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Phase Coded Waveform

Phase-coded pulse waveform

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  • Phase Coded Waveform block

Libraries:
Phased Array System Toolbox / Waveforms

Description

The Phase-Coded Waveform block generates samples of a phase-coded pulse waveform with specified chip width, pulse repetition frequency (PRF), and phase code. The block outputs an integer number of pulses or samples.

Ports

Input

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Index to select the pulse repetition frequency (PRF), specified as a positive integer. The index selects the PRF from the predefined vector of values specified by the Pulse repetition frequency (Hz) parameter.

Example: 4

Dependencies

To enable this port, select Enable PRF selection input.

Data Types: double

Frequency offset in Hz, specified as a scalar.

Example: 2e3

Dependencies

To enable this port, set Source of Frequency Offset to Input port.

Data Types: double

Output

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Pulse waveform samples, returned as a complex-valued vector.

Data Types: double

Pulse repetition frequency of current pulse, returned as a positive scalar.

Dependencies

To enable this port, set the Output signal format parameter to Pulses and then select the Enable PRF output parameter.

Data Types: double

Matched filter coefficients, returned as a vector.

Dependencies

To enable this port, select Enable Matched Filter Coefficients Output.

Data Types: double
Complex Number Support: Yes

Parameters

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Sample rate of the output waveform, specified as a positive scalar. Set the ratio of the Sample rate (Hz) parameter to the Pulse repetition frequency (Hz) parameter to an integer.

  • The ratio of Sample rate (Hz) to each element in the Pulse repetition frequency (Hz) vector must be an integer. This restriction is equivalent to requiring that the pulse repetition interval is an integral multiple of the sample interval.

  • The product of Sample rate (Hz) and Chip width (s) must be an integer. This restriction is equivalent to requiring that the chip width is an integer multiple of the sample interval.

Units are in Hz.

Example: 5e3

Code type used for phase modulation, specified as one of

  • Barker

  • Frank

  • P1

  • P2

  • P3

  • P4

  • Px

  • Zadoff-Chu

  • Maximum Length Sequence

  • Quadratic Residue Sequence

  • Custom

Example: P2

Custom phase code, specified as a length-M vector of complex values. Each element in the specified vector corresponds to a single chip.

Example: [j,2/3,-j]

Dependencies

To enable this parameter, set the Code parameter to 'Custom'.

Data Types: double
Complex Number Support: Yes

Duration of every chip in a phase-coded waveform, specified as a positive scalar. The value of this parameter must satisfy these constraints:

  • The product of Chip width (s), Number of chips, and Pulse repetition frequency (Hz) must be less than or equal to one. This restriction is equivalent to requiring that the pulse length is less than the pulse repetition interval.

  • The product of Sample rate (Hz) and Chip width (s) must be an integer. This restriction is equivalent to requiring that the chip width is an integer multiple of the sample interval.

Units are in seconds.

Example: 2e-4

Number of chips in a phase-coded waveform, specified as a positive integer. The product of the Chip width (s), Number of chips, and Pulse repetition frequency (Hz) parameters must be less than or equal to one. This restriction is equivalent to requiring that the chip width is an integer multiple of the sample interval.

The table shows additional constraints on the number of chips for different code types.

If the Phase code parameter is...Then the Number of chips parameter must be...
Frank, P1, or PxA perfect square
P2An even number that is a perfect square
Barker2, 3, 4, 5, 7, 11, or 13
'Maximum Length Sequence'7, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, and 8191
'Quadratic Residue Sequence'A prime number of the form 4n-1, where n is an integer

Example: 9

Dependencies

To enable this parameter, set the Code parameter to anything other than 'Custom'.

Sequence index for Zadoff-Chu code type, specified as a positive integer. The values of the Zadoff-Chu sequence index and the Number of chips parameters must be relatively prime.

Example: 2

Dependencies

To enable this parameter, set Phase Code to Zadoff-Chu.

Pulse repetition frequency, PRF, specified as a scalar or a row vector. Units are in Hz. The pulse repetition interval, PRI, is the inverse of the pulse repetition frequency, PRF. The value of Pulse repetition frequency (Hz) must satisfy these constraints:

  • The product of Pulse width and Pulse repetition frequency (Hz) must be less than or equal to one. This condition expresses the requirement that the pulse width is less than one pulse repetition interval. For the phase-coded waveform, the pulse width is the product of the chip width and number of chips.

  • The ratio of sample rate to any element of Pulse repetition frequency must be an integer. This condition expresses the requirement that the number of samples in one pulse repetition interval is an integer.

You can select the value of PRF by using block parameter settings alone or in conjunction with the input port, PRFIdx.

  • When the Enable PRF selection input parameter is not selected, set the PRF using block parameters.

    • To implement a constant PRF, specify Pulse repetition frequency (Hz) as a positive scalar.

