Application of IC Implemented Phase-Locked Loop System to Recover Information from Noise

Abstract

This paper describes the design and operation of a practical IC implemented phase-locked loop system capable of indicating phase changes in a noisy slowly varying DC signal of period, T = 18 sec., by providing a logic compatible square or triangular wave output which is locked in phase with the input signal. The results of tests indicate that the practical PLL system performed satisfactorily under normal operating conditions. The extremely low average phase error of +5 degrees between the noisy input and the PLL output signals, which is well within the desired limit of +/- 10 degrees, indicates the high degree of accuracy made possible with the use of the highly stable IC implemented PLL design. This shows that a practical IC implemented phase-locked loop can be designed and used to accurately track and clean up a low frequency noisying input signal to recover information from noise.