Technical Article

Quantitative Analysis of Break-lock in Monopulse Receiver Phase-locked Loop Using Noise Jamming Signal

It is evident that noise jamming is one of the several active jamming techniques employed against tracking radars and missile seekers. The noise jamming mainly aims at completely masking the desired radar signal by the externally injected noise signal. Of several parameters to be considered for the analysis of noise jamming problem, the noise jammer power is one of the most critical parameter. In this paper, emphasis is given for estimation and quantitative analyses of the effectiveness of break-lock in a missile borne phase locked loop (PLL) based monopulse radar receiver using external noise signal.

The analyses involve estimating the jamming signal power required to break-lock as a function of radar echo signal power through computer simulation and experimental measurements. The simulation plots representing the receiver PLL output are presented for selected echo signal powers from -14 dBm to -2 dBm. The simulation results are compared and verified with experimental results and it is established that these results are close approximate within 2 dB. It is noted that the measured values of jamming signal power at break-lock using HMC702LP6CE, HMC703LP4E and HMC830LP6GE PLL synthesizers are -19.5 dBm, -18.1 dBm and -17.6 dBm, respectively, while the simulated value is -18.8 dBm for a typical radar echo signal power of -10 dBm. The fairly good and consistent agreement between these results validates the simulation data.

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