| 摘要 |
<p>The switching unit comprises for two-way transmission two branches, each of which includes in series an input mixer, a channel filter and an output mixer, and two variable frequency digitally controlled carrier current generators the first of which feeds the input mixer of the first branch and the output mixer of the second branch, and the other of which feeds the output mixer of the first branch and the input mixer of the second branch. In a switching arrangement using such units, a telephone channel can be transferred from an incoming multiplexed group to an outgoing multiplexed group without any low-frequency stages by means of two units whose second generators receive a common frequency, while their first generators respectively receive frequencies corresponding to the positions of the considered channel in the incoming and outgoing groups respectively.</p> |
