
          • whoa. What 2 modems have you tried? and how well does did it work?

            • Re:unfortunately, (Score:3, Interesting)

              by Cylix ( 55374 ) *
              This isn't a new concept.

              In fact, you can attempt to order an alarm circuit or dry copper pair from your telephone company. If you manage to get it and they don't have a filter in place you can slap on two dsl modems for a low cost high speed leased line.

              I've had co-workers buy their telco guys beers to have the filter removed.
              • With ISDN. Lots of folks did it.

                This is the first time I've heard that it was possible with DSL. Please give us more details.

                You could also buy a DSLAM. I've got a used CopperEdge I'd like to get rid of. 24 IDSL ports and 24 SDSL ports, routeable from the ethernet jack on the front.

            • Re:unfortunately, (Score:2, Informative)

              by selfabuse ( 681350 )
              This is discussed a lot over on ISP-Lists - you'll probally find this page [odessaoffice.com] very helpful. The guy who wrote it is a guru in homebrew type services - dsl and wireless.
    • What the hell? And just how many boxen would that take? I think he wants the version wtih 15 antennas and 1 computer, not 15 computers and wires coming out his ass.

      Thanks for trying though.

      My guess is he wants 1 box and 2-5 BIGASS antennas to just swath his plants with radio waves.

      Or maybe he wants to see someone's crazy hack of some sweet ass 5 foot antenna that looks like an x-wing and has 5 miles of range.

      • Re:DSL (Score:3, Informative)

        by Helix150 ( 177049 ) *
        you're welcome!

        this by no means requires any computers at all. I saw an article a while ago about a golf course that did this- they had a shelf of 8 $89.95 Cisco DSL modems (all set in 'server' mode) at their datacenter, linking to offsite signs around the course. Each sign had another dsl modem, operating normally. The only wiring they did was to run each sign a dry pair, and plug the modem to the sign's Ethernet controller.

    • Re:DSL (Score:4, Interesting)

      by DrZaius ( 6588 ) <gary.richardson+slashdot@gmail.com> on Thursday February 03, 2005 @08:01PM (#11568024) Homepage
      You might also want to check out Ebay for some Cisco LRE [cisco.com] stuff. There was a video floating around where John Chambers was doing video conferencing with LRE over speaker wire, phone wire, barbed wire and a wire fence -- the really impressive part was that it was 2 or 3 times longer than the max recommended distance.

      out.

  • Minidishes (Score:5, Informative)

    by EdZ ( 755139 ) on Thursday February 03, 2005 @07:08PM (#11567636)
    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.
  • but it sounds like a great use for a mesh networking.

    • Re:no necessarily cheap (Score:5, Informative)

      by billhuey ( 183070 ) on Thursday February 03, 2005 @07:12PM (#11567679) Homepage
      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.

      • How about this:

        http://www.belkin.com/networking/

        Belkin's Pre-N Wireless supposedly has 800% wider coverage and is totally affordable. It might not be what the stand ends up being in the future, but hey, as a totally proprietary system it looks to kick butt!

    • Re:no necessarily cheap (Score:3, Interesting)

      by mnmn ( 145599 )
      I agree.

      Since you own all the pieces, and the traffic isnt high unless you plan to stream videos from your plants, go wireless mesh. Properly setup, this would actually be a more robust setup.

      I wonder if you could also do a whole bunch of p2p connections and run BGPv4 over it. Will look great over your resume.
    • 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).

      See http://www.oreillynet.com/pub/a/wireless/2004/01/2 2/wirelessmesh.html [oreillynet.com] for an overview

  • That's not going to be easy (Score:5, Informative)

    by spawnofbill ( 757153 ) on Thursday February 03, 2005 @07:09PM (#11567645)
    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.

    • Re:That's not going to be easy (Score:4, Informative)

      by Anonymous Coward on Thursday February 03, 2005 @07:15PM (#11567708)
      I observed leaky coax tests at a previous company, and it didn't seem to work very well. It seemed to work for the AP transmit, but the return signal was week (imagine, the signal recieved at the far end of the leaky coax, it is leaked all the way back to the AP).

  • Cows (Score:5, Funny)

    by Anonymous Coward on Thursday February 03, 2005 @07:09PM (#11567649)
    Wire cheap antennas to cows.

    Problem solved :)

  • sounds like a plan... (Score:3, Funny)

    by Haydn Fenton ( 752330 ) <no.spam.for.haydn@gmail.com> on Thursday February 03, 2005 @07:10PM (#11567656)
    1. use greenhouses for greenhouse-like things 2. ??? 3. profit! 4. buy dedicated satellite

  • building your network (Score:4, Funny)

    by Mr. Falco ( 856087 ) on Thursday February 03, 2005 @07:10PM (#11567663)
    I would find the central point and place broadcast point there and at the end of that one range place 2 at the other points to max. range and give full coverage. Nice idea. I am working on something like that for my wine cellar.

