Definition - What does Synchronous Transmission mean?
Synchronous transmission is a data transfer method which is characterized by a continuous stream of data in the form of signals which are accompanied by regular timing signals which are generated by some external clocking mechanism meant to ensure that both the sender and receiver are synchronized with each other.
Data are sent as frames or packets in fixed intervals.
Techopedia explains Synchronous Transmission
Synchronous transmission is transmission of signals in a fixed interval based on a predefined clocking signal and is meant for constant and reliable transmission of time-sensitive data such as VoIP and audio/video streaming.
This method of transmission is used when large amounts of data need to be transferred quickly since data is transferred in large blocks instead of individual characters. The data blocks are spaced and grouped in regular intervals and preceded by synchronous characters that a remote device decode and use to synchronize the connection between the end points.
After synchronization is complete, the transmission can begin.