This paper introduces the two methods of long range and high precision time-frequency trace to source and compare about Satellite two way and satellite co-vision, directed towards the practical difficulties faced by the measurement and calibration of core equipment of Loran C transmitter time-frequency system, based on these methods, an on-line measurement and calibration method for time-frequency system of the Loran C transmitter is proposed, The feasibility of this method is verified by test.