Contents

comm.DBPSKDemodulator System object

Package: comm

Demodulate using DBPSK method

Description

The DBPSKDemodulator object demodulates a signal that was modulated using the differential binary phase shift keying method. The input is a baseband representation of the modulated signal.

To demodulate a signal that was modulated using differential binary phase shift keying:

  1. Define and set up your DBPSK demodulator object. See Construction.

  2. Call step to demodulate a signal according to the properties of comm.DBPSKDemodulator. The behavior of step is specific to each object in the toolbox.

Construction

H = comm.DBPSKDemodulator creates a demodulator System object™, H. This object demodulates the input signal using the differential binary phase shift keying (DBPSK) method.

H = comm.DBPSKDemodulator(Name,Value) creates a DBPSK demodulator 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.DBPSKDemodulator(PHASE,Name,Value) creates a DBPSK demodulator object, H. This object has the PhaseRotation property set to PHASE and the other specified properties set to the specified values.

Properties

PhaseRotation

Additional phase shift

Specify the additional phase difference between previous and current modulated bits in radians as a real scalar. The default is 0. This value corresponds to the phase difference between previous and current modulated bits when the input is zero.

OutputDataType

Data type of output

Specify output data type as one of Full precision | Smallest unsigned integer | double | single | int8 | uint8 | int16 | uint16 | int32 | uint32 | logical. The default is Full precision. When you set this property to Full precision, the output data type has the same data type as the input. In this case, that value must be a double- or single-precision data type.

Methods

cloneCreate DBPSK demodulator 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 DBPSK demodulator object
stepDemodulate using DBPSK method

Examples

Modulate and demodulate a signal using DBPSK modulation.

    hMod = comm.DBPSKModulator(pi/4);
    hAWGN = comm.AWGNChannel('NoiseMethod', ...
                         'Signal to noise ratio (SNR)','SNR',15);
    hDemod = comm.DBPSKDemodulator(pi/4);
% Create an error rate calculator, account for the one bit transient caused by the differential modulation
    hError = comm.ErrorRate('ComputationDelay',1);
    for counter = 1:100
        % Transmit a 50-symbol frame
        data = randi([0 1],50,1);
        modSignal = step(hMod, data);
        noisySignal = step(hAWGN, modSignal);
        receivedData = step(hDemod, noisySignal);
        errorStats = step(hError, data, receivedData);
    end
    fprintf('Error rate = %f\nNumber of errors = %d\n', ...
      errorStats(1), errorStats(2))

Algorithms

This object implements the algorithm, inputs, and outputs described on the DBPSK Demodulator Baseband block reference page. The object properties correspond to the block parameters.

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