发明名称 TEST SWITCHING CIRCUIT
摘要 PURPOSE:To attenuate a leakage signal from a test signal generator and to prevent the deterioration of a signal to noise ratio in a transmission signal while a test is not conducted by using two test switches for test signal insertion by cascade-connecting them in two stages. CONSTITUTION:A hybrid 1 branches the transmission signal of data and the like into two, and inputs one transmission signal to a standby transmission device and the other to a present line transmission device through a test switch 3. A test signal outputted from the test signal generator 2 is inputted from the output side 7 of a test switch 4 to the input side 8 of the switch 3 while the test is conducted. While the test is not conducted, the test signal is terminated in the terminator 6 of the switch 4 and the isolation of the leakage signal to the output side 7 is secured. Furthermore, the leakage signal is terminated in the terminator 5 of the switch 3, and isolation with respect to the direction of a present line is secured. Thus, noise for the transmission signal is reduced.
申请公布号 JPH01305735(A) 申请公布日期 1989.12.11
申请号 JP19880137737 申请日期 1988.06.03
申请人 NEC CORP 发明人 HANEDA SADAYOSHI
分类号 H04B1/74;H04B17/00 主分类号 H04B1/74
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