Operational Modal Analysis consists on estimate the modal parameters (natural frequencies, damping ratios and mode shapes) from ambient vibration measurements. The most common situation is to analyze a single time series of acceleration data, but there may be situations where you have more than one time series or multiple records. For example

1. Different exitacion sources are considered: ambient loading, a hammer, a shaker,...

2. The structure has permanent sensors installed on it.

3. Different setups of sensors are used to estimate partial mode shapes. These setups share some sensors in common what are used to merge or glue the partial mode shapes to obtain global mode shapes.

In this work we propose to use the Espectation Maximization algorithm to estimate the modal parameters of the structure. The advantage of using this method is that we can process all the time series at the same time, obtaining a single estimation for each modal parameter. The method is tested with both numerical and real measured data.