THE INFLUENCE OF ARM FILTER DELAY ON TRACKING PERFORMANCE OF A COSTAS LOOP

Abstract

It is demonstrated that the effect of the arm filters with NRZ data in a second-order Costas loop is to introduce delay in the loop which causes the tracking-error jitter to increase. It is shown that the tracking-error jitter becomes unbounded at exactly the same value of delay as the loop becomes unstable. The results are derived for both the one pole passive and the Integrate and Dump arm filter cases. A representative calculation shows that this is normally not a significant problem in properly designed loops.