The Roofing Filter Indicator was created by John Ehlers (“Cycle Analytics for Traders” pg. 80 – 82). When the indicator crosses over its signal then it is a short term uptrend and when it crosses below its signal then it is a short term downtrend. It is also in a major uptrend or downtrend when it is above 0 and below 0 respectively. Buy when the indicator line is green and sell when the indicator line turns red.