High-Q self tuning locating transmitter

A human-portable transmitter apparatus for generating an output signal having a frequency fR suitable for inducing an alternating electrical current in a buried conductor, the transmitter apparatus comprising:

• a User Interface (UI) for accepting operator commands;
• a controller coupled to the UI for selecting a desired output signal frequency value fR1 responsive to an operator command;
• an exciter circuit coupled to the controller for generating an excitation signal having a frequency corresponding to the desired output signal frequency value fR1;
• an electrical resonator coupled to the exciter circuit and having a primary resonant frequency value fR, including
• a capacitor assembly having a capacitance value C, and
• a plurality of conductors having a aggregate inductance value L and disposed in connection with the capacitor assembly to provide the primary resonant frequency value fR;
• and
• an adaptive tuner coupled to the controller and the electrical resonator that adjusts the number of conductor turns coupled to the capacitor assembly responsive to the difference between the desired output signal frequency value fR1 and the primary resonant frequency value fR, thereby obtaining the inductance value L necessary to produce a high Quality Factor (Q) output signal having the desired frequency value.

A human-portable transmitter apparatus for generating an output signal having a frequency suitable for inducing an alternating electrical current in a buried conductor, the transmitter apparatus comprising:

• a User Interface (UI) for accepting operator commands;
• a controller coupled to the UI for selecting a desired output signal frequency value fR1 responsive to an operator command;
• an exciter circuit coupled to the controller for generating an excitation signal having a frequency corresponding to the desired output signal frequency value fR1;
• an electrical resonator coupled to the exciter circuit and having a primary resonant frequency value fR;
• the electrical resonator including:
• a conductor assembly having an aggregate inductance value L, and
• a plurality of capacitors having an aggregate capacitance value C and disposed in connection with the conductor assembly to provide the primary resonant frequency value fR,
• at least one conductive coil in the conductor assembly defining a low-permeability core volume, wherein at least half of the transmitter apparatus elements are disposed outside of the low-permeability core volume during operation of the transmitter apparatus;
• and
• a substantially non-conductive, non-magnetic case enclosing at least the majority of the transmitter apparatus elements including the electrical resonator.