Forgot your password?
typodupeerror
Wireless Networking Science

Ask Slashdot: Wireless Proximity Detection? 101

Posted by timothy
from the olpc-machines-can-just-ping dept.
New submitter Cinnamon Whirl writes "As a chemist, I work in a both lab and office enviroments, and need access to data in both, without causing undue clutter in either. My company has recently purchased two Win7 tablets for trial usage with electronic lab notebooks, propietry software, SAP, email etc. These are also useful for sharing in meetings, etc. As part of this project, I have been wondering whether we can use these tablets to detect other devices by proximity. Examples could include finding the nearest printer or monitor or, perhaps trickier, could two roaming devices find each other? Although lab technology is rarely cutting edge, I can see a day when all our sensors and probes will broadcast data (wireless thermocouples are already available), and positioning information will become much more important. What technologies exist to do this? How accurate can the detection be?"
This discussion has been archived. No new comments can be posted.

Ask Slashdot: Wireless Proximity Detection?

Comments Filter:
  • by maccodemonkey (1438585) on Sunday January 29, 2012 @08:00PM (#38860433)

    See the Wikipedia entry on Bluetooth. Listed in the use cases for 4.0 (otherwise known as Bluetooth low energy):

    "Mobile phones, gaming, PCs, watches, sports and fitness, healthcare, security & proximity, automotive, home electronics, automation, Industrial, etc."

    • by Osgeld (1900440)

      wait what? beaming proximity data over bluetooth does not mean that bluetooth can naturally act as a proximity detector

      • Bluetooth Proximity (Score:4, Informative)

        by jginspace (678908) <.jginspace. .at. .yahoo.com.> on Sunday January 29, 2012 @09:54PM (#38861011) Homepage Journal

        wait what? beaming proximity data over bluetooth does not mean that bluetooth can naturally act as a proximity detector

        These guys have been disagreeing with you for several years:
        BtProx - Bluetooth Proximity Lock Utility [sourceforge.net]
        Bluemon [matthew.ath.cx]

        • Re: (Score:3, Informative)

          by erikscott (1360245)
          Going back a ways, the first time I heard of using Bluetooth to tell what room you were in was from this paper:

          http://dspace.mit.edu/bitstream/handle/1721.1/7431/CS021.pdf [mit.edu]

          Bonus points for running Bluetooth USB adapters without actually having a computer connected (at least after startup). I experimented some with this sort of scheme and my one warning is this: it takes 10.24 seconds to check all possible hopping patterns for all possible Bluetooth devices, so if it needs to respond quickly, you're h

          • by camperslo (704715)

            I hope this all isn't going to be used for any sort of process control. If a malicious signal can spoof a temperature or pressure sensor, things could go horribly wrong. It is the same issue that one must be aware of when designing with wireless interfaces to PLCs.

      • There used to be an old yarn about being an engineer at Apple. If you were on the elevator and happened to be lucky/unlucky enough that Steve Jobs stepped onto the elevator with you, by the time the elevator reached your floor you would either have been promoted or fired. Whether true or not, it was very well known that Steve Jobs was very tough and demanding on engineers. He would routinely prowl through the engineering departments to surprise people with spot checks.

        For creative people, this kind of intru

        • by Osgeld (1900440)

          well thats all great and fine and good but the use of bluetooth in this MESH NETWORK is purely convenience it could have been any radio system, and I still stand behind my original statement

          buzzword or not having a transmitter on you does not make it an instant proximity detector, you could make it into one like above using a mesh network, or you could triagulate it, but it doesnt fucking matter if its bluetooth, wifi, xbee or a fucking AM radio source playing Hank Williams

    • by dissy (172727) on Sunday January 29, 2012 @10:56PM (#38861349)

      I used a similar Bluetooth setup in my old house with my phone system.

      My VoIP setup had multiple outside lines (up to 12, fees were for usage), and numerous internal extensions.
      I tossed some scripts together for my computers around the house to watch for the bluetooth signal from my cell phone, and routed the call depending on that data.

      If my cell phone was in my kitchen, calls to my main # got redirected to the extension in the kitchen.
      If my cell was in the bedroom, calls got routed to that extension instead.

      If my cell was no where to be seen in the house, calls to my main # were forwarded to my cell phone number, under the assumption I was not in the house.

      This saved me from using my cell phone battery while inside, but when I was out calls routed to me none the less with no configuration changes, or having to remember to flip some switch when leaving and returning.

