BBTrend is a relatively new indicator developed by John Bollinger to work with Bollinger Bands™. It is one of only a few indicators that can signal both strength and direction making it a very valuable tool for traders.
The calculations are fairly simple. The default periods of 20 and 50 are shown, but these can be changed through the parameters.
Lower = MathAbs(lowerBB(20) – lowerBB(50))
Upper = MathAbs(upperBB(20) – upperBB(50))