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Hardware

Alternative Frequency Wireless Ethernet Devices? 46

Posted by Cliff from the mutant-devices dept.
rtgree01 asks: "Do Slashdot readers know of any wireless ethernet devices that are not 900 MHz, 2.4GHz, or 5GHz. This is for a project that will be in an extremely harsh EMI area (thousands of V/m at those frequencies). Also, to make things even more impossible, line of sight is not available, even though the range for this system should be 30 feet max. Some of you might suggest to stick with a standard wired solution, but that is not optimal at all. Any suggestions would be greatly appreciated."
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Alternative Frequency Wireless Ethernet Devices? More

Alternative Frequency Wireless Ethernet Devices?

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  • Mirrors (Score:4, Informative)

    by mfos.org ( 471768 ) on Thursday December 19, 2002 @11:16PM (#4927633)
    I don't know the exact setup you have, but IR with mirrors might work

    • Modulated light (Score:3, Informative)

      by Futurepower(R) ( 558542 )
      He's right. Modulated light avoids electromagnetic noise.

      • Re:Modulated light (Score:2, Interesting)

        by Anonymous Coward
        Not if the e.m. noise is at the frequency of the light. :-)

        • but if the interference were in the frequency of IR light, it would be illegal as the FCC rules out non-IR signalling in this band of light. Unless TV Remote Controlls are being used extensively. Anyway, light is a physical thing, it is not radiation and is not succeptible to "blockout" level noise from any legal EM radiation.
  • --was reading here last month or so about using lasers for data transfer. Maybe find that thread/company/method, then use strategically placed and aimed mirrors to "force" a line of sight?

  • How much bandwith? (Score:3, Informative)

    by thefatz ( 97467 ) on Thursday December 19, 2002 @11:52PM (#4927681) Homepage
    How much data do you plan on sending? Data over ham might work. You might be able to find some 19.2kbps wireless modems that work together. Any Ideas?
    • not if this environment is commercial, that would be illegal.
    • Um, you know it's illegal to transmit encrypted data over amateur radio, right? Kind of shoots any security out of the water, which is probably a bad idea for his network..

      ~GoRK

      • Re:How much bandwith? (Score:3, Informative)

        by Komodo ( 7029 )
        I don't think it's actually illegal to transmit encrypted data , but you have to keep a copy of the transmitted data (in the clear) for inspection by certain parties, definitely including the FCC.

        What makes it illegal is that it's abusing a part of the spectrum that's reserved and licensed for a particular type of operations (amateur radio). You need to be licensed, and the terms of the license prohibit commercial use - there's very specific rules about that.
        • this is in the Citizen Band, theirfore not requiering FCC license. this band is also available for Commercial use as long as exsisting channel space is respected.

          if you abide by the power output and antenea hight you can use these channels for anything you want, except any encription method used is succeptable to hacks as it is LEGAL to listen and use any information broadcast on CB channels because that information is public domain while it is in transmission. if you want to use this for a network, get some really good encription.
    • Data over ham might work.

      Plug that ethernet card right into a pigs ass and see what happens!!! Seriously tho, isn't this being done using packet radio?

  • 30 feet? (Score:5, Funny)

    by Neck_of_the_Woods ( 305788 ) on Thursday December 19, 2002 @11:59PM (#4927711) Journal


    30 feet that is it? Hell use sneaker net and pay a intern 5.25 and hour to run the data back and forth.

    Get a marketing intern for 10baset, a business intern for 100baseT, and a CS intern for 1000baseT. Keep in mind for the 100/1000 you going to need 2 interns for the full duplex.

    If you want to figure out what is going on with your workers just pick up one of the tri delta girls and set her to permiscous mode......

    • Such a system is capable of high bandwidth, but the latency sucks. Especially during lunch time and afternoon break time.

      Tri-Delta girls aren't particularly good girls with regards to networks. Remember that 2 out of 3 go down (an classic joke refering to their logo). Do you really want a 66% system failure rate with your network?

      • Re:30 feet? (Score:2, Funny)

        by Zerth ( 26112 )
        > Remember that 2 out of 3 go down (an classic joke
        > refering to their logo). Do you really want a 66%
        > system failure rate with your network?

        I dunno about you, but that statistic sounds like a 66% success rate to me:) Your latency is shot already, who cares if most of the packets take another 3 minutes to get there, they will be very happy packets and eager to be retransmitted!
  • Any kind of standard high-speed networking will not function in a high EMI area -- cabled or uncabled.

