Measure distance between 2 devices

Hi there, I’m a freshman at a university of technology and i have absolutely no idea what i am doing (: I’m trying to find out if there’s any way we can measure the distance between 2 devices. We only need to know if its far, near-ish or super close. We’ve looked into bluetooth, RSSI and XBee, but than again we have no clue. Please help us (:

A tape measure is cheap and reliable.

As to using RF search the forums here since this has been asked and discussed many, many times.

Carola:
Hi there, I’m a freshman at a university of technology and i have absolutely no idea what i am doing (: I’m trying to find out if there’s any way we can measure the distance between 2 devices. We only need to know if its far, near-ish or super close. We’ve looked into bluetooth, RSSI and XBee, but than again we have no clue. Please help us (:

Via RF means, it is very expensive. Read about time difference of arrival and trilateration.

If it’s range only (distance), not location, then consider radar-like approaches using ultrasonics or laser. Robotics hobby folks use off the shelf ultrasonic ranging devices, good to about 8 ft.

This topic has been discussed widely for years, so do some research and reading about the underlying physics.