The article investigates the possibilities of closed and combined synchronization systems for operation in the conditions of phase instability of generators caused by the influence of ionizing radiation of outer space. The inconsistency of the closed-type synchronization system with respect to minimizing the variance of phase errors and increasing the dynamics during carrier frequency tracking is shown. For the combined synchronization system, the article clarifies the process of open communication synthesis and proposes analytical dependences that allow the technique of open communication synthesis to be specified taking into account the phase instability of generators caused by the ionizing radiation of space.