A system for measuring distance between a first locus and a second locus includes:
(a) at least one beacon device; a respective beacon device of the at least one
beacon device being situated at the first locus and transmitting a respective electromagnetic
signal; and (b) at least one locator device; a respective locator device of the
at least one locator device being situated at the second locus and receiving the
respective electromagnetic signal. The respective locator device is situated at
a distance from the respective beacon device within near-field range of the respective
electromagnetic signal. The respective locator device distinguishes at least two
characteristics of the respective electromagnetic signal. The respective locator
device employs the at least two characteristics to effect the measuring.