Electromagnetic receiver tracking and real-time calibration system and method

1. An electromagnetic (EM) system for measuring EM signals, the EM system comprising:

a survey EM transmitter for generating survey EM signals within a first frequency range;

a calibration EM transmitter for generating a calibration signal;

a receiver section, including a receiver housing and a receiver, that measures both the survey EM signals and the calibration signal; and

a calibration device connected to the calibration EM transmitter and to the receiver, the calibration device configured to control a frequency and waveform of the calibration signal,

wherein the calibration device is further configured to calculate a response function of the receiver, based on the calibration signal.

2. The system of claim 1 , wherein the calibration device includes a controller and the controller is configured to subtract the response function of the receiver from the measured survey EM signals.

3. The system of claim 1 , wherein the calibration device is located on a reference frame to which the receiver housing is connected to with a connecting mechanism.

4. The system of claim 1 , wherein the calibration device is located on the receiver housing.

5. The system of claim 1 , further comprising:

a tracking EM transmitter for generating tracking signals within a second frequency range,

wherein the receiver section is configured to measure the tracking signals.

6. The system of claim 5 , wherein the calibration device is integrated inside the tracking EM transmitter.

7. The system of claim 5 , wherein the receiver includes three mutually orthogonal coils, each independently measuring each of the tracking signals.

8. The system of claim 1 , wherein the calibration signal is emitted during an ON-time of the survey EM signals.

9. The system of claim 1 , wherein the calibration signal has a different frequency for each ON-time cycle of the survey EM signals.

10. The system of claim 1 , wherein the calibration signal has a frequency that is a harmonic of a frequency of the survey EM signals.

11. An electromagnetic (EM) system for measuring EM signals, the EM system comprising:

a transmitter section;

a receiver section;

a calibration device configured to control a frequency and waveform of a calibration signal; and

a tow assembly connecting the transmitter section and the receiver section to an aircraft,

wherein the transmitter section includes a survey EM transmitter for generating survey EM signals within a first frequency range, and a calibration EM transmitter for generating the calibration signal,

wherein the receiver section includes a receiver housing and a receiver that measures both the survey EM signals and the calibration signal, and

wherein the calibration device is further configured to calculate a response function of the receiver, based on the calibration signal.

12. The system of claim 11 , wherein the calibration device includes a controller and the controller is configured to subtract the response function of the receiver from the measured survey EM signals.

13. The system of claim 11 , wherein the calibration device is located on a reference frame to which the receiver housing is connected to with a connecting mechanism.

14. The system of claim 11 , wherein the calibration device is located on the receiver housing.

15. The system of claim 11 , further comprising:

a tracking EM transmitter for generating tracking signals within a second frequency range,

wherein the receiver section is configured to measure the tracking signals.

16. The system of claim 15 , wherein the calibration device is integrated inside the tracking EM transmitter.

17. The system of claim 11 , wherein the calibration signal is emitted during an ON-time of the survey EM signals.

18. The system of claim 11 , wherein the calibration signal has a different frequency for each ON-time cycle of the survey EM signals and the calibration signal has a frequency that is a harmonic of a frequency of the survey EM signals.

19. A method for calibrating an electromagnetic (EM) receiver, the method comprising:

generating a calibration signal with a calibration device;

applying the calibration signal to a receiver;

measuring a voltage across the receiver to determine a response function of the receiver;

generating survey EM signals with a survey EM transmitter;

measuring with the receiver the survey EM signals; and

calibrating the receiver based on the response function.

20. The method of claim 19 , further comprising:

subtracting the response function from the measured EM signals.