Doppler detection by an improved PLL technique

Phase-lock-loops can be modified to detect Doppler frequency even for short radar pulse duration and low Doppler frequency. It is shown both theoretically and experimentally that the PLL (phase locked loop) technique can be improved to do so, by giving an artificial difference between input frequency and voltage-controlled oscillator free running frequency. This technique has an application in low-level signal-to-noise ratio operation, as in antiradiation missile detection