生成PN序列（伪随机噪声序列），阶数包括2阶，3阶，4阶，5阶，6阶，7阶，8阶。并在前面补0后形成相应的2的幂次长的序列。-Generated PN sequences (pseudo-random noise sequence), including the orders of 2 order, 3 order, 4 order, 5 order, 6 order, 7 order, 8 order. And fill in fro