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comm.PSKCarrierPhaseSynchronizer System object

Package: comm

Recover carrier phase of baseband PSK signal

Description

The PSKCarrierPhaseSynchronizer object recovers the carrier phase of the input signal using the M-Power method. This feedforward method is not data aided but is clock aided. You can use this method for systems that use baseband phase shift keying (PSK) modulation. The method is also suitable for systems that use baseband quadrature amplitude modulation (QAM). However, the results are less accurate than those for comparable PSK systems. The alphabet size for the modulation requires an even integer.

To recover the carrier phase of the input signal using the M-Power method:

  1. Define and set up your PSK carrier phase synchronizer object. See Construction.

  2. Call step to recover the carrier phase of the input signal according to the properties of comm.PSKCarrierPhaseSynchronizer. The behavior of step is specific to each object in the toolbox.

Construction

H = comm.PSKCarrierPhaseSynchronizer creates a PSK carrier phase synchronizer System object™, H. This object recovers the carrier phase of a baseband phase shift keying (PSK) modulated signal using the M-power method.

H = comm.PSKCarrierPhaseSynchronizer(Name,Value) creates a PSK carrier phase synchronizer object, H, with each specified property set to the specified value. You can specify additional name-value pair arguments in any order as (Name1,Value1,...,NameN,ValueN).

H = comm.PSKCarrierPhaseSynchronizer(M,Name,Value) creates a PSK carrier phase synchronizer object, H. This object has the ModulationOrder property set to M, and the other specified properties set to the specified values.

Properties

ModulationOrder

Number of points in signal constellation

Specify the modulation order of the input signal as an even, positive, real scalar value. Choose a data type of single or double. The default is 2. This property is tunable.

ObservationInterval

Number of symbols where carrier phase assumed constant

Specify the observation interval as a real positive scalar integer value. Choose a data type of single or double. The default is 100.

Methods

cloneCreate PSK carrier phase synchronizer object with same property values
getNumInputsNumber of expected inputs to step method
getNumOutputsNumber of outputs from step method
isLockedLocked status for input attributes and nontunable properties
releaseAllow property value and input characteristics changes
resetReset states of the PSK carrier phase synchronizer object
stepRecover baseband PSK signal's carrier phase

Examples

Recover carrier phase of a 16-PSK signal using M-power method.

M = 16;
phOffset = 10 *pi/180;  % in radians
numSamples = 100;
% Create PSK modulator System object
    hMod = comm.PSKModulator(M, phOffset, 'BitInput',false);
% Create PSK carrier phase synchronizer System object
    hSync = comm.PSKCarrierPhaseSynchronizer(M,...
                        'ObservationInterval',numSamples);
% Generate random data
    data = randi([0 M-1],numSamples,1);
% Modulate random data and add carrier phase
    modData = step(hMod, data);
% Recover the carrier phase
    [recSig phEst] = step(hSync, modData);
fprintf('The carrier phase is estimated to be %g degrees.\n', phEst);

Algorithms

This object implements the algorithm, inputs, and outputs described on the M-PSK Phase Recovery block reference page. The object properties correspond to the block parameters.

See Also

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