  • WDS (Score:2, Insightful)

    by Leroy_Brown242 ( 683141 )
    Just buy a grip of WRT54G APs, get your choice of custom firmware, turn up the wattage a tad, and use WDS.

    Then, spread them evenly. I'm sure it'd work famously.

  • 1000' = No Problem (Score:3, Informative)

    by pgp4privacy ( 656621 ) <pgp4privacy@gmail.com> on Thursday February 03, 2005 @07:17PM (#11567724)
    I've had great luck with a 24dBi Parabolic Antenna at over 1.5 miles away.

    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. htm

    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.
    • I presently have a wireless link spanning five and a half miles between two sites. We've got pretty good line-of-site, with only the tops of a few trees, and two highway overpasses sticking up into the fresnel zone, but it works mostly well 99% of the time except when the weather is really bad. At one end, there is a Linksys WET11 connected to a 24 dBi parabolic grid antenna on a 30' pole. The other end has a 12dBi omni antenna on a short pole above a rooftop connected to an old WAP11 access point.

      Visit F [fab-corp.com]

  • This is what I use for a 1000' link (Score:5, Informative)

    by fatboy ( 6851 ) * on Thursday February 03, 2005 @07:18PM (#11567728)
    This is our amateur radio repeater that uses VoIP to link to other repeaters around the world. The link is 802.11b [groovin.net]

    Here is the AP that provides access. [groovin.net]

    Nothing special to do a 1000' link. Just a parabolic grid antenna on the client side.

    Here [fab-corp.com] are some parabolic grid antennas.

  • WRT54G (Score:3, Informative)

    by jsimon12 ( 207119 ) on Thursday February 03, 2005 @07:18PM (#11567731) Homepage
    Pickup a WRT54G, some directional and omnidirectional antennas and get the SVEASOFT firmware. [sveasoft.com]

  • Try waveguides (Score:2, Interesting)

    by S-D-Guy ( 856197 )
    www.trevormarshall.com/waveguides.htm He explains the how and why, so you cab build a 180 degree waveguide.

  • Possible (Score:2, Informative)

    by Pan T. Hose ( 707794 )
    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 [schneier.com] 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 [sf.net] (so called "war driving [theregister.co.uk]") instead of much much more expensive hardware needed to intercept wired communication especially in a shie
    • instead of much much more expensive hardware needed to intercept wired communication especially in a shielded medium like STP for Ethernet

      Surely if the cable runs are 1000' over fields between greenhouses, the only equipment needed to intercept would be a pair of snips and a crimper?

  • maximizing coverage with the right antennas (Score:5, Interesting)

    by ubiquitin ( 28396 ) * on Thursday February 03, 2005 @07:26PM (#11567791) Homepage Journal
    Cantennas are the wrong way to go, as their propagation pattern approximates linear, like the yagi designs. What you want is an omni, sometimes called marine, antenna that will spread signal in a plane. If you're in a greenhouse, I'm assuming you don't want strong signal going up or down, but horizontal in the plane of people walking around. Here's an example of one I grabbed from Google: radiolabs omni antenna [radiolabs.com] For about another $30 you can pick up pigtails on eBay that let you attach these to the usual netgear/buffalo/d-link/linksys/etc. accesspoints. You can place them for effective 10Mbit coverage about one for every 2 acres assuming clean line of sight to the antennas and no major obstacles. Note that vegetation would definitely impact signal propagation in the 5.4ghz band.
  • At my place of work, we have a wireless backbone that links over 16 miles. When one of our primary units went down due to a lightning problem, we constructed a cantenna and pointed it at the remote ap. The backbone was linked up once again and it worked great! We eventually replaced the redundant link with a 24dbi parabolic, but it's worth the small amount of time to check out the cantenna solution, as it's significantly cheaper than the parabolics.

  • The cheapest way, wireless repeaters every 100' (Score:3, Funny)

    by Anonymous Cowherd X ( 850136 ) on Thursday February 03, 2005 @07:29PM (#11567811) Journal
    I would have workers every 100' and they would throw packets back and forth. The workers would not need to know TCP/IP since they would not even need to operate at Level 1, they would just act as repeaters/fowarders, only needing to know whether to throw a packet to the next or to the previous worker and that would be easy because they would just have to make sure not to return the packet to the worker they got it from. This repeater/forwarding mechanism works well and requires no additional expenses since the workers would be hired to do actual work in the garden anyway. Oh and did I mention the workers are wireless as well?