    I think the military uses a semi peer-to-peer wireless network between armored vehicles and some helicoptors. It is some sort of spread-spectrum technology that violates FCC rules and costs millions of dollars.

    If you cannot run shielded cable or fiber optics, you need to redesign your facility, period.

  • Creative Ideas (Score:4, Insightful)

    by the eric conspiracy ( 20178 ) on Friday December 20, 2002 @12:01AM (#4927725)
    High EMI, mmmm.

    Since line of site and wires seem to be out, maybe more creative ideas are needed. Since you don't say what the data transfer rate needs to be, I'll assume it's not high.

    For low rates perhaps sound pulses would work. This would bring meaning back to the term "ping".

    Another possibility would be paper tape. A pair of writers/readers with the tape running between them would be immune to EMI, and the tapes go around corners nicely.

    Ham radio operators have been sending TCP via radio at all frequencies in the electromagnetic spectrum for many years. While you say that the common frequencies are no good due to EMI, how about elsewhere?

    Another possibility is a hybrid system; wires where they work well, optical where EMI is high might work well.

    • First, I've got to say - I love the paper tape idea - reminds me of the punched metal tape used by the US military for hyper-critical information. If we're talking about kV/M, that's going to overwhelm most frontends... at least, any I could design, and most system internals, too. Paper tape could pass through a thin slot, keeping that EM out of the system, but it's extremely-low bandwidth, and uses up physical supplies. 30 meters, not line-of-sight.... How about infrared? Maybe, if the path isn't particularly high albedo, do some custom hardware work to power-up the transmitter (in this case, there's not much you can do for the receiver)... an op-amp driving a BIG HONKING IR LED is probably all you need.... In fact, do that anyway, unless it works well with stock equipment. I've heard of functional ad hoc networks using IR. If the space seen by the receivers is not brightly-lit, and not super-hot, you can probably get a nice 96kbps network that doesn't fluctuate as people walk between the nodes (enough multipath to fill).
      Incidentally... a nice feature of fiber networking is that it doesn't give a rats ass about electric fields or potentials. Can you just drop or hang fiber? That will make you all but bulletproof, with very large capacity.

  • Other requirements: (Score:4, Funny)

    by Hubert_Shrump ( 256081 ) <{moc.liamg} {ta} {tenarboc}> on Friday December 20, 2002 @12:17AM (#4927778) Journal
    It must be Open Source.

    It must look pretty.

    It can't be composed of matter.

    It can't have been thought of by a carbon-based lifeform.

    It must call me 'Capt. Studjammer' or at least 'Sir Booth Studdington'.

    Pancakes!

    24/7 always-on paradigm outside the box proactive functionality.

  • Posted on Slashdot earlier, there is a program for Linux that will turn any radio attached to a serial port on your computer into an IP-addressable device.

    Your network's operating frequency would only be limited by the hardware in the radio, and of course the speed would be limited by the serial port, which is IIRC about 256kbps.

    Plenty fast for a "logic" connection, such as syncing two systems or for IPC between them, but transferring large quantities of data is going to get long.

  • Why and where (Score:4, Interesting)

    by WindBourne ( 631190 ) on Friday December 20, 2002 @02:46AM (#4928153) Journal
    I am curious what environment that you need this at where you u have large amounts of voltage and signal, yet do not have control of the area? Off hand, this makes no sense unless this is needed to get around something that you are not supposed to be in. The implication is that you have a fence with high voltage and windowless wall to communicate through, like a prison. Otherwise, I suggest if you have permission/autharization, then use fiber (30 ft) or use laser.

  • GENRIP (Score:5, Informative)

    by nesthigh ( 447909 ) on Friday December 20, 2002 @03:16AM (#4928248)
    Depending on the amount of data you need to transmit.. GENRIP [dodinc.com], GENeric Radio IP, based on STRIP [stanford.edu] , may work for you. As discussed here [slashdot.org] before, it basically extends IP over any serialized radio. So, you can choose your own frequency and power.

    next
  • I was going to say mirrors and morse code, but without line of sight, that's out. Otherwise, smoke signals should do the trick. Do you have any specific bandwidth or latency requirements?

  • Eh. I'm not an expert, but isn't 900MHz the base frequency of (older) GSM phones? ' Guess telcos won't be very enthousiastic about the idea of sharing it...
    • GSM 900MHz is in eurpoe and something else too. State side its GSM 1900MHz. 900Mhz is also the base to many cordless phones state side.

      I'm the generic ip over radio seems to be the best idea so far. or maybe the interns.

