US Patent 7982989 Method and system for measuring magnetic interference width

A method for measuring a magnetic interference width for a magnetic recording head is described. The method includes writing a first track at a first frequency on a magnetic disk, writing a second track at the first frequency on the magnetic disk, and writing a third track at a second frequency on the magnetic disk between the first track and the second track. The third track partially overlaps both the first track and the second track and the second frequency is different from the first frequency. The method further includes measuring a readback profile across the first, second and third tracks on the magnetic disk.