PURPOSE: To simplify and economize a continuity test circuit and to reduce the test processing, by providing a folding link to a specific terminal of a 4-wire network, and returning a continuity test signal.
CONSTITUTION: The continuity test of the channel between stations of the common line system where the channel is constituted with four wires is conducted. An outgoing station of a preceding station closes a network 10 to connect an outgoing continuity test trunk (OCT)13 to A.B lines of a channel line 40 and an incoming continuity test trunk(TCT)14 to D.E lines, and a continuity test signal is transmitted between the lines A.B from the OCT13. On the other hand, an incoming station of a succeeding station is provided with a reflexing link 34 connecting the lines A and D and the lines B and C to a set terminal 33, and the channel line 40 and the specific terminal 33 are connected by closing the network 30. The continuity test signal transmitted from the preceding station is returned to the preceding station via the reflexing link 34 and detected at the TCT14. Thus, the propriety of the continuity test is discriminated.
AIBA TATSUO
HASHIMOTO MASASHI
ISHIKAWA KIYOKAZU
TOKUNAGA YUUJI
NIPPON TELEGRAPH & TELEPHONE
HITACHI LTD
OKI ELECTRIC IND CO LTD
FUJITSU LTD