The iniG704-E1 framer core is designed to handle synchronous frame structures (Recommondation G.704) running on E1 carrier. Transmit and receive part are designed as individual blocks, both independently handle basic and multi frames. Both blocks perform functions such as overhead bit insertion / detection, CRC4 computation and check. The synchronization unit synchronizes automatically or by means of an external frame sync signal. The frame builder can be ci=onfigured which of the overhead bits are to be inserted or not.