      It was pretty neat to have the phone in the family room ring once (as I was already walking upstairs) and have the ring "follow" me from there to the kitchen extension and finally to my bedroom before answering.

      Behind the scenes it was a mess of asterisk configs/scripts, shell scripts, and some wrapped TCL executable for the windows machines.

      But it was fairly straight forward work, not too difficult. This should be very doable as long as one has a little bit of programming (or really even just scripting) experience to glue all the bits and pieces together.

      • by Anonymous Coward

        Would you mind throwing those up on Github or something so Google can index it for those of use who are interested in doing that ourselves?

        Thanks!

        • by Xacid (560407)

          Seconded! This is one of the coolest hacks I've heard of on /. for a good while.

    • by Shoten (260439)

      I think you're missing the point of what he is asking. Redesigning all the devices in his world is not an option; he needs to do proximity detection across multiple wireless protocols. You know, it's this approach that gives geeks a bad name. "Oh, that's easy, just make EVERYTHING use [new unreleased technology that isn't even available yet]!" Yeah...in the real world, you have to work within the less convenient reality that you have to buy off-the-shelf, and that you don't get to design the entire uni

      • by gl4ss (559668)

        "What technologies exist to do this? How accurate can the detection be?"

        you can use older bt tech too. the range is the kincher, really. or just use nfc, but then you might be just be able to detect that the device is on top of the other device. the whole question is stupid if they have a lab etc, they should have info already about available tech - though the question is posed more like "is there sentient magic that we could use?".

        (and if you need some wild ideas, how about using ultra or infra sonic?)

    • by Anonymous Coward

      Bluetooth's security is terrible, even in version 4.0. If you use it for proximity detection, it would be easy to mess up the transmission (e.g. injecting new devices, removing existing devices, etc). If you also use it to transmit sensor data, all values can be altered.

      I realize that this probably doesn't matter in the particular case described in the question, but I imagine that a lot of people might try to find solutions to their related problems in these comments.

  • BlueTooth or RFID (Score:5, Informative)

    by cluge (114877) on Sunday January 29, 2012 @08:12PM (#38860475) Homepage
    Bluetooth is a good option, also look at RFID. There are RFID kits that are windows compatible. Check it out and hopefully this will help get you started as to some of the possibilities. http://www.trossenrobotics.com/p/RFID-experimenters-kit.aspx?feed=Froogle [trossenrobotics.com] -cluge
  • I always just take a look at my router page to see what devices are connected. And most of the time most devices will already have software for searching for other capable networks. Maybe you could just have the routers log emailed to you regularly.
  • by Dan East (318230) on Sunday January 29, 2012 @08:19PM (#38860505) Homepage Journal

    In what way is your tablet making wireless use of a monitor? Are you talking about a computer workstation, or just a standalone monitor?

    I can't see ad-hoc networking being very useful for instrumentation. I would think you'd want sure fire, dedicated, reliable data capture and not random hodge-podge as far as that goes. For example, an instrument in the lab finds Tablet A and dumps its cached data to that tablet. The user of Tablet A promptly leaves the building and the data is now stuck on his device which is out of range. Worse, Tablet A is then dropped in a stream of molten lava in the field, and the data from that instrument is lost for good.

    I think you need to better define exactly what you're even wanting proximity detection for in the first place - specifically, when two devices find one another, what is the point? Printers are one of the few things that makes some sense for proximity, but even in that case, how many printers are you talking about that it is too tedious to pick the desired printer from a list? What if you don't want to print to the closest printer, but the one nearest your office? Or the printer back at the office while you're out in the field? I would think printers in a lab would be part of the infrastructure, and not an ad-hoc wifi network. Further, you're usually better off with your tablet connecting to a WAP and accessing the LAN, instead of trying to wirelessly connect to individual devices like printers directly. In that case the whole concept of proximity is out the window unless your talking about PAN (bluetooth) type peripherals like keyboards and mice.

    WAPs are usually strategically located for maximum wireless coverage, whereas things like printers and instruments are situated in entirely different locations where they are easy to reach (and thus suboptimal from a wireless perspective). Proximity could actually be a bad thing - it is really just a restriction. Wouldn't you want to be able to access a specific instrument whether or not you were in direct wireless range of that device?

