Ranging to an electromagnetic target without timing

A method for magnetic ranging comprising:

• (a) automatically switching an electromagnet deployed in a target wellbore back and forth between at least first and second states;
• (b) acquiring a plurality of x-axis, y-axis, and z-axis magnetic field measurements using a tri-axial magnetic field sensor deployed on a drill string in a drilling wellbore while the electromagnet is automatically switching in (a);
• (c) sorting the plurality of x-axis magnetic field measurements into at least first and second sets of x-axis measurements corresponding to the first and second states of the electromagnet;
• (d) sorting the plurality of y-axis magnetic field measurements into at least first and second sets of y-axis measurements corresponding to the first and second states of the electromagnet;
• (e) sorting the plurality of z-axis magnetic field measurements into at least first and second sets of z-axis measurements corresponding to the first and second states of the electromagnet;
• and
• processing the first and second sets of x-axis, y-axis, and z-axis magnetic field measurements to compute at least one of a distance and a direction from the drilling well to the target.