Measuring the distance between two objects

Hello,

I'm starting a project that heavily relies on the ability to determine the distance between two objects. The aim of the project is to reliably calculate distances of up to 300 yards, and as little as 3 feet.

One object is mobile (handheld), and the other is fixed. Both objects may have hardware, with the handheld one displaying the distance. The hardware attached to the fixed object would hopefully be passive/less expensive as it would be more vulnerable to theft. The measurements should be precise within 3 yards when you are father away (upwards of 20 yards), but of course much more precise when you are within 20 yards (to a precision of approximately 1 foot). It is essential that multiple handheld devices can measure their respective distances to the fixed object without interference.

Any ideas and resources would be greatly appreciated. We're looking to make a device that is relatively easy to use (point and click preferably). We are also trying to keep our costs relatively low, so no military-grade laser-range-finder-ideas please and thank you. I am available to give more information if needed, so please just ask.

Thank you for your time,
Michelle

Perhaps one of these golf distance measuring devices could be adapted to your use.

Following Carl's suggestion I would propose for your fixed device to be nothing but coordinates preset on the hand-held built around a GPS module.

Mike