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 tracking reference frame;

a tracking EM transmitter for generating tracking signals within a second frequency range, wherein the tracking EM transmitter is rigidly attached to the tracking reference frame; and

a receiver section including a receiver housing and a receiver that measures both the survey EM signals and the tracking signals,

wherein the receiver housing is attached with a connecting mechanism to the tracking reference frame so that the receiver housing freely translates and rotates in all directions.

2. The system of claim 1 , further comprising:

a controller connected to the receiver and configured to calculate a position and orientation of the receiver relative to the tracking EM transmitter based on the recorded tracking signals.

3. The system of claim 2 , further comprising:

a global positioning system connected to the controller and configured to provide a location of the tracking EM transmitter relative to ground,

wherein the controller calculates a location and orientation of the receiver relative to ground based on information from the global positioning system and the tracking signals.

4. The system of claim 1 , wherein the first frequency range is different from the second frequency range.

5. The system of claim 1 , wherein the second frequency range is within the first frequency range.

6. The system of claim 1 , wherein the receiver measures the survey EM signals during an OFF-time period and the tracking signals during an ON-time period.

7. The system of claim 1 , wherein the receiver measures the survey EM signals during an entire OFF-time period while measuring the tracking signals during a portion of the OFF-time period.

8. The system of claim 7 , wherein the portion of the OFF-time period is 20% or less than the entire OFF-time period.

9. The system of claim 1 , wherein the receiver section is free to rotate and translate relative to the tracking EM transmitter.

10. The system of claim 1 , wherein a distance between the receiver and the tracking EM transmitter is smaller than a radius of the survey transmitter.

11. The system of claim 1 , wherein the measured tracking signals propagate directly from the tracking EM transmitter to the receivers.

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

an aircraft;

a transmitter section;

a receiver section;

a tracking reference frame; and

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

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

a tracking EM transmitter for generating tracking signals within a second frequency range, wherein the tracking EM transmitter is rigidly attached to the tracking reference frame; and

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

wherein the receiver housing is attached with a connecting mechanism to the tracking reference frame so that the receiver housing freely translates and rotates in all directions.

13. The system of claim 12 , further comprising:

a controller connected to the receiver and configured to calculate a position and orientation of the receiver relative to the tracking EM transmitter based on the recorded tracking signals.

14. The system of claim 13 , further comprising:

a global positioning system connected to the controller and configured to provide a location of the tracking EM transmitter relative to ground,

wherein the controller calculates a location and orientation of the receiver relative to ground based on information from the global positioning system and the tracking signals.

15. The system of claim 13 , wherein the receiver measures the survey EM signals during an entire OFF-time period while measuring the tracking signals during a portion of the OFF-time period.

16. A method for determining the position and/or orientation of an electromagnetic (EM) receiver, the method comprising:

crossing a given exploration area with a transmitter section, wherein the transmitter section includes a survey EM transmitter for generating survey EM signals within a first frequency range and a tracking EM transmitter for generating tracking signals within a second frequency range, wherein the tracking EM transmitter is rigidly attached to a tracking reference frame; and

recording with a receiver section including a receiver housing and a receiver, both the survey EM signals and the tracking signals,

wherein the receiver housing is attached with a connecting mechanism to the tracking reference frame so that the receiver housing freely translates and rotates in all directions.

17. The method of claim 16 , further comprising:

calculating in a controller a position and/or orientation of the receiver relative to the tracking EM transmitter based on the recorded tracking signals.

18. The method of claim 17 , further comprising:

receiving from a global positioning system, connected to the controller, a location of the tracking EM transmitter relative to ground; and

calculating a location and orientation of the receiver relative to ground based on the global positioning system and the recorded tracking signals.

19. The method of claim 16 , wherein the measured survey EM signals and the measured tracking signals have different frequencies.

20. The method of claim 16 , wherein the receiver measures the survey EM signals during an entire OFF-time period while measuring the tracking signals during a portion of the OFF-time period.