Comparison of error detectors for time delay tracking

This paper discusses algorithm and design tradeoffs for time-delay trackers based on a generalized tracker model which includes both open loop and closed loop configurations. The discussion focuses on the error detector function which relates the tracking problem to optimum time-delay estimation. Two examples of open loop trackers are presented along with a discussion of considerations for selecting between open loop and closed loop methods. Four measures of (closed loop) error detector performance are presented which reflect acquisition, dynamic following capability, and sensitivity to interference in addition to optimality of tracker variance.