Method and apparatus for position and motion sensing

A method for separating information representing position from information representing activity in a digitized composite signal, said method comprising:

• low pass filtering said digitized composite signal to produce a first filtered signal, said low pass filtering passing a first frequency range;
• narrow-band low pass filtering said digitized composite signal to produce a second filtered signal, said narrow-band low pass filtering passing a second frequency range, said second frequency range being narrower than said first frequency range and comprising at least a part of said first frequency range, wherein said second filtered signal includes said information representing position;
• and
• subtracting said second filtered signal from said first filtered signal to produce a difference signal, wherein said difference signal includes information representing activity.