  Precise calibration of the cavity phase signals is necessary for the
operation of any particle accelerator. For many systems this requires human in
the loop adjustments based on measurements of the beam parameters downstream.
Some recent work has developed a scheme for the calibration of the cavity phase
using beam measurements and beam-loading however this scheme is still a
multi-step process that requires heavy automation or human in the loop. In this
paper we analyze a new scheme that uses only RF signals reacting to
beam-loading to calculate the phase of the beam relative to the cavity. This
technique could be used in slow control loops to provide real-time adjustment
of the cavity phase calibration without human intervention thereby increasing
the stability and reliability of the accelerator.
