Digital tanlock loop with extended locking range using variable time delay

In this work, the locking range and frequency acquisition characteristics of the time delay digital tanlock loop (TDTL) have been enhanced by adjusting the loop gain and the system time delay. These parameters are automatically controlled by a finite state machine. Through this adaptive process, the system can robustly overcome any frequency disturbances that may cause the loop to go out of lock. Simulation results of the new structure show that the newly developed loop can offer rapid acquisition and good tracking performance over a wide locking range. These new enhancements will allow the loop to be used in a wide range of signal processing applications.