A.GPS系統(tǒng) B.北斗系統(tǒng) C.格洛納斯系統(tǒng) D.伽利略系統(tǒng)
A.簡(jiǎn)單網(wǎng)絡(luò)時(shí)間協(xié)議(SNTP) B.IRIG-B C.1PPS D.1PPM
A.99.90% B.99.60% C.99.50% D.99.00%