TACAN bearing system works in a similar way to a VOR by sending out multiple signals from which the receiver can determine the radial by measuring the phase difference in the signals. However, the TACAN's phase difference is repated every 40 degrees thus making it (in theory) nine times more accurate. This is acheived by a rotating drum and reflectors and is the size of a largish dutbin, thus is much slmaller and portable compared with a VOR. It can also be installed on a ship.