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BPSK Modulator Baseband

Modulate using BPSK method

  • Library:
  • Communications Toolbox / Modulation / Digital Baseband Modulation / PM

    Communications Toolbox HDL Support / Modulation / PM

  • BPSK Modulator Baseband block


The BPSK Modulator Baseband block modulates a signal by using the binary phase shift keying (BPSK) method. The output is a baseband representation of the modulated signal. The input signal must be a discrete-time binary-valued signal. If the input bit is 0 or 1, then the modulated symbol is exp(jθ) or -exp(jθ), respectively. The Phase offset (rad) parameter specifies the value of θ in radians.



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Input signal, specified as a scalar or vector with element values in the range [0,M – 1], where M is the modulation order. If you specify a binary vector, the number of elements must be an integer multiple of the number of bits per symbol. The number of bits per symbol is equal to log2(M).

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean
Complex Number Support: Yes


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BPSK-modulated baseband signal, returned as a complex-valued scalar or vector.

Data Types: single | double | fixed point


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Phase offset of the zeroth point of the constellation in radians, specified as a scalar.

Example: pi/4

Data Types

Output data type, specified as one of these options.

  • double

  • single

  • Inherit via back propagation — The block matches the output data type and scaling to the next block in the model

  • fixdt(1,16)

  • fixdt(1,16,0)

  • <data type expression> — Enables parameters for which you specify additional details

Block Characteristics

Data Types

Boolean | double | fixed pointa, b | integer | single

Multidimensional Signals


Variable-Size Signals


a ufix(ceil(log2(M))) only at the input for M-ary modulation.

b Fixed-point outputs must be signed.

More About

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Phase modulation is a linear baseband modulation technique in which the message modulates the phase of a constant amplitude signal. Binary Phase Shift Keying (BPSK) is a two phase modulation scheme, where the 0’s and 1’s in a binary message are represented by two different phase states in the carrier signal


for (n1)TbtnTb, n=1,2, 3,where:

  • ϕn = πm, m∈{0,1}.

  • Eb is the energy per bit.

  • Tb is the bit duration.

  • fc is the carrier frequency.

In MATLAB®, the baseband representation of a BPSK signal is


The BPSK signal has two phases: 0 and π. The probability of a bit error in an AWGN channel is


where N0 is the noise power spectral density.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a