A.DIRTLX+OPR+BRK+ B.DIRTLZ+KKKK+BRK+ C.DIRLTX+KKKK+GA+ D.TLX+KKKK+BRK+
A.KKKK+ B.BRK+ C.OVER+ D.NNNN
A.呼叫对象 B.呼叫者识别 C.自检 D.自己检测对方信号的质量