    • by mjwalshe (1680392)
      Yes from experience working on large scale mixing experiments at BHR group we used to use a brand new set of batteries to power the sensors (mounted on the rotating elements) for each run - as the materials for a run cost £20,000 (at the time about 1/2 the cost of a house
    • by hawguy (1600213)

      WAPs are usually strategically located for maximum wireless coverage, whereas things like printers and instruments are situated in entirely different locations where they are easy to reach (and thus suboptimal from a wireless perspective). Proximity could actually be a bad thing - it is really just a restriction. Wouldn't you want to be able to access a specific instrument whether or not you were in direct wireless range of that device?

      Wouldn't the answer be to have the printers and instruments connect to the building Wifi and store their data on a central server than to have them connect to the nearest laptop?

    • I can't see ad-hoc networking being very useful for instrumentation.

      Honeywell OneWireless
      "The OneWireless Network is an industrial wireless network that forms a fully redundant and self-healing mesh network to support Wi-Fi devices and industrial I/O devices simultaneously."
      http://hpsweb.honeywell.com/Cultures/en-US/Products/wireless/default.htm [honeywell.com]

    • For example see the failed Sun Jini [amazon.com] circa 1999-2000.
    • by dissy (172727)

      For your data example, just replace 'mv' with 'cp' and all your problems disappear.

      For the printers, use proximity to set the default selection, still letting you pick a printer from the list if you wish to override.

      As for WAP restrictions, that's a huge stretch. Of course no one would want to do that, you choose an AP by user preference first, and if anything signal strength second.

      Proximity detection is used as the trigger to initialize connections and get things ready for YOU to use them so you don't ne

    • specifically, when two devices find one another, what is the point?

      This has to be the ultimate Slashdot question. On other fora, I think devices just follow their...um...BIOS.

  • by artor3 (1344997) on Sunday January 29, 2012 @08:32PM (#38860577)

    There are two ways to use RF signaling to gauge distances.

    The easy (but not at all accurate) way is to use signal power, relating higher received power to closer proximity. This method is very inaccurate, as the shortest path might not be (in fact, probably won't be) the path with the least attenuation. You can do this sort of thing in a wide open space, but in an office environment it's likely to be all but useless. It gets even less accurate when you introduce mobile devices, since the antenna's orientation is likely to be changing depending on how you hold it, which can vary received power by several decibels.

    The better way is with timing, similar to how GPS works. However, you still have the "shortest path != least attenuated path" problem. For example, consider a signal that follows two paths to reach the receiver. One travels 100' and experiences 70 dB of attenuation, the other bounces around a wall instead of going through it, and ends up traveling 150' while only experiencing 60 dB of attenuation. After ~50 ns, the signal from the first path (which accurately represents the distance) will be swamped out by the signal from the second path. In order to get the info you need, you have two options: Either use a very high throughput signal (>1 Gbps) or have a special receiver architecture that recognizes those first symbols were an earlier path of the received signal and notes the time at which they arrived.

    • The better way is with timing, similar to how GPS works. However, you still have the "shortest path != least attenuated path" problem. For example, consider a signal that follows two paths to reach the receiver. One travels 100' and experiences 70 dB of attenuation, the other bounces around a wall instead of going through it, and ends up traveling 150' while only experiencing 60 dB of attenuation. After ~50 ns, the signal from the first path (which accurately represents the distance) will be swamped out by the signal from the second path. In order to get the info you need, you have two options: Either use a very high throughput signal (>1 Gbps) or have a special receiver architecture that recognizes those first symbols were an earlier path of the received signal and notes the time at which they arrived.

      Once you have the device identified, you can use the strongest signal for subsequent communication.

  • As a few has already mentioned, Bluetooth is an appropriate technical solution to the problem described. However, the environment you propose for this to be implemented suggests compliance with cGLP (current Good Laboratory Practices). In that case, whatever technical solution you implement will need to undergo qualification/validation to various degrees. This is somewhat more involved than finding (or slapping together some code of your own to create) an app to run/manage your equipment. If a potential
  • http://en.wikipedia.org/wiki/ZigBee [wikipedia.org]

    Lower power and cost. Suitable for sensors, but unlikely to see it integrated into tablets or netbooks though.

    • by Anonymous Coward

      Bluetooth 4 is in the iPhone 4S, the latest macbook air, and the Motorola Android Razr. It seems likely to come to tablets soon.

    • by the_B0fh (208483)

      and next to no security. wheee!

      • by Anonymous Coward

        I'd much rather the link layer provided no security than broken security [usenix.org] like Bluetooth. If the link layer provides no security, higher layers will provide their own. If the link layer provides an illusion of security, higher layers might make the mistake of trusting it.

