Loop line type calling system

Abstract

Abstract PURPOSE:To attain simultaneous calling among >=2 persons in a loop-constituted line by inserting one adding circuit and one subtracting circuit into a loop. CONSTITUTION:A transmission signal 5 from a sound terminal 2 is stored in a storage circuit 6 storing calling signal 5 from voice terminal 2 only by a time part to be equal to one turning loop delay time, and on the other hand, the output signal of the storage circuit 6 is subtracted from the voice sum input signal 4 of a channel (i) in a transmission line 1, in which the voice sum signal is transmitted, by a subtracting circuit 7. As a result, the voice sum signal excepting for a self-transmission signal can be obtained for the output of the subtracting circuit 7. Next, the new self-transmission signal is added to the output signal of the subtracting circuit 7 by an adding circuit 8 and transmitted through the loop type transmission line 1 to the node equipment 3 of a next step as a voice sum output signal 9. When a voice excepting for the self-transmission signal can be received and listened, a self-receiving signal 10 goes to the sum signal of all transmission signals from the other voice terminals. Thus, the simultaneous call among the plural persons can be executed in the loop line.

Inventors

• 👤 Masaharu Shimada
• 👤 正治 島田

Bibliographic Details