An apparatus and method are disclosed for testing synchronization of transmission between systems operating at different clock rates. The apparatus includes a transmitting unit configured to operate at a first clock rate, and a receiving unit configured to operate at a second clock rate that is different from the first clock rate. A compensation circuit receives a second clock rate from a frequency generating system, and synchronizes the data transmitted by the transmitting unit with the second clock rate. The synchronized data is then transmitted to the receiving unit.