An Intelligent Digital Phase-Locked Loop with Integral Gain Control, Signal Quality and Lock Detection

Abstract

An intelligent digital phase-locked loop with integral automatic gain control, signal quality and lock detection suitable for implementation using current digital signal processing devices is presented. By exploiting information derived from these functions operating in unison, it is possible to realize improved performance in an adverse environment where fading or abrupt signal outages are encountered. The system described consists of several functions operating under the direction of a stored program. The state diagram model of the program is discussed along with design considerations for the system elements. Various aspects of the system are simulated in the presence of noise and signal outage and compared to the performance of a conventional phase-locked loop.