The team I'm working with is trying to design a position finding system that would work in an area with a 25m radius with a relatively high resolution. What I've determined is that to get the most accurate results you want to do this with a ping (i.e. not using signal strength).
We've looked at using an ultrasonic pulse, but it has distance limitations and in particular the system is meant to be in someone's yard so those might bug animals.
The idea I'm on right now is that whatever object is tracking, we place an RFID tag on them. We can then triangulate the position by sending an RF signal, and timing the delay from sending the signal to getting a response from the RFID tag. To get accurate results we'd need to be able to measure the delay to the nearest ns or better. If the timer is accurate to the nearest ns, that would tell us the distance within .15m of the RFID tag which would be acceptable. Are there any timers out there that has this level of accuracy?
Also I found a patent for a system using a similar method here: http://www.freepatentsonline.com/5828443.pdf.
My only concern is that the counter we'd need to use would run at 1GHz, but we want to keep the cost down low (that's if we can even find such a counter).
We've looked at using an ultrasonic pulse, but it has distance limitations and in particular the system is meant to be in someone's yard so those might bug animals.
The idea I'm on right now is that whatever object is tracking, we place an RFID tag on them. We can then triangulate the position by sending an RF signal, and timing the delay from sending the signal to getting a response from the RFID tag. To get accurate results we'd need to be able to measure the delay to the nearest ns or better. If the timer is accurate to the nearest ns, that would tell us the distance within .15m of the RFID tag which would be acceptable. Are there any timers out there that has this level of accuracy?
Also I found a patent for a system using a similar method here: http://www.freepatentsonline.com/5828443.pdf.
My only concern is that the counter we'd need to use would run at 1GHz, but we want to keep the cost down low (that's if we can even find such a counter).