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Hardware

Wireless Serial Adapters 33

Posted by timothy from the buy-back-those-homing-pigeons dept.
Foxxz writes: "I was looking for a wireless solution to link 2 PCs wirelessly at a short distance (less than 300 ft). I thought about wireless NICs but decided they would cost too much and provide more speed than needed. Alternatively, I began searching for wireless serial adapters thinking they may provide a cheaper solution but found surprisingly most were more expensive. Is there a cheaper way to go wireless?"
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Wireless Serial Adapters More

Wireless Serial Adapters

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  • IRDA (Score:1)

    by Anonymous Coward
    dont invent new stuff..just use the unused IRDA ports on your machines.

  • Google is your friend (Score:1)

    by Anonymous Coward
    All you ever need at more: Google Search for sneakernet [google.com]

  • Wireless modems? (Score:4)

    by crisco ( 4669 ) on Sunday July 22, 2001 @10:45PM (#68024) Homepage
    Years back we looked at some wireless modems of some kind but it was so long ago that I haven't a clue as to what they were. Lotta help, eh?

    I don't think you're gonna get much cheaper or easier than 802.11b stuff. You can get USB cards for less than $100 each, 300' is pushing their range but definately possible out of the box. With custom antennas, people get miles outta the things. Bonus advantage, you get the network stack and all the software that works with that.

    If you feel like hacking hardware you might be able to come up with other solutions. Do you have line of sight? Then how about modulating a laser diode? Low bandwidth requirements? How about an old modem and a cordless phone?

    Chris Cothrun
    Curator of Chaos

  • There is a guy on eBay selling 100's of old (but unused so new) ISAPCMCIA adapters for $24 plus $8 shipping (flat shipping so $8 for 1 or more). Or buy the same adapter used from pcliquidators for $19.95 plus reasonable shipping.

    http://www.pcliquidator.com/pcmciadrivebay.htm [pcliquidator.com]
    or
    http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem& item=1252635232 [ebay.com]

    forums.anandtech.com thread on these cards [anandtech.com]

  • Here's a link to a project for using some laser-pointers to do wireless RS-232.

    Not sure about the bandwidth, but it'll cost you about $30 total, plus some work.
    http://www.geocities.com/SiliconValley/Lakes/715 6/ laser.htm

  • Yes, but no... (Score:4)

    by Bryan Andersen ( 16514 ) on Sunday July 22, 2001 @09:25PM (#68027) Homepage
    Yes you can get it setup for cheep, but only if your willing to do some hardware hacking as well as possibly some software hacking. My sugestion is go with the wireless lan. For a two PC setup I'm told you don't need the access point. That brings the price down to a reasonable level.

    Digikey [digikey.com] sells the Linx RF modules which cost $200-$250 for the evaluation kits with all the parts you should need. That's about as cheep as you will get. Note you will need some more hardware linke cases and power supplies. The EV kits just provide 9 volt batteries. Works for testing but not for long term use. After you get the physical link working, now you need to get the software working. That means more effort. Oh, as an after thought. If you are doing this for yourself (not a company) you need to get yourself a HAM license to muck about with RF devices. Otherwise if it's for work, go get only FCC approved devices. Dealing with the FCC regs will quickly cost more than the fancyest gear on the market.

  • I've worked in the embedded field for quite a while and have used BASIC stamps from Parallax [parallaxinc.com]. Some of the optional extras available in their catalog are RF modules. Look at the catalog [parallaxinc.com] and see if anything fits your project. Bi-directional? Get two transcievers. They're $120 each, and support 9600,N,8,1 serial communication. See the manual [parallaxinc.com] for specific details on design and spec.

  • It does not quite reach 300 feet, but it might work and its only $50. The site is http://www.pcliquidator.com/wirelesslankit.htm , I have bought other things from them before and been happy.

    BTW: no I do not work for them, nor am I related in any way that I know of. :)

  • The shady spot under the tree in the backyard.

    A flat blade shovel (to lift up the grass chunks carefully) and a bit of work to lay a PVC conduit would work fine for this.

    My friend's apartment, one floor down and on the other side of the hallway.

    Tougher, but doable given enough ingenuity (pop the cable out a window, perhaps?) - possible use unused phone lines, and rewire the junction box (just don't get caught).

    The garage

    Surely you can run a wire to the garage through the attic, right?