      • If you're close enough to use bluetooth, you're generally close enough to have physical access, especially in this context.
  • by ihtpsswrds (647476) on Sunday January 29, 2012 @08:56PM (#38860693)
    While seeing the closest is a tempting thought experiment, it may not be a practical solution for your actual workday (nearest printer may be low on toner, you may want these results in someone else's hands, etc). I'd still recommend what we do in our hospital by setting the shared device name with a zone number to indicate where it is. Your idea would be a great application for an RFID system with a map feature. Anyone have an idea with an existing app?
    • by jittles (1613415)
      Sure there are security systems that are already designed to use maps. I am sure the software could be adapted to do this, but it probably wouldn't be cheap.
    • by houghi (78078)

      If printing is the only requirement, then there might be other options available. The printjob gives you a code that you enter at any printer.
      Disadvantage is that you must wait for a print job. Not an issue if it is very few pages. Hell if it is several hundred.
      Giving printers a location name might be better. Disadvantage there is that sometimes printers are moved and people cant find the printer they used as a default and the printer does not get a new name for its new location.

      Because of this we had peopl

  • Sometimes I think all computers should have autocorrect...
  • ...Is the only way to do it. Not 100% accurate but it can be done.
  • I'm not entirely sure how my employer does it, but depending on what lan port or wireless ap a computer/laptop is connected to will set up the correct printers for the office floor.

  • by tomhath (637240)
    It sounds like you want a Local Positioning System [isi.hevs.ch]. Not available as an out-of-the-box solution yet (AFAIK), but will probably become popular within the next few years.
  • There is a really lame commercial with some mock do-gooders who recover an elderly ladies purse, then charge her for their services. Not surprisingly, they are using Windows mobile device, and print her invoice on the nearest printer.

    If your lame-ass tablets don't do what the commercial says, toss them and get an iPad or two. Rendezvous/Bonjour/mDNS, as they say, "just works", without embarrassingly sophomoric ad campaigns, or blatant astro-turfing like your query.

    If tossing them isn't an option, root t

  • It sounds like what he wants is wireless, bluetooth, or RFID readable sensors. If the lab employee is near the sensor it can display the data from the sensor on the tablet. Still doesn't address reliable recording of that data, although they are likely manually recording this data on notebooks already.

  • Just have a look at http://sourceforge.net/projects/blueproximity/ [sourceforge.net] (mac), http://www.daveamenta.com/products/btproximity/ [daveamenta.com] (windows), http://blueproximity.sourceforge.net/ [sourceforge.net] (linux). This will detect you when you walk by with your bluetooth device. You can trigger actions as desired when in range - http://hints.macworld.com/article.php?story=20091221173111783 [macworld.com] . There is even a commercial alternative - http://themha.com/airlock/ [themha.com] .
  • This sounds like a solution looking for a problem.

    If you have a sensor then the data is important, and not just when you are looking at it with your eyeballs. Most likely the data will be logged in a data logger, historian or LIMS database. Whether you use wired or wireless sensors, you've not just going to throw them into the feild randomly - each one will be individually configured in the database and given a meaningful name/identifier. Transmitting proximity information is thus irrelevant for data sto

  • by Rich0 (548339) on Sunday January 29, 2012 @11:21PM (#38861451) Homepage

    ...these sorts of technologies in the labs: wireless is often overrated unless you really need it.

    It makes sense for your tablet. It doesn't make so much sense for that balance that needs to be leveled and calibrated anytime you shift it an inch anyway. Just use reliable wired connections for these sorts of things.

    That doesn't mean hooking up a wire to your tablet. If the balance is wired to a network, and your tablet is wirelessly connected to a network, then they are already connected.

    And, for any kind of serious data collection you don't want the instrument directly talking to a tablet anyway. The instrument should be talking to a server somewhere that is always running and capturing data, and then your tablet can connect to that server when it needs data. Oh, and if you're at home you can connect to it as well that way.

    I can't tell you how many installations I've seen where some scientist got some money to have some consultants set up some kind of fancy data acquisition system in their lab. Inevitably it stores all its data on some PC that has no backups of any kind sitting in the lab. Of course, chances are the reason that they did it that way was that they're used to people in corporate IT just impeding progress, so they work around them. The right solution of course is cooperation - let the consultants handle their software and instruments, and have corporate IT provide the secured servers that they store data on. If your IT department is really sharp maybe they can actually help you work through what kinds of data is being collected where and help get it properly connected so that you aren't drowning in excel spreadsheets on flash drives.

