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Range Doppler Response

Range-Doppler response

  • Library:
  • Phased Array System Toolbox / Detection

  • Range Doppler Response block

Description

The Range-Doppler Response block computes the range-Doppler map of an input signal. The output response is a matrix whose rows represent range gates and whose columns represent Doppler bins.

Ports

Input

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Input data, specified as a complex-valued K-by-L matrix or K-by-N-by-L array where

  • K denotes the number of fast-time samples.

  • N denotes the number of channels such as beams or sensors. When N is one, only a single data channel is present.

  • L denotes the number of pulses for matched-filter processing and the number of sweeps for FFT processing.

Data Types: single | double

Matched filter coefficients, specified as a column vector.

Dependencies

To enable this port, set the Range processing method to Matched filter.

Data Types: single | double

Reference signal, specified as a

Dependencies

To enable this port, set the Range processing method to FFT and then select the Dechirp input signal check box.

Data Types: double

Pulse repetition frequency, specified as a positive scalar. prf must be less than or equal to the sample rate specified in the SampleRate property divided by the length of the first dimension of the input signal, x. You can specify this argument as single or double precision.

Dependencies

To enable this port, set the Source of pulse repetition frequency drop down menu to Input port.

Data Types: double

Output

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Range-Doppler, returned as a complex-valued M-by-P matrix or an M-by-N-by-P array.

Range samples at which the range-Doppler response is evaluated. The output is a column vector of length M.

Data Types: double

Doppler samples or speed samples at which the range-Doppler response is evaluated. returned as a column vector of length P. Whether Dop contains Doppler or speed samples depends on the Doppler output parameter.

Data Types: double

Parameters

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Specify the method of range processing as Matched filter or FFT

Matched filter Applies a matched filter to the incoming signal. This technique is commonly used for pulsed signals, where the matched filter is the time reverse of the transmitted signal. Choosing this option creates the Coeff input port.
FFT Performs range processing by applying an FFT to the input signal. This approach is commonly used with FMCW and linear FM pulsed signals.

Signal propagation speed, specified as a real-valued positive scalar. The default value of the speed of light is the value returned by physconst('LightSpeed').

Data Types: double

Select this parameter to inherit the sample rate from upstream blocks. Otherwise, specify the sample rate using the Sample rate (Hz) parameter.

Data Types: Boolean

Specify the signal sampling rate as a positive scalar. Units are in Hz.

Dependencies

To enable this parameter, clear the Inherit sample rate check box.

Data Types: double

Specify the reference range of the range grid as a nonnegative scalar.

  • If you set the Range processing method parameter to Matched filter, the reference range is set to the start of the range grid.

  • If you set the Range processing method property to FFT, the reference range depends on the Set reference range at center check box.

    • When you select the Set reference range at center check box, the reference range is set to the center of the range grid.

    • If you do not select the Set reference range at center check box, the reference range is set to the start of the range grid.

    Units are in meters.

Specify the source of pulse repetition frequency as

  • Auto — automatically compute the pulse repetition frequency (PRF). The PRF is the sample rate of the signal divided by the number of rows in the input port signal, X.

  • Property— specify the pulse repetition frequency using the PRF parameter.

  • Input port— specify the PRF using the PRF input port.

Use the Property or Input port option when the pulse repetition frequency cannot be determined by the signal duration, as is the case with range-gated data.

Specify the pulse repetition frequency of the input signal as a positive scalar. PRF must be less than or equal to the sample rate divided by the number of rows of the input signal. When the signal length is variable, use the maximum possible number of rows of the input signal instead.

Dependencies

To enable this parameter, set the Source of pulse repetition frequency parameter to Property.

Specify how the block determines the length of the FFT used in Doppler processing. Values of this parameter are

Auto The FFT length equals the number of rows of the input signal.
Property The FFT length in Doppler processing parameter of this block specifies the FFT length.

Specify the length of the FFT used in Doppler processing as a positive integer.

Dependencies

This parameter appears only when you set Source of FFT length in Doppler processing to Property.

Specify the window used for Doppler processing using one of

None
Hamming
Chebyshev
Hann
Kaiser
Taylor

If you set this parameter to Taylor, the generated Taylor window has four nearly-constant sidelobes adjacent to the mainlobe.

Specify the sidelobe attenuation level as a positive scalar, in decibels.

Dependencies

This parameter appears only when Doppler processing window is set to Kaiser, Chebyshev, or Taylor.

Specify the Doppler domain output as Frequency or Speed

Frequency Doppler shift, in hertz.
Speed Radial speed corresponding to Doppler shift, in meters per second.

Signal carrier frequency, specified as a positive real-valued scalar. Units are in hertz.

Data Types: double

Specify the slope of the linear FM sweeping, in hertz per second, as a scalar.

Dependencies

This parameter appears only when you set Range processing method to FFT.

Select this check box to make the block perform the dechirp operation on the input signal. Clear this check box to indicate that the input signal is already dechirped and no dechirp operation is necessary.

Dependencies

This check box appears only when you set Range processing method to FFT.

Specify how the block determines the FFT length in range processing. Values of this parameter are

Auto The FFT length equals the number of rows of the input signal.
Property The FFT length is specified by FFT length in range processing .

Dependencies

This parameter appears only when you set Range processing method to FFT.

Specify the FFT length in the range domain as a positive integer.

Dependencies

This parameter appears only when you set Range processing method to FFT and Source of FFT length in range processing to Property.

Specify the window used for range processing using one of

None
Hamming
Chebyshev
Hann
Kaiser
Taylor

If you set this parameter to Taylor, the generated Taylor window has four nearly-constant sidelobes adjacent to the mainlobe.

Dependencies

This parameter appears only when you set Range processing method to FFT.

Set reference range at the center of range grid, specified as on or off. Selecting this check box, enables you to set the reference range at the center of the range grid. Otherwise, the reference range is set to the beginning of the range grid.

Specify the sidelobe attenuation level as a positive scalar, in decibels.

Dependencies

This parameter appears only when you set Range processing method to FFT and Range processing window to Kaiser, Chebyshev, or Taylor.

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).

Version History

Introduced in R2014b