Solved

Does anyone have any resources or what algorithm to use for DTOA in a RTLS

Posted on 2008-10-22
3
300 Views
Last Modified: 2012-08-14
I have a project whereby I need to develop an application in java to calculate an RFID tagged object using DTOA (differential time of arrival) between four readers in a room. So when the tag beacons, it will hit each of the tags at different times and from that I need to calcuate the co-ordinates of the device. I am not looking for the code but an algorithm. Does anyone have any suggestions or resources?
0
Comment
Question by:jtiernan2008
  • 2
3 Comments
 
LVL 59

Expert Comment

by:Kevin Cross
ID: 22782403
This is probably not complete thought as have to figure out how to adjust the equations for non-linear travel to sensor (i.e. diagonal - being in a corner) but at least a start if a sensor reads time to hit each wall.

Assumptions:
Location on an axis W-E or N-S is expressed as a straight line from that wall.
West wall is 0 and East wall is full width of room (W).
North wall is 0 and South wall is full length of room (L).
Amount of time (N) that it takes to get a wall/sensor is equivalent to (time received - time sent) expressed in some time interval (t).  Nw = west wall, Ne = east wall, Nn = north wall, Ns = south wall.
There is a set rate of travel for a signal in this room expressed by distance over time interval (d/t).

So each of the coordinates x (W-E axis) and y (N-S axis) have two equations each.

x  = Nw * d/t
x = W - (Ne * d/t)
y = Nn * d/t
y = L - (Ns * d/t)

Solving for x and y will give you your (x, y) coordinate.

Just some thoughts -- hopefully not totally useless :).
0
 
LVL 59

Accepted Solution

by:
Kevin Cross earned 500 total points
ID: 22782418
And probably makes more sense for south wall to be 0, so that SW corner of your room is (0, 0) to make sense from a graph/grid perspective.  Then other distances will be expressed as positive (x, y) combinations from there.

What that changes is this:
x  = Nw * d/t
x = W - (Ne * d/t)
y = L - (Nn * d/t)
y = Ns * d/t
0
 
LVL 1

Author Closing Comment

by:jtiernan2008
ID: 31509017
This is pointing me in the right direction... thanks
0

Featured Post

Free camera licenses with purchase of My Cloud NAS

Milestone Arcus software is compatible with thousands of industry-leading cameras for added flexibility. Upon installation on your My Cloud NAS, you will receive two (2) camera licenses already enabled in the software. And for a limited time, get additional camera licenses FREE.

Join & Write a Comment

Today sees the launch of a new case study, focusing on BYOD technologies we have been working with for some time now.  But with the advent of 802.11ac wireless technologies and the story behind our landmark developments, we would like to share this …
Article by: Nicole
This is a research brief on the potential colonization of humans on Mars.
Viewers will learn about arithmetic and Boolean expressions in Java and the logical operators used to create Boolean expressions. We will cover the symbols used for arithmetic expressions and define each logical operator and how to use them in Boole…
The viewer will learn how to implement Singleton Design Pattern in Java.

757 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

18 Experts available now in Live!

Get 1:1 Help Now