Smoothing filter illustrated
I use a filter like this:

This will generate a signal output like this example:

In pseudocode

In a loop(DataChange for $Second for instance)

  m_dblSubtractionResult = m_dblSignalInput - m_dblDivisionResult
  m_dblAdditionResult = m_dblSubtractionResult + m_dblAdditionResult
  m_dblDivisionResult = m_dblAdditionResult / m_dblStabilizerSpeed

 m_dblDivisionResult  is the signal output

Here is a Visual Basic 6 sample program to illustrate.