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Ask Slashdot: Wireless Proximity Detection?
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?"
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."
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 -cluge
"Science is about ego as much as it is about discovery and truth " - I said it, so sue me.
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.
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?
Better known as 318230.
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.
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?
Just have a look at http://sourceforge.net/projects/blueproximity/ (mac), http://www.daveamenta.com/products/btproximity/ (windows), http://blueproximity.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 . There is even a commercial alternative - http://themha.com/airlock/ .
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
Bluemon
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.
...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.
t-shirt for that. Why reinvent the app? http://www.thinkgeek.com/tshirts-apparel/interactive/991e/?cpg=clrss
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 universe as it would need to be in order to make solving one specific problem easier.
For your security, this post has been encrypted with ROT-13, twice.
celibacy means no whacking it either.
in fact, it includes impure thoughts by most definitions.
I think you mean
"he's a slashdotter, lack of reproductive opportunities is implied"
every day http://en.wikipedia.org/wiki/Special:Random
Seconded! This is one of the coolest hacks I've heard of on /. for a good while.
It is awkward for lab workers to have their mice hijacked, and even more so to lose control of their monkeys.
Always mount a spare monkey.
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 intrusion can be very disruptive -- even the possibility can keep someone from entering "flow state", the scientific term for a mental state creative people enter when they are at their most creative and productive. This in turn, creates a great deal of stress on an individual.
So, a few years ago, not long after Apple added Bluetooth to their computers, another story began to circulate. Jobs started noticing that his surprise spot checks didn't seem to be as much as a surprise as he thought. Engineers would be conveniently on a coffee break, stepping out to go to the bathroom, etc. For some odd reason or another, they just wouldn't be at their desks when he thought they would be. It wasn't just engineering. The effect began to spread to other departments in the company. Jobs began to suspect something after a while, but couldn't quite put his finger on it.
Eventually, the "something" became so widespread, that it was due that someone would slip up, and Jobs discovered what was going on. One of the engineers wrote a program that would listen for the bluetooth transponder in a cellphone and query its serial number. Then, by propagating the program onto computers throughout the company, the system would track Jobs by the serial number of his cellphone via bluetooth. Every time Jobs walked past a computer with the software on it, the computer would send out a signal showing Jobs' position within the company, and that was displayed on a window on any computer listening for the signal. This way, engineers knew when Jobs was on the prowl, where he was, where he was going, and they would know when to clear out to avoid getting blistered by the boss!
The legend ends with Jobs ordering that the software be removed and the engineer who came up with it was given a raise for creative thinking outside the box.
Are there any Apple engineers out there that can prove or disprove the validity of this tale? I did a quick search on Google, but came up bupkis.
Whew! This water sure is cold!