Radio Doppler racking system for rocket usually only use one carrier frequency. This paper discusses a method of radio Doppler for tracking rocket using two-frequency radio waves. The system uses Doppler frequency transponder on 465 MHz and 2400 MHz simultaneously. Low frequency radio used to measure high-speed rocket and conversely higher frequency radio waves are used to measure the low-speed rocket. Results obtained using this method are 5.4 times more accurate at speeds less than Mach 0.7 compared with the results of the Doppler system that uses only one radio frequency. This method is suitable for measuring rocket speed up to Mach 3.8.
Keywords: Doppler tracking, Rockets, Two-frequency, High-resolution, Transponder