Patent ID: 8711035

Claim:
An apparatus comprising: a phase rotator configured to receive a correlated in-phase signal, a correlated quadrature-phase signal, and a selected roll phase estimate as inputs and to generate a rotated correlated in-phase signal and a rotated correlated quadrature-phase signal by rotating the correlated in-phase signal and the correlated quadrature-phase signal, respectively, in response to the selected roll phase estimate; a frequency-locked loop (FLL) acquisition loop configured to receive the correlated in-phase signal and the correlated quadrature-phase signal as inputs, to frequency lock to the correlated in-phase signal and the correlated quadrature-phase signal, and to generate a roll rate error and an FLL roll phase as outputs; a phase-locked loop (PLL) tracking loop configured to receive the correlated in-phase signal and the correlated quadrature-phase signal as inputs, to track an amplitude modulation of the correlated in-phase signal and the correlated quadrature-phase signal, and to generate an indication of a phase of the amplitude modulation of the correlated in-phase signal and the correlated quadrature-phase signal as an output; an FLL lock detector configured to receive the roll rate error as an input and to generate an FLL/PLL mode control based at least partly on whether or not the roll rate error is within a pull-in range of the PLL tracking loop; and a mode selector configured to receive the FLL roll phase, the PLL roll phase, and the FLL/PLL mode control as inputs, and to select one of the FLL roll phase or the PLL roll phase as a selected roll phase estimate output based on a state of the FLL/PLL mode control such that the phase rotator and the FLL acquisition loop are configured to frequency lock to the amplitude modulation of the correlated in-phase signal and the correlated quadrature-phase signal when the mode selector is in an FLL mode and such that the phase rotator and the PLL tracking loop are configured to phase lock to the amplitude modulation of the correlated in-phase signal and the correlated quadrature-phase signal when the mode selector is in a PLL mode.