Performance of a tracking status detector for a digital delay lock loop
Abstract
A lock detector for providing precise time synchronization in a satelliteearth communication system is proposed and analyzed. The detector is operated on the principal that the instantaneous phase error determines the loop tracking status. The proposed detector is analyzed by a Markov random walk model. Two sets of probabilities were determined: the probability of detecting the outoflock condition given that the loop was out of lock, and the probability of exceeding the threshold given that the loop was in lock. It was found that at a signaltonoise ratio of 6 dB, a 0.9999 probability of outoflock detection is attainable. The probability of one or more false alarms in one year was less than 1/100,000. The frequency drift estimator is also discussed.
 Publication:

International InstrumentationAutomation Conference
 Pub Date:
 1974
 Bibcode:
 1974isa..conf..276H
 Keywords:

 Phase Error;
 Phase Locked Systems;
 Telecommunication;
 Time Lag;
 Tracking Filters;
 Boundary Value Problems;
 Communication Satellites;
 Digital Systems;
 Error Signals;
 Feedback Control;
 Low Pass Filters;
 Markov Processes;
 Mathematical Models;
 Signal To Noise Ratios;
 Tracking Radar;
 Space Communications, Spacecraft Communications, Command and Tracking