| 摘要 |
PURPOSE:To make plural conference services due to an optional nmber of subscriber's telehone sets, by providing a circuit, which consists of an adding circuit and a subtracting circuit and achieves a conference service, and a memory where the channel on the boundary between conference services is stored. CONSTITUTION:Memories 1 and 2 store signal data of time division channels for every frame, and a memory 7 stores the use state of channels and a channel on the boundary for another conference service corresponding to memories 1 and 2. An adding circuit 3 adds the value of the output of the memory 1 and the value of a temporary storage register 4 and stores the addition result into the temporary storage register 4 again. In case that data indicating the boundary between conference services is read out from the memory 7, the value of the register 4 is transferred to a FIFO circuit 5, and addition is performed newly. A subtracting circuit 6 subtracts the output value of each channel of the memory 1 from the value of the FIFO circuit 5 and transfers the subtraction result to the memory. |
