exactOutdoor locator bracelet

[patrick707]

Can I design an infrared radio-enabled tracking device combined with a mobile application, the radio chip within the Bracelet constantly communicates with the mobile device and positions other users within a private group on a 360 degrees radar screen app

How expensive will it be and what technologies do you propose to locate people with a 400 m radius.

 

[Comcokid]

I saw applications like this demonstrated with 802.15.4 type devices 8 to 10 years ago. The 802.15.4 (physical layer designation) is sometimes talked about as Zigbee (app layer). They self-form adaptive mesh networks and can measure and pass timing and signal strength data to a central host (PC) to display a virtual map of where the devices are. There a measurement uncertainties with this such as variations in signal time-of-flight (bulk dielectric objects that may slow down signals like people large trees), reflections that delay signals, etc.

Just saying I've seen demonstrations and not saying 802.15.4 is necessarily the way to go. Over a 400 m range devices with a little higher rf power would be required to give coverage, but then again I've seen special modules that had max 1 mile range with embedded antennas.

 

[IRstuff]

The high-end Zigbees supposedly have a max range of 1 mile, so that could be coupled with with GPS to get the positioning accuracy better. Or, if this is a cooperative scenario, it might be easier to just get all these people a \phone app like:

https://play.google.com/store/apps/details?id=com.fsp.android.friendlocator&hl=en

However, 400m is not exactly a long distance, so what prevents direct line of sight?

TTFN
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Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com:

http://www.engineering.com/AskForum/aff/32.aspx

 

[MacGyverS2000]

You COULD use IR, but that assume LOS all (most?) of the time. If you're trying to locate people in a crowd, in a forest/cave, etc., you'll likely have too little contact between units to make a meaningful database.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[VEBill]

We've had multiple threads over the years on the subject of short range, often indoors, highly accurate positioning systems.

To my recollection, there's never been an obvious slam-dunk solution.