Ultrasonic module for distance measurement between pairs?

[allanw]

Does anyone know any commercial solutions for determining the range between two objects using an ultrasonic sensor mounted on each? Ideally it'd be small and integrated (ie, with PCB all ready to go) and sense with a range between 1" to 3 feet. Also, I'd need it to have a wide angle, like an entire hemisphere. I was thinking if one ultrasonic transducer were to transmit in all directions, the second one could pick up the signal as long as it was anywhere in its line of sight. Both would be synchronized by the same microcontroller, so that the timing between the send and receive could be used to determine distance. I'm just not sure what to search to find products like this.

Or alternatively, I'd like to know about any other commercially available solutions for measuring the distance between two moving objects.

[joelby]

I don't know if there's an off-the-shelf version, but I once read an interesting paper on doing this using only standard Windows Mobile devices: http://portal.acm.org/citation.cfm?id=1322265

Let me know if you don't have access to the ACM Digital Library.

[saturation]

Radar could work, measure the doppler shift, you need only one unit.  You can get kits:

http://store.qkits.com/moreinfo.cfm/VM125

and take it from there; the output may be accurate enough for your needs.

To measure only two objects just increase the radar signature of the other, so it predominates the area.

Does anyone know any commercial solutions for determining the range between two objects using an ultrasonic sensor mounted on each? Ideally it'd be small and integrated (ie, with PCB all ready to go) and sense with a range between 1" to 3 feet. Also, I'd need it to have a wide angle, like an entire hemisphere. I was thinking if one ultrasonic transducer were to transmit in all directions, the second one could pick up the signal as long as it was anywhere in its line of sight. Both would be synchronized by the same microcontroller, so that the timing between the send and receive could be used to determine distance. I'm just not sure what to search to find products like this.

Or alternatively, I'd like to know about any other commercially available solutions for measuring the distance between two moving objects.

[Mechatrommer]

maybe you can modify this? http://cgi.ebay.co.uk/Ultrasound-Motion-Sensor-Robotic-Basic-Stamp-/350360926557?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item519323795d

[Bruwer]

Try:
www.maxbotix.com

They specialise in sonar items.