Broadcast/non-broadcast MUSE signal sound decoder with a variable protection period

摘要

A MUSE sound decoder detects a broadcasting/non-broadcasting identification flag included in the control signals in an applied MUSE signal to determine whether the MUSE signal is broadcasted or non-broadcasted. The MUSE sound decoder further includes a frame synchronization protection circuit for protecting frame synchronization over a predetermined frame synchronization protection time period when the frame synchronization pattern is not detected at the proper timing. The frame synchronization protection circuit sets the frame synchronization protection time period to a long time period when the MUSE signal is determined to be a broadcasted MUSE signal, and to a short time period when the MUSE signal is determined to be a non-broadcasted MUSE signal. Appropriate muting of a sound signal can be carried out according to the condition of the received MUSE signal.