Several modulation techniques are defined in digital modulation, Here we are discussing about in four modulation techniques,8-PSK,8-TAPSK,16TAPSK and 16-QAM. In the paper we derive minimum non coherent distance(dnc)of block coded TAPSK and compare it with different modulation techniques, i.e. 8-PSK and 16-QAM using linear component codes. If the block length N is very small.NBC-16-TAPSK perform...