Apparatus for identifying a marker

摘要

The invention provides an interactive means to locate and identify underground utilities. The apparatus is used with a marker associated with an elongate electrical conductor (42), which may be a cable shield or a trace wire. It includes a remote, portable probe (10) that is used to transmit a RF signal to be received by a transponder (26) associated with the marker. The transponder (26) is powered by a DC potential on the conductor (42). In preferred embodiments the transponder (26) has the capability of communicating with a terminal unit (46) over the conductor (42) to transmit information and instructions between the probe (10) and the terminal unit (46). <IMAGE>