earticle

영어

In this paper, the break-lock phenomenon of phase locked loop (PLL) in monopulse radar receiver for missile seeking applications is presented. The continuous wave radar echo and linear frequency modulated (LFM) interference signals are injected into the PLL simultaneously with an assumption that initially, the PLL locks on to the echo signal frequency. The PLL is assumed to be operating at an intermediate frequency (IF) of 50 MHz with a typical bandwidth of 200 kHz. The frequency deviation required to break-lock as a function of interference signal power and modulation rate is analyzed. The simulation results show that break-lock is achieved at a frequency deviation of 0.36 MHz for a typical LFM signal power of -14 dBm and 200 kHz modulation rate. The break-lock in the PLL is also estimated for selected values of LFM signal power and modulation rates, such as 300, 400 kHz, when the echo signal power at the PLL input is -10 and -14 dBm. The PLL with third order passive loop filter is modeled and designed using exact method. The computer simulation is carried out using visual system simulator (VSS) AWR software and potential conclusions are demonstrated.