Saturday, May 16, 2009
Week 4 Journal (Practical Session)
This week consists of only the practical session. Early in the morning, we reported at the FrontlineAeroscout Centre. The activity we are handling are active tags by Aeroscout.
Active Aeroscout Tag
Active tags are RFID tags that are battery powered and have life span based on the battery life. It is more expensive than passive tag and is larger in size. However, it has longer range of operation up to 1.5km in open-field.
During the practical session, we learnt to implement a tracking system to track outdoor assets using RFID technology. Mr Peter taught us in how to use Time Difference of Arrival (TDOA) algoritm to determine the location of the outdoor assets.
Time Difference of Arrival
An example of application using such technology is the tracking of cars in a carpark. As extracted from the practical.
- A brand new car from the manufacturing plant is unloaded from a trunk
- Car's ID number and bar-coded instructions pertaining to the details of this car is scanned into an RFID tag which is hung on the car's rear-view mirror
- Car is move to a vacant parking lot
- The location receivers read the tag and reflect the exact car location on the map at the self-service kiosk
Sample Aeroscout Tag Manager Interface
I have also learnt that TDOA method requires at least 3 location receivers. In addition, it requires prior calibration and the location receivers' clock must be synchronized. As time was limited, Mr Peter demonstrated all the steps and we listened. What we have really done is to carry the tag and move it from one position to another. What has really amazes me is that the system is able to detect the location of the tag. The system will indicate the tag movement whenever we move around.