To use this technique you require 3 inputs. GAV stands for Gann angle and volatility trade technique.

a. Daily volatility (DV) of the instrument (the instrument is either equity or future or commodity not the option)

b. Opening price of the instrument

c. Previous closing price of the instrument.

Trader need to calculate the price range
Price range calculation formula

Price Range = Daily volatility * previous closing price.
If the daily volatility is in the percentage form then do not forgot to divide the result by 100.
Example 1: Nifty on 18th March 2015 open at 8775, its daily volatility is 0.96 and previous close is 8740.
Price range = (8775 *0.96)/100=84.25

Understand the 11 Gann trend lines
Now the 11 sets of trend lines from a lower price point towards the higher price point are as follows

1X1, 1X2, 2X1, 1X3, 3X1, 1X4, 4X1, 1X8, 8X1, 1X16 and 16X1.

The geometrical angle made by these trend lines with the X axis in an up move

(i.e. if the trident line will be drawn from a major low or intraday low)

corresponding to 2X1= 63.75 degrees, 1X2= 26.25 degrees, 1X1= 45 degrees, 1X3= 18.75 degrees, 3X1= 71.25

degrees, 4X1= 75 degrees, 1X4= 15 degrees, 8X1= 82.5 degrees, 1X8= 7.5 degrees, 1X16= 3.75 degrees, 16X1= 86.25 degrees.

The geometrical angle made by these trend lines with the X axis in a down move

(i.e. if the trident line will be drawn from a major high or intraday high)

corresponding to 1X2= 63.75 degrees, 2X1= 26.25 degrees, 1X1= 45 degrees, 3X1= 18.75 degrees, 1X3= 71.25 degrees, 1X4= 75 degrees, 4X1= 15 degrees, 1X8= 82.5 degrees, 8X1= 7.5 degrees, 16X1= 3.75 degrees, 1X16= 86.25 degrees.