Range Finder
I need to implement a circuit to measure distances using any kind of wireless technology. I already searched for anything similar to a sonar or a parking aid (with infrared or ultrasound) but I only get distances up to 10 meter and I need a bit more. Also I need to get a linear output so I can interface it with a seven segment display and usually the output is a counter and some LEDs.
Does anyone have this kind of circuit around?
you should specify your range of intrest for measuring and the precision you need!
maybe if you use laser type range finder it would be better and more precised!
Well, these are the difficult questions to answer. I have been debating with them myself.
I would like to have something around 50 meter within 1 meter precison. But I'm on a tight budget so I think that laser is out of the scope.
I have been looking around for some technologies to do this namely:
Laser - Too expensive. Also I think that measuring 50 meter will be difficult to capture the reflexion.
Infrared - Good but only on the 10 meter range. Also, it gets very attenuated on reflexions.
UltraSound - It seems the best option, because of the budget, but not good enough for 50 meter because of ghost reflexions.
With all these limitations I don't know if this is really feasible. Am I right?
Laser looks as best option, and you can improve sensitivity of receiver by modulating laser output and build frequency selective receiver. There are integrated solutions that do this and laser does not have to be expensive, even keychain laser might do for your purpose. On receiving end measure phase and you should be able to get better than 2% accuracy on 50 meters.
So laser it is...
Does someone have this kind of schematic around?
Thanks.
Mmmm, the laser based i have seen costs 2K usd. I dont remember exact web address, it was on some of robotic part sailing sites and produced by japan company.
For ultrasound you can try to use narrow beam shaped sensors (7 - 15 degree) but those are expensive (more than 40 -100 Euro per pcs) or use inphase modulated low cost ultrasound sensors array to get narrow beam shape and increased sound pressure level. You have to experiment .
BTW 1 meter or 3 nanosec resolution isnt much hard for laser based measurement but where to find optics ?
And you dont need radar based ultrasound measurement if receiver can be mounted on object to measure distance to .