Noise emission is often considered to be one of the major drawbacks of fluid power systems. One of the main sources of noise is flow ripple caused by positive displacement pumps. This paper is concerned with the problems of modelling and measurement of flow ripple with emphasis on analyses with theoretical techniques.A simulation model of a piston pump has been used in this investigation. Simulation has proved to be a useful tool for optimization of the portplate geometry and for developing new methods to reduce pump flow ripple. Different conventional methods are compared with unconventional ones. A new method which gives very low flow ripple over a large operating range is included in this study.