| 摘要 |
PURPOSE:To exchange the connection between optional terminals each other by converting a signal having frequency sent from a terminal into the frequency of its opposite terminal in a system assigning inherent frequency to each terminal. CONSTITUTION:An exchange 2 selects four waves fi-fl e.g. out of many signal frequency fx inputted from a transmission line 3 by a selection part 5 on the basis of a command of a controller 6. Then, the frequency fi is led into a frequency switch 4 and a local oscillator 8 is driven by the difference of frequency DELTAf between an objective frequency ft and the input frequency fl on the basis of the command from the controller 6 and both the frequency are mixed by a mixer 7. The obtained objective frequency ft is collected from frequency switches 4 and then sent to the transmission line 3 again. The previously fixed frequency in the signal on the transmission line 3 is received only by the terminal 1 of ft. Consequently, a channel between the terminal 1 having the frequency fi and the terminal 1 having frequency ft is formed. |
