can bluetooth do it ?

On Tue, 04 Apr 2006 03:57:04 -0700, wkulesza wrote:

> hey.
> i was looking on the web for answers but couldnt find any relevation
> info.
> i'm trying to find out if itt is technically possible for bluetooth
> technology to identify where do the found devices are ?
>
> say, using your cellphone, you look for bluetooth enabled phones in the
> room.
> you find 3 ppl that have bt turned on... can your phone "figure out"
> which phone belongs to whom? in other words, can the phone identify ppl
> like following? "patrick" is the first person from the right, and
> "kate" is the second person from the right ?
>
> thanx for any info or suggestions where to look for such information,
> regards,
> qlex

the simple answer is no. but read on!!!

BT devices have a name field which can be used as a personal tag, and if
all people in the room set the device name to their names you can get a
list of devices and thus you know who is present in the room. This is
basically the same as having a "computer name" in a LAN. Someone browsing
the LAN or the piconet in BT, sees a name rather than a MAC address. If
this field is not set all you see is a MAC address. Basically, you
associate a name to a MAC address (device serial number). Depending on
what you are using this field might be already set. Some mobile phones
set the device name to the brand name of the phone. PCs set it to the
computer name, etc.. In most of the cases you can change it to a text you
like.

As for location prediction. This is almost impossible. If you really want
to try, I can think of a very simple algorithm. Get the signal
strength of all devices in the room, this is easy to implement if you
know what you are doing. Presuming all of the devices suffer the same air
interference, using the signal strength you can predict who is nearest
and furthest to your BT device. ie, the stronger the signal, the closer
the person is.

The antennae in use is omnidirectional, so you have no clue of
direction, only a very rough and most probably inaccurate guess of
distance.

A starting point would be to get a book on BT and read the specs, you
can get the official BT specs from the internet, but the specs wouldnt be
very helpful for a beginner. For the implementation, I think, Win XP SP2
SDK which is free to download has a few samples on BT programming. If you
arent happy using Win XP and C programming, search the net for Bluetooth
SDKs, there might be some free Java libraries.