Beacon feedback for isolation of carrier signal

A beacon antenna system comprising:

• a carrier signal generator configured to generate a carrier signal;
• a communication signal generator configured to generate a communication signal, the communication signal having a frequency that is offset from a frequency of the carrier signal;
• an antenna configured to produce an alternating current antenna signal comprising a carrier component derived from the carrier signal and a communication component derived from the communication signal;
• a mixer, configured to receive the carrier signal and the alternating current antenna signal and to generate a mixed signal comprising components corresponding to sums and differences of the carrier signal and the alternating current antenna signal;
• a filter configured remove components associated with the communication component from the mixed signal and produce a filtered feedback value representative of an amplitude of the carrier component;
• and
• a processor configured to adjust at least one drive parameter of the carrier signal generator based on the filtered feedback value.

A downhole beacon system for use in a horizontal directional drilling operation, comprising:

• a carrier signal generator configured to produce a carrier signal;
• a communication signal generator configured to produce a communication signal, in which a frequency of the communication signal is offset from a frequency of the carrier signal and combined with the carrier signal to form a beacon output;
• an antenna configured to transmit the beacon output to an above-ground location, the beacon output having a carrier component and a communication component;
• a mixer located in the downhole beacon and configured to mix the beacon output with the carrier signal to produce a mixed signal;
• a filter configured to receive the mixed signal and remove the communication component, and output a component indicative only of a carrier signal amplitude;
• and
• a controller configured to adjust at least one parameter of the carrier signal generator to maintain a consistent carrier signal amplitude.