| 摘要 |
PURPOSE:To prevent the speech unavailability caused by a pseudo- synchronization of CODECs for executing encoding and decoding with high efficiency by constituting the system so that only a frame synchronization pattern can be sent out in the case of a state that the frame synchronization is not taken, even if two CODECs are connected through a transmission network. CONSTITUTION:When CODECs 1, 2 are connected through a transmission network 5 containing an exchange, etc., frame synchronizing pull-in by synchronizing circuits 3, 4 is started, and also, high efficiency encoding is stopped by masking a sound signal by mask parts 6, 7, and when a synchronization establishment notice is received, the mask by the mask parts 6, 7 is released, and high efficiency encoding is started. Accordingly, frame synchronizing pull-in by only a frame synchronization pattern is executed, a pseudo-synchronization is prevented. In such a way, the speech unavailability caused by the pseudo- synchronization of the CODECs 1, 2 for executing encoding and decoding with high efficiency can be prevented. |
