Magnetic detector

1. A probe for detecting a magnetic marker comprising:

a probe core having a first end and a second end, the probe core defining two regions for containing coils of wire, one of the regions being adjacent the first end of the cylindrical probe core;

two sense coils, one each of the sense coils being located in a respective one of the regions; and

two drive coils, one each of the drive coils being located in a respective one of the regions,

wherein the regions are separated by a distance equal to or greater than the diameter of one of the coils,

wherein the regions of the probe define four channels for containing coils of wire, a respective two of the channels being located in each of the respective regions,

wherein two of the channels are located adjacent the first end of the cylindrical probe core,

wherein one each of the sense coils being located in a respective one of the channels in each one of the regions,

wherein one each of the drive coils being located in a respective one of the channel in each one of the regions,

wherein no two coils occupy the same channel,

wherein the drive coils are connected in series, and

wherein the sense coils are connected in anti-series.

2. The probe of claim 1 wherein the order of the coils from the first end toward the second end of the probe is sense coil, drive coil, sense coil, and drive coil.

3. The probe of claim 1 wherein the order of the coils from the first end toward the second end of the probe is drive coil, sense coil, drive coil, and sense coil.

4. The probe of claim 1 wherein the order of the coils from the first end toward the second end of the probe is sense coil, drive coil, drive coil, and sense coil.

5. The probe of claim 1 wherein the order of the coils from the first end toward the second end of the probe is drive coil, sense coil, sense coil, and drive coil.

6. A probe for detecting a magnetic marker comprising:

a probe core having a first end and a second end, the probe core defining two regions for containing coils of wire, one of the regions being adjacent the first end of the cylindrical probe core;

two sense coils, one each of the sense coils being located in a respective one of the regions; and

two drive coils, one each of the drive coils being located in a respective one of the regions,

wherein the regions are separated by a distance equal to or greater than the diameter of one of the coils,

wherein the regions of the probe define four channels for containing coils of wire, a respective two of the channels being located in each of the respective regions,

wherein two of the channels are located adjacent the first end of the cylindrical probe core,

wherein one each of the sense coils being located in a respective one of the channels in each one of the regions,

wherein one each of the drive coils being located in a respective one of the channel in each one of the regions,

wherein no two coils occupy the same channel,

wherein the drive coils are connected in anti-series, and

wherein the sense coils are connected in series.

7. The probe of claim 6 wherein the order of the coils from the first end toward the second end of the probe is sense coil, drive coil, sense coil, and drive coil.

8. The probe of claim 6 wherein the order of the coils from the first end toward the second end of the probe is drive coil, sense coil, drive coil, and sense coil.

9. The probe of claim 6 wherein the order of the coils from the first end toward the second end of the probe is sense coil, drive coil, drive coil, and sense coil.

10. The probe of claim 6 wherein the order of the coils from the first end toward the second end of the probe is drive coil, sense coil, sense coil, and drive coil.