PAM-Based Timing Synchronization for ARTM Modulations

Abstract

A reduced-complexity decision-directed timing recovery method for continuous phase modulation (CPM) is presented. The timing recovery method is based on the pulse amplitude modulation (PAM) representation - or Laurent representation - of CPM, and is applied to the family of three telemetry modulations: PCM/FM, SOQPSKTG, and ARTM CPM. This work is the next step in an ongoing effort to develop reduced-complexity PAM-based receiver methods for aeronautical telemetry. We quantify the steady-state tracking accuracy of the proposed timing recovery method and show that it performs very close to the theoretical limit given by the modified Cramer-Rao bound (MCRB).We also demonstrate that the proposed method is free of false-lock points for all three modulations.