Remote bistatic receiver synchronization using DLL techniques

Abstract

Pulse to pulse staggering in the pulse reference interval (PRI), usually used to increase the radar unambiguous range and MTI blind speeds, complicates notably the synchronization of the pulsed waveform. A free running open loop technique may be used for this purpose, adjusting a stable clock at the same frequency as the transmitted pulses, which is synchronized by the received sequence during direct illumination. When the received signal can be contaminated by interferences, noise, or multipath effects, a more robust closed loop approach is desirable. This paper presents a closed loop solution to the synchronism process, based on a delay-lock loop configuration, using the special properties of the pulse to pulse staggered signal, that can be considered as a digital pseudorandom code modulation with a period equal to the PRI