Algorithm 1:

Require: 1 × 9 VRF signal array, $x\left[1\dots 9\right]$. For a given signal, compute the centre point (c) with an adjacent point. For each sample point, calculate the gradient value as $x\left[i\right]=\left|x\left[i\right]-c\right|$ for $i=0,1,2,\dots ,n$. Compare the gradient values, if $x\left[i\right] \ge c$, when the value of 1 is set, if not 0 will be assigned. Obtained binary code is converted into decimal representation.