Merging data sets

Let me outline the problem I am working with.   I have three different data aquisition systems that record various things.   Each one is logged at different timesteps throughout the day.    I would like to pull them into rapidminer individually and merge them into one dataset.   the problem I run into is that with the different spacing on the timestamp and different start times of each file.  What I want to do is take the higher speed data and average it over the timestep of the slowest speed data, and match the timesteps (or as close as possible) and then merge the three different sets of data into one.   I've been doing it outside of rapidminer in excel but I would prefer to do that in rapidminer and cut excel out of the process entirely..

any help is appreciated

thanks
Greg