Femtosecond frequency comb is a great invention in the field of metrology at the end of the last century. It can simply and effectively synchronize the phases for optical signals of different wavelengths or RF signals. Erbium doped fiber optical comb has many advantages. The National Time Service Center of Chinese Academy of Sciences has launched a project on the new type erbium-doped fiber femtosecond optical comb research. This paper introduces the signal source which is designed for this project. DDS chip AD9854 is used as the signal source. The signal source output has a wideband from 1–80 MHz. Test result for the signal source is discussed.