Patent ID: 8488697

Claim:
A timing recovery system that provides a timing estimate between a transmitter clock and a receiver clock, said system comprising: a first direct down-converter receiving in-phase and quadrature phase signals and down-converting the in-phase and quadrature phase signals to first down-converted in-phase and quadrature phase baseband signals; a second direct down-converter receiving in-phase and quadrature phase signals and down-converting the in-phase and quadrature phase signals to second in-phase and quadrature phase baseband signals, where the first in-phase and quadrature phase baseband signals and the second in-phase and quadrature phase baseband signals are 90° apart in phase; a first filter for filtering the first in-phase and quadrature phase baseband signals to remove zero terms; a second filter for filtering the second in-phase and quadrature phase baseband signals to remove zero terms; a square-law non-linearity circuit that receives the filtered first in-phase and quadrature phase baseband signals and the filtered second in-phase and quadrature phase baseband signals and providing squaring non-linearity between the first and second baseband signals to generate non-linear in-phase and quadrature phase signals, wherein the square-law non-linearity circuit squares the first in-phase baseband signal, squares the first quadrature phase baseband signal, squares the second in-phase baseband signal and squares the second quadrature phase baseband signal, said square-law non-linearity circuit further adding the squared signals to generate the non-linear in-phase signal, and wherein the square-law non-linearity circuit multiplies the first and second in-phase baseband signals and multiplies the first and second quadrature phase baseband signals, and then adds the multiplied signals to generate the non-linear quadrature phase signal; and a post-filter circuit receiving the non-linear in-phase and quadrature phase signals and producing the timing estimate.