Flux-gate magnetometer with drive signal for reducing effects of electromagnetic interference

• US 6,268,725 B1
• Filed: 04/29/1998
• Issued: 07/31/2001
• Est. Priority Date: 04/29/1998
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Tyler, Larry E., Vernon, Scott D.
• Primary Examiner(s): PATIDAR, JAY M
• Application Number:
  US09/069,472
• Time in Patent Office: 1,189 Days
• Field of Search: 324/244, 324/246, 324/247, 324/249, 324/251, 324/253, 324/254, 324/255-258, 324/225
• US Class Current: 324/253
• CPC Class Codes: G01R 33/04 using the flux-gate principle

Abstract

A flux-gate magnetometer having a drive signal for reducing the effects of electromagnetic interference (EMI) is provided. The drive signal has a characteristic that varies over time. For example, the drive signal may include a duty cycle that varies over time, the frequency of the drive signal may be varied over time, or the phase shift of the drive signal may vary over time.

Claims

1. A flux-gate magnetometer device for use in measuring an external magnetic field for providing measurement output, the device comprising:

at least one flux-gate sensor, a drive signal generator including means for dividing the frequency of the drive signal by two, resulting in a frequency divided drive signal and a non-frequency divided drive signal;

means for applying the frequency divided drive signal to at least one flux-gate signal;

translation means including means for controlling the inversion of the at least one sensor output signal based on the non-frequency divided drive signal resulting in a translated signal; and

means for filtering the translated signal to provide the measurement output.

2. The device of claim 1 wherein said translation means includes translation circuitry operably connected to the at least one flux-gate sensor to provide the measurement output representative of an external magnetic field based on the at least one sensor output signal.

3. The device of claim 2 wherein the translation circuitry includes means for measuring the duty cycle of the signal at the at least one flux-gate sensor.

4. The device of claim 1 wherein said translation means includes means for conditioning the sensor output signal to cancel common mode noise present at the sensors.

5. The device according to claim 1 wherein said translation means is connected to the at least one sensor to provide a measurement output representative of the external magnetic field based on the at least one sensor output signal.