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Phase Extractor

Extract the unwrapped phase of a complex input

  • Phase Extractor block

DSP System Toolbox / Signal Operations


The Phase Extractor block extracts the unwrapped phase of a complex input.



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Specify the input signal as a vector or a matrix. When the input is a matrix, the block treats each column of the signal as an independent channel. The first dimension is the length of the channel. The second dimension is the number of channels. The block treats one dimensional inputs as one channel.

Data Types: single | double
Complex Number Support: Yes


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The block returns the unwrapped phase of the signal.

The block preserves the input size and dimension, and the output port rate equals the input port rate.

Data Types: single | double


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When you clear this check box, the block ignores boundaries between the input frames. When you select this check box, the block treats each frame of input data independently, and resets the initial phase value for each new input frame.

Specify the type of simulation to run as one of the following:

  • Code generation –– Simulate model using generated C code. The first time you run a simulation, Simulink® generates C code for the block. The C code is reused for subsequent simulations, as long as the model does not change. This option requires additional startup time but provides faster simulation speed than Interpreted execution.

  • Interpreted execution –– Simulate model using the MATLAB®  interpreter. This option shortens startup time but has slower simulation speed than Code generation.

Block Characteristics

Data Types

double | single

Direct Feedthrough


Multidimensional Signals


Variable-Size Signals


Zero-Crossing Detection



Consider an input frame of length N:


The step method acts on this frame and produces this output:




Here, i runs from 1 to N. The angle function returns the phase angle in radians.

If the input signal consists of multiple frames:

  • If you set TreatFramesIndependently to true, the step method treats each frame independently. Therefore, in each frame, the step method calculates the phase using the preceding formula where:

    • Φ0 is 0.

    • x0 is 1.

  • If you set TreatFramesIndependently to false, the step method ignores boundaries between frames. Therefore, in each frame, the step method calculates the phase using the preceding formula where:

    • Φ0 is the last unwrapped phase from the previous frame.

    • x0 is the last sample from the previous frame.

Extended Capabilities

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

Version History

Introduced in R2014b

See Also