Delay length locked loop in target range tracking

A delay length locked loop (DLL) synthesized with a stack of parallel shift registers which would adjust automatically its delay length based on the delayed time difference between the analog input signal and the reference signal is employed for selected applications in sonars and radar. Target range tracking is one application wherein the target being tracked is locked to the DLL and the target range in terms of its delay period is continuously monitored by the system. A re-circulated digital delay line (RDDL) constructed using the DLL offers integration improvement in pulse radar and sonar systems. Another application of the RDDL in passive sonar identification is also reported