      • Re:900MHz (Score:2, Informative)

        by Koos Baster ( 625091 )
        Checked that. Europe uses 900, 1800 and 1900Mhz (a triband phone can use all of them).

        Slightly off topic; the 900 Mhz appears to use more energy, so you're probably best off with higher frequencies. This may be a reason some telcos have already decided to ditch the older 900Mhz frequency in favour of the others.

  • If you have high EMI in your environment, copper cable and radio will have much trouble, no matter at which frequency they work. You need to use either sound or light. Sound (ultrasonic) is very rare in networks (at least I do not no any solution for IP over ultrasonic), light leaves two possible solutions. IrDA (at any speed) and some mirrors, like someone else already proposed, or optical fibre. If you need to move your devices, you have to use IrDA, maybe with mirrors at the ceiling or other optical tricks (like lenses). Otherwise, just stick with plain old ethernet over fibre.

  • *strokes cat* la-ser (Score:3, Interesting)

    by awx ( 169546 ) on Friday December 20, 2002 @11:02AM (#4929575)
    Lasers modulated by the output from an ethernet port or serial port with PPP, redirected with mirrors?

  • License (Score:2)

    by GoRK ( 10018 )
    If frequency is your only problem, then you need to figure out what frequencies are clean, then get a license to use a clean frequency and the corresponding equipment to go with it. Alvarion has a lot of stuff available for use at 3-4GHz, and there are other companies that have UHF stuff between 300-800MHz.

    Your other option is to put hook standard equipment up to modulators that will change the frequency. I have worked with devices that double the frequency of 2.4ghz devices to 5.8ghz for use in areas of 2.4 congestion for wireless isp's. There are bound to be other such devices out there.

    ~GoRK

  • Fiber? (Score:3, Informative)

    by wowbagger ( 69688 ) on Friday December 20, 2002 @12:43PM (#4930204) Homepage Journal
    It sounds like this guy needs to communicate to some device that is at a different potential than the rest of the system.

    Have you considered using fiber? High bandwidth, pretty much immune to RF interference, high voltage isolation.

    However, if the target is moving around (some sort of industrial machine, perhaps?) this might not work.

    That's the problem with a lot of Ask Slashdots - the person asking really cannot give a lot of information about his needs, so we cannot weed out suggestions that won't work.

    • Re:Fiber? (Score:3, Informative)

      by wik ( 10258 )
      >That's the problem with a lot of Ask Slashdots - the person asking really cannot give a lot of information about his needs, so we cannot weed out suggestions that won't work.

      Nor will s/he give information about which frequencies *are* good. If a clue isn't given, expect plenty of useless answers. In addition, there is no justification for why a wired connection isn't optimal (and how "optimal" is defined in this situation). It almost seems as if this person doesn't want an answer!
  • Have you looked into contacting companies that make other data equipment for that sort of environment?

    Companies like Allen Bradley, Omron.. etc..

    They deal with high EMF areas all the time in manufacturing plants..

    So even if they DONT have a wireless solution, they have been asked, and prolly know of one.

  • Other people mentioned this but just a little more info. Ham radio would give you more then enough choices of freq. and a good speed choice too(300bps - over 1M/s) BUT, you would need a license(not hard to get, quick 50 or so question test and $6.) Also, you wouldn't be able to use it for anything buisness related. if you just want to experminent then this would be the way to go. I've found 70cm band(around 440MHZ) to be fairly clear in noisy places and if its too noisy, you may just have to lower the speed but it still could work. Equipments spendy too though and for real high speed you might have to build some yourself. Borrow a wide band receiver and see what freqs are clean in your facility.

    -Tom
  • Just thought of this too...have you tried a different antenna? a beam ant would be small at those freqs. and would cut out alot of noise off the back and sides of it. It would also direct more of your signal at the other machine. You only need to get above the noise, not cut it out completely. I believe all these devices are FM so if it can grab on to your signal it should ignore most of the noise.(like when your driving and your between two radio stations, you only get one or the other, not usually both). Just another idea that would be much cheaper. Oh, and good filtering would help too.
    -Tom

  • Maybe... (Score:1, Funny)

    by Anonymous Coward
    You should just stick to drums.

    I heard those worked really worked well in ancient times.
  • Check out GENRIP from http://www.dodinc.com Provides IP connectivity over pretty much any wireless serial line device.
  • sounds like a job for rfc 1149 [rfc-editor.org]

  • It isn't ethernet, but what the heck:
    A little birdseed goes a long way....

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