Modulate using BPSK method


The BPSKModulator object modulates using the binary phase shift keying method. The output is a baseband representation of the modulated signal.

To modulate a binary phase shift signal:

  1. Define and set up your BPSK modulator object. See Construction.

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


Starting in R2016b, instead of using the step method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, y = step(obj,x) and y = obj(x) perform equivalent operations.


H = comm.BPSKModulator creates a modulator System object, H, that modulates the input signal using the binary phase shift keying (BPSK) method.

H = comm.BPSKModulator(Name,Value) creates a BPSK modulator 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.BPSKModulator(PHASE,Name,Value) creates a BPSK modulator object, H. The object's PhaseOffset property is set to PHASE, and the other specified properties are set to the specified values.



Phase of zeroth point of constellation

Specify the phase offset of the zeroth point of the constellation, in radians, as a finite, real scalar. The default is 0.


Data type of output

Specify the output data type as one of double | single | Custom. The default is double.

 Fixed-Point Properties


constellationCalculate or plot ideal signal constellation
stepModulate using BPSK method
Common to All System Objects

Allow System object property value changes


collapse all

This example creates binary data, modulates it, and then displays the data using a scatter plot.

Create binary data symbols

data = randi([0 1],100,1);

Create a BPSK modulator System object

bpskModulator = comm.BPSKModulator;

Change the phase offset to pi/16

bpskModulator.PhaseOffset = pi/16;

Modulate and plot the data

modData = bpskModulator(data);


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

Extended Capabilities

Introduced in R2012a