    The coffee shop I live upstairs from

    Tougher, but if you are a regular customer, and they aren't a Starbucks (what I mean is if they are a mom-n-pop joint), maybe you can get them to allow you to run the cable. Or perhaps set up an arrangement, get a fractional T1 and supply internet access to the coffee shop? This one would take some work...

    I am not saying that a wire is right for all applications - but for most apps, it easily and inexpensively does the trick, provided you are willing to go to the effort and sweat to install the thing.

    Worldcom [worldcom.com] - Generation Duh!
  • Well, if the shady spot is moving, put the connect somewhere halfway in between.

    BTW - we are talking serial comms here, not ethernet. According to this [csgnetwork.com] FAQ:

    The RS-232 specification defines the the maximum length of serial cable to be 75 feet at 9,600 bps. This is a pretty conservative figure and has been stretched as far as several thousand feet, especially at this baud rate.

    Even if we were talking 10BaseT or 100BaseT here, you still have 100 meters as spec, and I am certain that is conservative as well - but that is over 300 feet!

    As far as the garage is concerned, it should be possible to reach it in some manner - but given the situation, I would forego the access - it just doesn't sound worth it. Still, it could be done - it wouldn't be easy, and you might need to get help from neighbors (to string the cable on the outside of the building) - but it could be done (the hard part would be getting the building owner or landlord, depending on the situation, to allow you to do it, or to sneak it past them).

    Your point about the ethernet outlet is taken - but that is why every self respecting geek brings along a battery powered hub before jacking in.

    Worldcom [worldcom.com] - Generation Duh!

  • Why? (Score:4)

    by cr0sh ( 43134 ) on Monday July 23, 2001 @09:52AM (#68032) Homepage
    What is in between 300 feet that you can't string a simple cable?

    If you absolutely have to have wireless, look into radio modems (also known as packet radio [baycom.org]). Most of these are relatively inexpensive, small, and easy to use. Most require some kind of backend transmitter/receiver - a cheap hacked CB would work.

    Also, look up homebrew lasercomm systems - some of these use actual lasers (here [geocities.com] is one such project) - I have seen one (Ronja [mff.cuni.cz]) that uses high brightness LEDs.

    There are many solutions to this problem - but the cheapest (not to mention easiest, and quickest) one is a cable.

    Worldcom [worldcom.com] - Generation Duh!
  • Yeah, they used to make these beasties, basically a 115 serial over short range radio.. Logitech made them, among others.. Why? PCAnywhere and Interlink used to be popular for ad hoc networks..

    Troll ebay..
  • Since you say it worked for you can you comment on the review on the page you reference that isn't glowing, however does say that with some computer knowledge (above the average user, however not scary to me) you can get things rolling?

    Do you have any experience using this setup with non-MS OS environments? I have a laptop I'd like to use next to my whiteboard to write simple files and have them write back to NFS shares so this thing's speed is fine, and the price looks fine, however the laptop is old (does have PCMCIA) and I just boot to a console login and fire up vim so I don't want an MS GUI hogging up the place.

    What is your use experience? How does it compare to my intentions?
  • > Isn't this exactly what bluetooth is for? Bluetooth is meant for very short range wireless communication. Up to several meters at most.
  • The LC series (TXM transitter for about $8, and RXM receiver for about $13), combined with a MAX232 chip, a couple capacitors and an antenna can make a 9600 link for about $25/end and a little bit of time. Just get a MAX on each end, a matched radio pair for one way, a matched pair on a different frequency for the other way (you could do half duplex, but...), and you're set. They advertise around 300ft for the LCs, and they draw 5v if I remember right.

    They also have a couple other series with different characteristics (some with quite a bit higher speeds).
  • Bluetooth is dead. It's too complicated, too obtuse, hopelessly slow and ridiculously expensive...
  • Isn't this exactly what bluetooth is for?

    Aren't there supposed to be products out already?

    If bluetooth really lives up to its claim of USD5-10 buck devices, then go for it. But if it's not cheaper than WiFi forget it- don't pay more for less.

    Cheerio,
    Link.
  • if you don't need a lot of bandwidth...just talk with modems over regualar phone lines...
  • Forgot to mention, you will need to get the output voltage on the recievers to the same level as the serial port. That I do not know. I have three pairs of these things that I have been wating to use, but I haven't had the time or idea for a use besides a do it yourself remote controll system. This requiors more stuff for a signal encoder and decorer. The serial ports would handel that on their own though, as there is only a ground, a transmit and a recieve on them if I remember correctly.
  • www.pricegrabber.com often has better prices, if you know the part/model number.

