> Anyone know of any ICs designed for measureing distances with RF? I'm thinking in terms of 10 feet, 100 ft, and 500 feet with resolution to one foot. The basic method of one device emitting a signal and another echoeing it back would be attractive.
>    Any recommendations?
> 
> Hul   



Dunno about ic's, but I would look at 10 GHz gunn diode intruder
alarm modules as a starting point. They normally work on the doppler
principle, but could be pulse modulated for ranging work. Probably
need a better horn antenna, so you may need to find some with X band
flange interface. They are cheap, proven tech and easy to get started
experimenting with. Also similar tech modules at 35GHz or so.

Ultrasonics would be hard work at 500 Mtrs and would need significant
power, even if it could be made to work at all...

Chris