  • RFC 1149 (Score:5, Funny)

    by teval ( 683486 ) on Thursday February 03, 2005 @07:34PM (#11567855)
    Can't get much cheaper. http://www.faqs.org/rfcs/rfc1149.html

  • Its simple, really (Score:2, Informative)

    by Anonymous Coward
    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 si

  • http://shopping.netsuite.com/s.nl/c.403468/sc.5/c a tegory.35/.f [netsuite.com]

    Three levels of gain - 15, 19, and the highest being a very respectable 24dbi. That would probably be overkill for your use - just placing the 15dbi gain one up on each end and aiming them properly should give you an excellent signal point to point. They're fully weatherproof too, unlike the "pringles can" jobbies, and they're actually reasonably priced. The 24 is under $70 iirc and you don't have to buy a pigtail. (cantenna pigtails cos
  • 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.

    • The trouble with super-duper omnidirectional antennas is that the horizontal beam is extremely narrow, particularly at short ranges. That makes them very flaky.

      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.

  • A RadioLabs and Linksys solution (Score:3, Informative)

    by p38 ( 807402 ) on Thursday February 03, 2005 @07:50PM (#11567960)
    RadioLabs.com has an excellent selection of wireless antennas, coax, and connectors that will work for you.
    http://www.radiolabs.com/products/wireless/wireles s-2.html [radiolabs.com]

    Also, I agree with an earlier post suggesting the Linksys WRT54G or GS running the SveaSoft firmware.
    http://www.sveasoft.com/ [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

  • Keep it simple (Score:2, Informative)

    by Ion Berkley ( 35404 )
    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.
    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. p hp) near the centre of his land with a high gain omnidirectional antenna should give pretty impressive
  • Parkervision http://www.parkervision.com/ [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 [parkervision.com]
  • Will a powerline networking signal travel 1000'? If all the buildings have electrical, that would be more secure than wireless.

    If money is no limit, run fiber-optic and bury it deep...
  • Wifi has lots of issues with interference. It shares bandwidth with cordless telephones, microwave ovens, and too many other similar devices to name.

    Also, wifi is short range - directional antennas are at best a partial solution, and aren't much easier in many cases than running cat5.

    You never specified the actual problem you're trying to solve. You already have telephone wires going to the greenhouses, what is wrong with your existing setup? Speed? Connection problems?

    Or is it just plain "Geek factor"

  • Sumatrabucks (Score:4, Funny)

    by MorboNixon ( 130386 ) * on Thursday February 03, 2005 @08:20PM (#11568183)
    Just convince the city to run two perpendicular streets through your property. The resulting intersection will produce no fewer than 4 Starbucks coffee shops, each with their own wi-fi transmitter. Problem solved.
  • First off determine if wireless is really what you want. Write down, then price out scenarios, keep in mind every few months you don't do this the prices drop and the products improve.
    1. I reccomend buying a few Linksys WRT54GS boxes for getting your feet wet. They're ~US$50. Don't cheap out and buy the WRT54G's for a few bucks less as the GS has a bit more flash memory you might want a year or two down the road.
    2. Download the free Sveasoft [sveasoft.com] firmware, or any of the other distribs out there. Sveasoft is due fo
  • If HomePNA is working well as a "backbone", why change it. Just add wireless AP's coming off the HomePNA where you want to have wireless access.

    Actually that is what I do in my home. WiFi couldn't get everywhere so since I had some HomePNA cards around, I just created a HomePNA long distance link with a couple of WiFi nodes at the ends.

  • The old spider omni (Score:3, Informative)

    by adelayde ( 185757 ) on Thursday February 03, 2005 @08:57PM (#11568453) Homepage

    Try this simple and trusted design of the good ol' spider omni http://flakey.info/antenna/omni/quarter/ [flakey.info]. 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 [bristolwireless.net] 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.

  • If you don't mind some extra work per node LocustWorld [locustworld.com]'s MeshAP sofware (Linux-based) runs on 266Mhz PCs with 64Mb RAM. You can "flash" an old 2G hard drive with the software. Such old systems can usually be had for around $40. An 802.11b PCI card runs $30. Pigtail $20. LMR400 cable to reach outside and to the roof maybe $40. A 9dbi omni antenna about $50.

    $180/node.

    You can install SIP for VoIP if you want.

  • Smartbridges (Score:3, Informative)

    by BawbBitchen ( 456931 ) on Thursday February 03, 2005 @09:07PM (#11568534) Homepage
    www.smartbridges.com

    the all in one units.

    simple. cheap.
    • Smartbridges are horrible in noisy wireless enviroments FYI. But they are decent for what he wants them for, where no other wireless equipment is operating.
  • Use 802.11 or wired networking within each greenhouse with bridges between.

