Re: RFID tracking and gumstix

> 1. You probably have a serious multipath environment which will make 
> triangulation a pain (Not only triangulation, every kind of transmision)


How does 802.11b deal with multi-path?
I witnessed real projects in 99' doing 802.11b location sensing.

The antenna is high power, the collar is low power.  You control which area 
of potential collars you talk to.
Say alternate scanning mutually exclusive zones, which would require 
coordinated communications between gumstix.

> 2. The space is confined which means that small errors in the 
> triangulation will introduce large errors in the position.

Well whatever the solution, it would need to scale up to 200 acres.
This may require some form of compromise for a small area.

> 3. The problem is not about tracking ONE ape...it is about tracking N 
> apes. So triangulation using a Bluetooth device (non modified that is) is 
> out of the question as you can not tell which transmiter is the one you 
> are trying to triangulate (please correct my ignorance on this, if any)


Yes if everyone tried talking at once it would be a mess.

> 4. Having the colars waking up and transmiting introduces the problem of 
> colisions which gets more significant as the number of colars increases.


The goal of the entire system would be to minimize the rf chatter.
Keep in mind the collars would be low power, so they number of arbiters 
would be low.
After they get their message off, they go back to sleep.  Bluetooth has 
arbitration built in.

> 5. If you fill the place with a network of underground computers, the cost 
> is going to be high for both installation AND maintainance.....which is ok 
> if your budget allows it.


The gumstix would be associated with the antenna.  The gumstix has the 
ability to log data to removable storage.

> 6. Puting a gumstix on the colar of the ape seems attractive to your 
> application, so lets take it from there.

Are any sleep features of the PXA255 supported in the current software?
As running a 200MHz PXA255 full speed on batteries wouldn't last all day.

Cheers,
Joel 




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