While some encoders (AS5040, AS5134) have UVW outputs that allow 1:1 replacement of the conventional three Hall switches, the encoder can do even more. A common problem with BLDC motors is the weak torque at start-up, especially when using sensor-less controllers (using back-EMF for position calculation). To overcome this problem, Hall switches in combination with large pole count rotors are implemented. This improves the start-up torque, but the problem with torque ripple (fluctuating torque) remains. This generates more audible noise, more reactive power (which equals more heat) and simply less battery life, for example with battery power tools. The best method to get rid of all these problems is to use sinusoidal commutation (apply three phase shifted sine waves to the stator as opposed to switching the coils on and off). An improved form of sinusoidal commutation is called FOC, or field-oriented-control. This method provides not only constant torque at any angle and speed, it also allows speed and torque to be adjusted independently from each other. FOC requires a high resolution absolute encoder position feedback. This can be solved best with magnetic encoders. Absolute optical encoders or resolvers are too expensive and Hall switches are not accurate enough.