    However, all of this is a pipe dream. Small companies often don't have the resources to do something like this right, and big companies usually have managers who are too interested in their own empires to exhibit the kind of cooperation that I describe here. So, everybody micro-optimizes their piece of the puzzle and crosses their finger that there isn't a fire.

    • by dkf (304284)

      Inevitably it stores all its data on some PC that has no backups of any kind sitting in the lab.

      If you're unlucky, they've used some kind of odd hardware connector that requires a bizarre OCX running on Win98 in order to work at all (and no, it never worked on anything more recent). If you're building a fancy instrument, please make its on-the-wire protocol be either standardized or simple enough that its trivial to reverse engineer. Like that, the kit can be kept working throughout its life with only minimal fuss rather than needing another million or two to be spent on a replacement just because of

  • t-shirt for that. Why reinvent the app? http://www.thinkgeek.com/tshirts-apparel/interactive/991e/?cpg=clrss [thinkgeek.com]
  • You could just install a WiFi base station in the middle of every room on very low power (using OpenWRT or another hackable firmware) and depending on your location have a web server or application that shows you only the instruments in that location (given they're connecting through the network as well).

    Another trick is simply to use GPS. iDevices have GPS in them, most Androids do as well. I don't know what systems exactly you have but most tablets have a GPS optional or put one in a PCMCIA/ExpressCard sl

    • I don't know about you, but my most sensitive GPS (of several) gets in in-building resolution of about 12 metres.
      • by guruevi (827432)

        I can get it down to 1-5 meters within a few seconds in my building (external bluetooth GPS module). There are such things as GPS repeaters as well. Depending on the lab, even 12 meter resolutions might be 'good enough'. I don't know if there are any open source modules to accurately triangulate based on GPS data + the location of WiFi base stations but I know there are commercial custom solutions for it.

        Accurately tracking the location of a in a building is often done in warehouses, I've seen it done and

  • Different vendors have different levels of support of "location services." I know Cisco at least sells a location add-on to its enterprise lightweight AP management system.

    However, from the limited amount I read about it it didn't strike me as being oriented towards allowing users to see their own location, or scripting based on location. Mostly it was aimed at access control and letting security-oriented personell (and PHBs monitoring bathroom breaks) play big brother. So there would be quite a bit of l

  • by crutchy (1949900)
    futurlec or sparkfun... all sorts of cool geek gadgets there, even if you're completely incompetent with a soldering iron, like me

    if you can't see the circuit boards, its just not cool
  • I'm interested in this myself. I see that most people respond to the example given, and not the question. Let's try to suggest some solutions without second guessing the application of which we have a limited view. My interest flows from the fact that Android running on my phone does not support wireless hotspot roaming. I have 3 hotspots in my home, but none of them on their own covers the whole house. So during the day I will have my phone on the wireless, but then at night I will lose connectivity w
  • There's now an iPhone / iPad app for finding your car _even if you didn't remember to start the app when leaving your car_. It uses Bluetooth 4.0 and a tiny transmitter in the car. So the iPhone or iPad will detect when it leaves the proximity of the transmitter and record the location. (It could of course detect when you get near to the car as well, but it is pointless for that app).
    • by flipper9 (109877) *

      But the catch is that you left the Bluetooth option enabled, now your iPhone battery is dead, and now you have no idea where your car is located!

      • But the catch is that you left the Bluetooth option enabled, now your iPhone battery is dead, and now you have no idea where your car is located!

        Idiot.

        Oh, Slashdot thinks that I should think longer about this response. Yes, you are an idiot.

  • Paradoxically, high power does not automatically give long distance since it is usually coupled with modulation for high data rates. For device discovery low power with low bandwidth modulation techniques can give greater range. When you want to send data, switch in a LNA and change the modulation for faster rates.

    Many 802.15.4 systems on a chip can do these things at $5 a pop; e.g. 250K to 2M bits per second, switchable 20dB amplifier, switchable antennas. It is just a matter of writing the software. Proba

  • Check out this old google tech talk:
    http://www.youtube.com/watch?v=6PiMimSrP7A [youtube.com]

  • You should read Apple's spec for Bonjour [wikipedia.org], their implementation of Zero Configuration Networking [wikipedia.org].

    I'm curious how this really made it to "Ask Slashdot" when a quick Google Search shows that this kind of tech has been around for some time (though not always setup or implemented well).

New systems generate new problems.

Working...