Frequency lock loops research of rendezvous and docking radar system

The performance of frequency lock loops (FLL) is researched. In order to reduce the frequency lock loops discriminate error and convergence time, a bandwidth-switching method is proposed. First FLL is designed with wide bandwidth for large dynamic environment, after the loop error decreases, reset the filter registers. And then the bandwidth is reduced to improve the discriminate precision. The simulation analyses show that the bandwidth-switching method can effectively reduce discriminate error and solve the contradiction of thermal noise error and dynamic error.