Envelope Channels

Envelope Channels are percentage-based envelopes set above and below a moving average. The moving average, which forms the base for this indicator, can be a simple, exponential, front-weighted or Hull moving average. The top and bottom channel lines are plotted the same percentage above or below the moving average. This creates parallel bands that follow price action. With a moving average as the base, Moving Average Envelopes can be used as a trend following indicator. However, this indicator is not limited to just trend following. The envelopes can also be used to identify overbought and oversold levels when the trend is relatively flat.

You are not limited to plotting envelope channels on price.  They can also be plotted on any other indicator on the chart and will use the indicator as the basis for the moving average calculation instead of price.

If you want to see the moving average used to calculate the channels, select the Plot Center Line option. 

Custom PCF Formula
Of Price Top (1 + w / 100) * tAVGCx.z
 t=AverageType, w=Width(%), x=Period, z=Offset
Bottom (1 - w / 100) * tAVGCx.z
Center tAVGCx.z
Width w / 50 * tAVGCx.z
Generalized Version Top (1 + w / 100) * tAVG(v, x)
 t=AverageType, w=Width(%), x=Period, v=Numeric
Bottom (1 - w / 100) * tAVG(v, x)
Center tAVG(v, x)
Width w / 50 * AVG(v, x)

Where t is the Average Type. Leave blank for Simple, X for Exponential, F for Front Weighted, and H for Hull.

Where w is the Width (%) setting.

Where x is the Period which must be an integer.

Where z is the Offset. An offset of 1 would be 1 bar ago.

Where v is any formula returning a numeric value.

Examples

The top simple Envelope Channel 20, 2.00 can be written as follows.

(1 + 2 / 100) * AVGC20

The bottom simple Envelope Channel 20, 2.00 can be written as follows.

(1 - 2 / 100) * AVGC20

The center simple Envelope Channel 20, 2.00 is just the 20 period simple moving average.

AVGC20

Read more about Envelope Channels on Investopedia.