Laboratory experiments have been performed on medium sized roller bearings with two levels of artificial damage. Recordings of long time series have been made from both accelerometers and acoustic emission sensors at a wide range of different radial loads and rotation speeds. Due to non-perfect performance of the control systems for the rotation speed or frequency, significant variations were observed at all rotation speeds, and highest relative variation at the lowest rotation speeds. These variations were also recorded using a rotary encoder (tachometer). In real life condition monitoring, tachometers or rotary encoders are not always present, this can be due to the cost of installation or space limitations for introducing additional sensors. The present work describes the results of applying different methods for order tracking or correction for variations of instantaneous frequency without relying on the rotary encoder. These results are then verified by comparison to the rotary encoder data.