  • Build it yourself (Score:3)

    by squeegee-me ( 169687 ) on Monday July 23, 2001 @07:54AM (#68042) Homepage
    If you have the knowhow, Tech-America/Radio Shack have 433 Mhz transmitters and recievers in their catalog. They have about a 200m range, and if I remember from the pinout diagrams, they don't need much more than power and a signal feed. They cost about $20 for a pair, and the two will fit in a film canister. The one is as small as two dimes stacked. I think you could easly grab a pair of DB9 connectors, and a pair of each of these, and throw in a battery or two. End result serial port plugs that work with eachother. Only drawbacks might include power draw on the batteries, getting the two tranceivers and two recievers to run on diffrent frequencies, and finding the limit of data speed through them. You might be able to adjust the RF with a standard police scanner and a test tone, and then adjust the reciever using a speaker and a small amp circut. The units can be found here, [radioshack.com] and there is no FCC licence requiored. Also they support both analog signals and digital signals, but they us AM instead of FM for the signal type.

  • WiFi cards are cheap and easy (Score:3)

    by Helix150 ( 177049 ) on Monday July 23, 2001 @03:33AM (#68043)
    Dude all you need is some WiFi (802.11B) gear. Get one card for each computer and run in ad-hoc (no base station) mode.

    First get two WiFi PC cards [buy.com]. Yes I know you dont have laptops. Add two PCI-PC card adapters [buy.com] and you're set. Total cost $140 per computer, and you get 11MBPS. Also includes encryption if you feel paranoid.

    This is industry standard gear, so if you ever decide to upgrade to a 'full' wireless lan you can get a base station and add as many computers as you want.
  • I didnt mention this, but the older (28.6kbs) Richochet modems can be found on Ebay every so often for little more than a song. If your just doing a serial terminal to some hidden box, this may be enough.
    The newer Ricochets are 128kbs, but run about $50 each on ebay.

    Kalrand
    -The Voice of Reason

  • Old Ricochet Modems! (Score:4)

    by Kalrand ( 177637 ) on Monday July 23, 2001 @06:28AM (#68045)
    The simplest wireless-serial connection that you are going to get is if you use a pair of old richochet modems in their direct transfer mode.

    This might require you to hack a bit of software, but it is a true wireless serial link.

    Here's a link on how the whole thing works.

    Ricochet Modem FAQ [enlightenment-engine.com]

    Kalrand
    -The Voice of Reason

  • whoops didnt see the 300ft distance.It only works up to a meter
  • Have you thought about IR. A company called extended systems makes serial and usb ir dongles that depending on your os may allow data transfer up to 4 mbit if you can use usb, 115K if you use serial.You should be able to get 2 of them for about $50-100 total for both.Thats of course if the computers are close enough together. I know there is support for most of the M$ operating systems, but Im not sure about the level of support for infrared in linux
  • If you do end up going Wireless LAN like some on here have mentioned, go get it at the cheapest price. Goto Pricewatch.

    www.pricewatch.com

  • What is in between 300 feet that you can't string a simple cable?
    A simple answer would be something like:
    The shady spot under the tree in the backyard.

    Others include:
    My friend's apartment, one floor down and on the other side of the hallway.
    The garage.
    The coffee shop I live upstairs from.
    etc.


  • Down here in europe, Siemens used to sell a DECT (http://www.dect-mmc.org/) modem. You did get two external units witch you could connect to your PCs through standard RS-232 serial interfaces. Take a look at http://www.my-siemens.com/MySiemens/CDA/Standard/F rameset/0,1649,3_GIGASETM101DATA_0_1_61_0,FF.html .
  • I wondered about this before. 2.4Ghz cordless phones run $50 a piece in the clearance rack, a 900mhz one can be found for $20 or maybe less at big lots.

    Then you just grab 2 modems, you should be able to get those free or for a few dollars each.

    I'v wanted to do this for the longest time.

  • that is funny
  • Er, no - bluetooth is a "personal area network" technology, not more than ~10 metres I'm afraid.

  • Timeline Inc., Torrance, CA, Tel: 310-784-5488, FAX: 310-784-7590 is now selling "surplus" PROXIM RF Modems for $99.00 each. "Installation schematics and application details" are also available from Timeline.

    linux robotic webcam - no plugs - no java [vidcard.com]

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