    • To implement a staggered PRF, specify Pulse repetition frequency (Hz) as a row vector with positive values. After the waveform reaches the last element of the vector, the process continues cyclically with the first element of the vector. When PRF is staggered, the time between successive output pulses cycles through the successive values of the PRF vector.

  • When the Enable PRF selection input parameter is selected, you can implement a selectable PRF by specifying Pulse repetition frequency (Hz) as a row vector with positive real-valued entries. But this time, when you execute the block, select a PRF by passing an index into the PRF vector into the PRFIdx port.

In all cases, the number of output samples is fixed when you set the Output signal format to Samples. When you use a varying PRF and set Output signal format to Pulses, the number of output samples can vary.

Programmatic Use

Block Parameter:PRF
Type:double
Values:positive scalar
Default:1e6

Select this parameter to enable the PRFIdx port.

  • When enabled, pass in an index into a vector of predefined PRFs. Set predefined PRFs using the Pulse repetition frequency (Hz) parameter.

  • When not enabled, the block cycles through the vector of PRFs specified by the Pulse repetition frequency (Hz) parameter. If Pulse repetition frequency (Hz) is a scalar, the PRF is constant.

Programmatic Use

Block Parameter:PRFSelectionInputPort
Type:logical
Values:positive scalar
Default:off

Source of frequency offset, specified as Property or Input port.

  • When set to Property, the offset is determined by the value of the Frequency Offset parameter.

  • When set to Input port, the offset is determined by the value of the FreqOffset port.

Programmatic Use

Block Parameter:FrequencyOffsetSource
Type:enum
Values:Property, Input Port
Default:Property

Frequency offset, specified as a scalar. Units are in Hz.

Example: 2e3

Dependencies

To enable this parameter set the Source of Frequency Offset parameter to Input port.

Programmatic Use

Block Parameter:FrequencyOffset
Type:double
Values:scalar
Default:0

Source of simulation sample time, specified as Derive from waveform parameters or Inherit from Simulink engine. When set to Derive from waveform parameters, the block runs at a variable rate determined by the PRF of the selected waveform. The elapsed time is variable. When set to Inherit from Simulink engine, the block runs at a fixed rate so the elapsed time is a constant.

Dependencies

To enable this parameter, select the Enable PRF selection input parameter.

Programmatic Use

Block Parameter:SimulationTimeSource
Type:enum
Values:Derive from waveform parameters, Inherit from Simulink engine
Default:Derive from waveform parameters

The format of the output signal, specified as Pulses or Samples.

If you set this parameter to Samples, the output of the block consists of multiple samples. The number of samples is the value of the Number of samples in output parameter.

If you set this parameter to Pulses, the output of the block consists of multiple pulses. The number of pulses is the value of the Number of pulses in output parameter.

Programmatic Use

Block Parameter:OutputFormat
Type:enum
Values:Pulses Samples
Default:Pulses

Number of samples in the block output, specified as a positive integer.

Example: 1000

Dependencies

To enable this parameter, set the Output signal format parameter to Samples.

Programmatic Use

Block Parameter:NumSamples
Type:double
Values:positive scalar
Default:100

Data Types: double

Number of pulses in the block output, specified as a positive integer.

Example: 2

Dependencies

To enable this parameter, set the Output signal format parameter to Pulses.

Programmatic Use

Block Parameter:NumPulses
Type:double
Values:positive scalar
Default:1

Data Types: double

Select this parameter to enable the PRF output port.

Dependencies

To enable this parameter, set Output signal format to Pulses.

Programmatic Use

Block Parameter:PRFOutputPort
Type:enum
Values:off on
Default:off

Select this parameter to enable the Coeff output port.

Programmatic Use

Block Parameter:CoefficientOutputPort
Type:enum
Values:off on
Default:off

Block simulation, specified as Interpreted Execution or Code Generation. If you want your block to use the MATLAB® interpreter, choose Interpreted Execution. If you want your block to run as compiled code, choose Code Generation. Compiled code requires time to compile but usually runs faster.

Interpreted execution is useful when you are developing and tuning a model. The block runs the underlying System object™ in MATLAB. You can change and execute your model quickly. When you are satisfied with your results, you can then run the block using Code Generation. Long simulations run faster with generated code than in interpreted execution. You can run repeated executions without recompiling, but if you change any block parameters, then the block automatically recompiles before execution.

This table shows how the Simulate using parameter affects the overall simulation behavior.

When the Simulink® model is in Accelerator mode, the block mode specified using Simulate using overrides the simulation mode.

Acceleration Modes

Block SimulationSimulation Behavior
NormalAcceleratorRapid Accelerator
Interpreted ExecutionThe block executes using the MATLAB interpreter.The block executes using the MATLAB interpreter.Creates a standalone executable from the model.
Code GenerationThe block is compiled.All blocks in the model are compiled.

For more information, see Choosing a Simulation Mode (Simulink).

Programmatic Use

Block Parameter:SimulateUsing
Type:enum
Values:Interpreted Execution, Code Generation
Default:Interpreted Execution

Version History

Introduced in R2014b

See Also