Patent ID: 7477707
Filing Date: 2009-01-13
Classification: H04L

Abstract:
1. A differential phase shift keying (DPSK) receiver to receive a DPSK input signal transmitted by a DPSK transmitter, comprising: means for converting the input signal to in-phase and quadrature components; a differential demodulator to determine a demodulated phase by comparing the in-phase and quadrature components of the input signal with a first delayed, conjugated version of the in-phase and quadrature components of the input signal; a frequency offset calculation circuit to determine a frequency offset between an oscillator in the DPSK receiver and an oscillator in the DPSK transmitter by comparing the in-phase and quadrature components of the input signal with a second delayed, conjugated version of the in-phase and quadrature components of the input signal, wherein the delay associated with the second delayed, conjugated version of the in-phase and quadrature components of the input signal is approximately one sample interval, and wherein the approximately one sample interval is less than one symbol interval; a frequency correction circuit to correct the demodulated phase using the frequency offset into a corrected phase; a phase correction circuit to determine an absolute phase using the corrected phase; and a symbol mapping circuit to map the absolute phase to an output symbol, comprising one or more bits of data.