Hello all,
I am currently at the example "symbol_differential_filter.grc" in the GNU Radio tutorial. It's in the chapter "QPSK Mod and Demod". My question is how taps [-1, 0, 1] is implementing the differentiation in "Decimating FIR Filter" block.
For first difference, the equation should be y[n] = x[n] - x[n-1]. In that case the taps should be [1, -1]. Here is my confusion. Why taps [-1, 0, 1] have been used and which difference it is implementing?
Regards,
Shuvodip