# US 2014/0064347 A1 · Systems and methods for carrier phase recovery > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0064347 A1 - Document ID: US20140064347A1 - Status: Published application - Kind: A1 - Application number: 13/599,806 - Filed: 2012-08-30 - Published: 2014-03-06 - Earliest claimed: 2012-08-30 - Assignees: The Boeing Company - Inventors: Leonard Alan Plotke; Ramin Nobakht - Web page: https://patentgrep.com/patent/US20140064347A1 ## CPC - H04B 17/336: Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] - H04L 27/0014: {Carrier regulation (of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657)} - H04L 2027/0067: {Phase error detectors} - H04L 2027/0069: {Loop filters} - H04L 2027/0081: {between loops of different bandwidths} - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Systems and methods for carrier phase recovery are provided. One method includes providing a reference signal, detecting an input signal and determining a Signal to Noise Ratio (SNR) of the input signal. The method also includes employing a Minimum Mean Square Error (MMSE) algorithm based on the SNR to determine a Carrier Phase Recovery Loop (CPRL) bandwidth. ## Claims ### Claim 1 A method to determine a Carrier Phase Recovery Loop (CPRL) bandwidth, the method comprising: providing a reference signal; detecting an input signal; determining a Signal to Noise Ratio (SNR) of the input signal; and employing a Minimum Mean Square Error (MMSE) algorithm based on the SNR to determine a CPRL bandwidth. ### Claim 2 (depends on 1) The method of claim 1, wherein the MMSE employed is based on a predetermined SNR threshold value. ### Claim 3 (depends on 1) The method of claim 1, wherein the MMSE algorithm calculates a difference between a phase error of the reference signal and a phase error of the detected input signal. ### Claim 4 (depends on 1) The method of claim 1, wherein the MMSE algorithm uses a combined mean-squared error signal to determine an MMSE. ### Claim 5 (depends on 1) The method of claim 1, wherein the MMSE algorithm uses a mean-squared error signal of the reference signal and the input signal to determine an MMSE. ### Claim 6 (depends on 1) The method of claim 1, wherein if the SNR is less than a predetermined value, the MMSE algorithm calculates a difference in mean-squared errors of a reference signal phase error and a mean-squared error of at least one detected signal phase error. ### Claim 7 (depends on 1) The method of claim 1, wherein if the SNR is greater than a predetermined value, the MMSE algorithm calculates a difference in mean-squared errors of a reference signal phase error and a mean-squared error of at least one detected signal phase error. ### Claim 8 (depends on 1) The method of claim 1, further comprising optimizing the CPRL bandwidth for a plurality of waveforms. ### Claim 9 (depends on 1) The method of claim 1, wherein the MMSE algorithm determines a minimum of a mean-squared error of a combined signal over a plurality of values for a product of the CPRL bandwidth and a symbol time if the SNR of the input signal is less than a predetermined value. ### Claim 10 (depends on 1) The method of claim 1, wherein the MMSE algorithm determines a minimum of a mean-squared error of a combined signal over a plurality of values for a product of the CPRL bandwidth and a symbol time if the SNR of the input signal is greater than a predetermined value. ### Claim 11 (depends on 1) The method of claim 1, wherein the MMSE algorithm determines a difference between a mean-squared error of the input signal and a minimum of a mean-squared error of the reference signal over a plurality of values for a product of the CPRL bandwidth and a symbol time if the SNR of the input signal is greater than a predetermined value. ### Claim 12 (depends on 1) The method of claim 1, wherein the MMSE algorithm determines a difference between a mean-squared error of the input signal and a mean-squared error of the reference signal over a plurality of values for a product of the CPRL bandwidth and a symbol time if the SNR of the input signal is greater than a predetermined value. ### Claim 13 (depends on 1) The method of claim 1, wherein the MMSE algorithm determines a minimum of a mean-squared error of the input signal over a plurality of values for a product of the CPRL bandwidth and a symbol time if the SNR of the input signal is greater than a predetermined value. ### Claim 14 A demodulator comprising: an adaptive Carrier Phase Recovery Loop (CPRL) having, a Phase-Locked Loop (PLL) configured to detect an input signal; and a Minimum Mean Square Error (MMSE) module configured to receive as an input phase error vectors based on a phase component of a reference signal and a phase component of the input signal, the phase error vectors defining a mean-squared error, the MMSE module further configured to determine a CPRL bandwidth using the mean-squared error. ### Claim 15 (depends on 14) The demodulator of claim 14, wherein the MMSE module is configured to determine an MMSE algorithm to use based on a predetermined SNR threshold value. ### Claim 16 (depends on 15) The demodulator of claim 15, wherein the MMSE module determines a minimum of a mean-squared error of a combined signal over a plurality of values for a product of the CPRL bandwidth and a symbol time if the SNR of the input signal is less than a predetermined value. ### Claim 17 (depends on 15) The demodulator of claim 15, wherein the MMSE module determines a minimum of a mean-squared error of a combined signal over a plurality of values for a product of the CPRL bandwidth and a symbol time if the SNR of the input signal is greater than a predetermined value. ### Claim 18 (depends on 15) The demodulator of claim 15, wherein the MMSE module determines a difference between a mean-squared error of the input signal and a minimum of a mean-squared error of the reference signal over a plurality of values for a product of the CPRL bandwidth and a symbol time if the SNR of the input signal is greater than a predetermined value. ### Claim 19 (depends on 15) The demodulator of claim 15, wherein the MMSE module determines a difference between a mean-squared error of the input signal and a mean-squared error of the reference signal over a plurality of values for a product of the CPRL bandwidth and a symbol time if the SNR of the input signal is greater than a predetermined value. ### Claim 20 (depends on 15) The demodulator of claim 15, wherein the MMSE module determines a minimum of a mean-squared error of the reference signal over a plurality of values for a product of the CPRL bandwidth and a symbol time if the SNR of the input signal is greater than a predetermined value. ### Claim 21 A communication system comprising: a transmitter configured to transmit a modulated signal; a receiver configured to receive the modulated signal; and a demodulator configured to demodulate the received modulated signal, the demodulator including, an adaptive Carrier Phase Recovery Loop (CPRL) having, a Phase-Locked Loop (PLL) configured to detect an input signal; and a Minimum Mean Square Error (MMSE) module configured to receive as an input phase error vectors based on a phase component of a reference signal and a phase component of the input signal, the phase error vectors defining a mean-squared error, the MMSE module further configured to determine a CPRL bandwidth using the mean-squared error.