| 摘要 |
PURPOSE:To prevent an error mute of a voice in the course of a call, by operating a detector of a word synchronizing signal for showing a head position of each word in a data, only when a bit synchronizing signal is being detected, and operating the word synchronizing signal detector only when the data is being sent. CONSTITUTION:A monostable multivibrator (OSM) 21 and an AND gate 22 are added newly. The OSM 21 is triggered by an output 12 of a bit synchronization detecting circuit, and its pulse width is set so as to be held until a word synchronizing signal which follows a bit synchronizing signal is ended. The AND gate 22 gives a reference clock 15 of a data to a frame synchronization detecting circuit 7 only while an output 23 of the OSM is 'H'. An input to the word synchronization detecting circuit 7 is given only when the bit synchronization detecting circuit 2 is ON. As a result, an output of the word synchronization detecting circuit 7 is not generated except the time of receiving a data, therefore, it is prevented that a voice an a noise are judged to be a data by mistake. |
