CMU has a system for doing the triangulation via signal strength with 802.11b.. I think they use it mostly outside but works inside too.. but as you said, walls and such could affect it. If you measured throughout the building though, and took that into acct you could get the accuracy better I would think. Accelerometers are going to drift and your computer will think you are two flights up, three doors down in a few minutes.... unless they cost as much as an HMD and you have the soft to go with it..... -Bryan Hurley On Fri, 30 May 2003, McCarty, Paul wrote: > I would say this is next to impossible. We've looked into various > methods of augmenting GPS and since 802.11b, etc. doesn't have a > directional antenna (nor would I venture to guess how difficult this > would be to build), you have to rely on triangulation and signal > strength, or triangulation and timing of packets (similar to gps). I > know there are some hooks to measure signal strength, but all it takes > is one wall thicker then another and you lose signal strength. Or a > floor say? You'd be better off writing coordinates on the wall! :-) > > Another alternative is they sell GPS repeaters. But I imagine this is > very expensive! > > I would suggest looking into an intertial/accelerometer sensor. This not > only would be much more accurate, it would give you the added benefit of > 3d positioning. There are lots of reasonable priced ICs. Check out > Motorola low-g sensor ICs, like this one: > > http://e-www.motorola.com/brdata/PDFDB/docs/MMA1270D.pdf > http://e-www.motorola.com/brdata/PDFDB/docs/MMA1220D.pdf > > This one is only one dimension, but $20 from digikey. You can imagine > how to use 2 or 3 to get the other dimensions. There are also 2/3 d > varieties out there from other manufacturers but they tend to be pricey > and meant for higher gs. > > -Paul > > > > -----Original Message----- > > From: Steve Barr [mailto:] > > Sent: Thursday, May 29, 2003 5:24 PM > > To:
> > Subject: In-building location determination using wireless? > > > > > > Since GPS does not work indoors, I was looking into using > > an 802.11b network for location determination. > > > > Anyone know of something like this that's available > > for use? > > http://research.microsoft.com/~bahl/MS_Projects/projects.html#radar > > > > This project doesn't seem to be live: > > http://sourceforge.net/projects/locationserver/ > > > > Thanks! > > > > Steve > > -- > > http://www.stevebarr.com > > 100% my opinions. > > > > > > -- > > Subscription/unsubscription/info requests: send e-mail with subject of > > "subscribe", "unsubscribe", or "info" to
> > Wear-Hard Mailing List Archive (searchable): http://wearables.blu.org > > Please, *PLEASE* don't subscribe through a > > forward/expander/false domain > > > > - > > > > > > -- > Subscription/unsubscription/info requests: send e-mail with subject of > "subscribe", "unsubscribe", or "info" to
From Wear-Hard Mailing list Archive (WH)
Maintained by R. Paul McCarty
Archive created with babymail