Modified delay-locked loop for fading channels

The delay-locked loop (DLL) is well suited to guarantee fine synchronization for direct-sequence spread spectrum systems. In fading channels the mean time to lose lock (MTLL) of a DLL is very important because a loss of loci during a fade makes a re-acquisition process necessary. Using a two state model for the fading channel and a modified DLL will improve the MTLL considerably. The modified DLL operates in two different modes: a normal tracking mode for good channel conditions, and a “fade” mode for bad channel conditions, i.e. during a deep fade. The modified DLL is more robust against bad channel conditions