    The bridges can be a variety of technologies depending on the needs and setup. Visible light / infrared / laser repeaters are pretty good for line of sight apps but have problems in extremely severe weather.

    The cantennas are a good choice. From all accounts homemade can be as good as commercial easily, if you build them with precision. Just use wired to 802.11 bridges, set each bridge to a different channel. If you use wireless
  • 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/ [estore.itmm.ca] has many models of 200mW access points.

  • I'm missing something... (Score:3, Insightful)

    by pi_rules ( 123171 ) * on Thursday February 03, 2005 @10:08PM (#11568908)
    I grew up in a greenhouse as my parents own one. For the life of me I cannot imagine why you'd need fairly high speed 'net access across buildings, unless you have offices that are scattered about the property. Not sure why somebody would do that though.

    I also can't figure out why you'd have a 1000' foot gap between buildings... unless you're mostly doing nursery. If that's the case then all the chaps saying to go wired would probably re-think their stance. You don't want to bury wire in a field that's getting replanted with nursery on a regular basis. Of course, you've already got phone lines down there, so, like the title says: I'm missing something.

    Something that I haven't seen addressed are the CONDITIONS that this equipment will have to operate and survive in. At best you're dealing with very humid. Depending on the setup you might also be dealing with very hot. When the stock is gone and its summer time a greenhouse gets HOT around here -- 110 degrees or so on some days. I think I've seen 120 once or twice while in there. Dust gets everywhere if you're using any sort of automated filling or soil mixing system which given your size I'd imagine you are. Although then again I go back to the "mostly nursery" idea and it changes.

    For the non-greenhouse geeks in the house nursery (perennial plants) are typically grown in regular black-dirt top soil. The kind of dirt you'd find in your yard. Potted annual plants are grown in a mixture that largely consists of peat moss and that stuff flies FOREVER when its dry, which it is during mixing or filling of containers.

    So.. 90% humidity, 75 degrees, dust flying everywhere... will a LinkSys WAP with an external antenae hold up to that? Don't ask me, I'm just a "farm boy" :)

    I'm still VERY curious as to why you need/want more throughput then you already have. I'm not saying your crazy or anything, I'm just really wondering what I've missed in greenhouse technology. Seems to me if you're doing any sort of data collection with a roaming handheld you could just want until you cradled the device for a data download. I can't imagine anything that would need to be real time except for outside temp, a number of inside temp monitors, outside wind, sun conditions, etc. ... and all that fits nicely over even a 9600 baud serial connection.
    • 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.

      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
  • Bring a ladder to the nearest college campus and tell them your doing repairs.
  • If you really want distance, get an antenna with a very small beam width.

    I have two WiFi antennas. A homemade cantenna I built using these instructions. [turnpoint.net] I've experimented with adding a funnel [seattlewireless.net] with limited success.

    I get pretty good distance with it (big improvement over standard Omni that came with my D-Link 802.11b card, but nothing like what I get using my parabolic grid antenna. [sharperconcepts.net] It's about $50 after shipping, but the 15 degree beam width is worth it over the 35-50 degree beam width you'll get out of a h

  • Sveasoft (Score:2, Interesting)

    by docubot ( 708753 )
    I can't believe that nobody has mentioned Sveasoft [sveasoft.com] yet.

    Linksys Access Points are based on linux and they opened up the firmware under the GPL. Several groups have released modified firmware, Sveasoft is just one of them.

    I have 2 linksys WRT54G access points in my house. Only one of them is plugged in to the cable modem. The other connects back wirelessly over WDS. I can connect to the internet from either of them.

    One of the best things things is that they allow you to crank up the transmit power.

    If

  • You don't say what kind of data he's passing around. Is he actually connecting PCs together, or is this like temperature & humidity data?
    For the former, you're on the righ track. For the latter, there are any number of potential solutions that can't be decided on without more information.

  • How about multi-hop? (Score:2, Informative)

    by cibus ( 670787 )
    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/ [olsr.org] on them, then you have a running mesh network.
  • Ok, a dish is a high-gain antenna. Is it because the antenna magically produces energy from nothing and amplifies the signal? No.

    Gain comes at a price.

    The only way an antenna can produce gain, is, by limiting the directions in which it is effective.

    A longer dipole (vertically mounted) becomes less effective in the vertical range - which means a long dipole that is perfectly vertical will not really transmit a lot of the energy upwards (and will therefore suck for satellite communication - which you don't

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