Marking tape with wire conductors and methods for use

A method of tracing a marking tape that is placed underground including the steps of:

• providing at least one pair of closely spaced, parallel conductors carried by and extending the length of the tape wherein the conductors are wires;
• providing at least one other insulated conductor carried by and extending the length of the tape and separated from said one pair of conductors at a distance that is greater than the distance between the conductors of said one pair of conductors;
• connecting said one pair of conductors and said one other conductor together at one end of the tape;
• applying an alternating current at a given frequency at the other end of said tape between at least one conductor of said one pair of conductors and said other conductor for establishing an electromagnetic field along said one pair of conductors and along said one other conductor;
• and
• moving a receiver having an antenna and capable of receiving said given frequency and communicating to an operator the strength of the received signal along the marking tape and swinging the receiver laterally of same to obtain a peak-null-peak signal as an indication that the operator is over the tape.

A method for tracing a marking tape that is placed underground and locating specific points along the marking tape includes the steps of:

• providing at least one pair of closely spaced, parallel conductors carried by and extending the length of the tape wherein the conductors are wires;
• providing at least one other insulated conductor carried by and extending the length of the tape and separated from said one pair of conductors at a distance that is greater than the distance between the conductors of said one pair of conductors;
• placing a passive marker at each specific point along the marking tape to be located subsequent to placement of the marking tape underground, said passive marker having an inductor-capacitor connected to form a resonant circuit of a selected frequency with said passive marker at each specific point along the marker placed to establish electromagnetic coupling with said one pair of conductors and with said other conductor;
• connecting said one pair of conductors and said one other conductor together at one end of the tape;
• applying an alternating current at said selected frequency at the other end of said tape between at least one conductor of said one pair of conductors and said other conductor for establishing an electromagnetic field along said one pair of conductors and along said one other conductor;
• and
• moving a receiver having an antenna and capable of receiving said given frequency and communicating to an operator the strength of the received signal along the marking tape and swinging the receiver laterally of same to obtain a peak-null-peak signal as an indication that the operator is over the tape and to obtain a signal in the region where there would be a null as an indication of the presence of said passive marker.

A method for determining the distance from a measuring point to a break in a marking tape that is placed underground including the steps of:

• providing at least one pair of closely spaced conductors carried by and extending the length of the tape, said pair of conductors presenting a known capacitance per unit length and wherein the conductors are wires that are severed when the marking tape is severed;
• measuring the capacitance presented by said pair of conductors when a break in the tape is known or suspected, such measurement being made from the end of said pair of conductors away from the known or suspected break in the tape;
• and
• calculating the distance from the point of measurement of the capacitance using the measured capacitance and the known capacitance per unit length of said pair of conductors.

A method of tracing a marking tape that is placed underground including the steps of:

• providing at least one current conducting path carried by and extending the length of the tape;
• providing at least one other current conducting path carried by and extending the length of the tape and spaced from said one current conducting path;
• connecting said one current conducting path and said other current conducting path together at one end of the tape;
• applying an alternating current at a given frequency at the other end of said tape between said one current conducting path and said other current conducting path for establishing an electromagnetic field along said one current conducting path and along said other current conducting path;
• and
• moving a receiver having an antenna and capable of receiving said given frequency and communicating to an operator the strength of the received signal along the marking tape and swinging the receiver laterally of same to obtain a peak-null-peak signal as an indication that the operator is over the tape.

A method for tracing a marking tape that is placed underground and locating specific points along the marking tape includes the steps of:

• providing at least one current conducting path carried by and extending the length of the tape;
• providing at least one other current conducting path carried by and extending the length of the tape and separated from said one current conducting path;
• placing a passive marker at each specific point along the marking tape to be located subsequent to placement of the marking tape underground, said passive marker having an inductor-capacitor connected to form a resonant circuit of a selected frequency with said passive marker at each specific point along the marker placed to establish electromagnetic coupling with said one current conducting path and with said other current conducting path;
• connecting said one current conducting path and said other current conducting path together at one end of the tape;
• applying an alternating current at said selected frequency at the other end of said tape between said one current conducting path and said other current conducting path for establishing an electromagnetic field along said one current conducting path and along said other current conducting path;
• and
• moving a receiver having an antenna and capable of receiving said given frequency and communicating to an operator the strength of the received signal along the marking tape and swinging the receiver laterally of same to obtain a peak-null-peak signal as an indication that the operator is over the tape and to obtain a signal in the region where there would be a null as an indication of the presence of said passive marker.