Estimation of break-lock in PLL synthesizers for monopulse radar applications: Experimental and simulation approach

This work presents and estimates the break-lock in phase locked loop (PLL) synthesizers for monopulse radar applications through experimental measurements and computer simulation. Sinusoidal continuous wave (CW) and linear frequency modulated (LFM) signals are used as repeater jamming signals. The CW jamming signal power as a function of radar echo signal power at break-lock is estimated for different values of frequency difference between these two signals, and from these results the jammer to echo signal power (J/S) ratio (in dB) is computed. Break-lock is achieved at a J/S ratio of 1.9 dB (measured at 1.8 dB) for a typical echo signal power of −5 dBm with a 1 MHz frequency difference. The frequency deviation as a function of J/S ratio required to break-lock is estimated for different modulation rates in the presence of LFM jamming signal. Break-lock is achieved at a frequency deviation of 0.34 MHz (measured at 0.32 MHz) for a J/S ratio of 2 dB and 200 kHz modulation rate. The simulation models are proposed accordingly to the data obtained from the experimental setups. Good and consistent agreements between the measured and simulated results are observed and can be useful in the design of CW and LFM jammers in the target platform.