Range Doppler Response

Range-Doppler response

Library

Detection

phaseddetectlib

• 

×

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.

Parameters

Range processing method

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 (m/s)

Specify the propagation speed of the signal, in meters per second, as a positive scalar.

Source of pulse repetition frequency

Source of pulse repetition frequency, specified 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.

Pulse repetition frequency of the input signal (Hz)

Pulse repetition frequency of the input signal, specified 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.

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

Inherit sample rate

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

Sample rate (Hz)

Specify the signal sampling rate (in hertz) as a positive scalar. This parameter appears only when the Inherit sample rate parameter is not selected.

Source of FFT length in Doppler processing

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.

FFT length in Doppler processing

This parameter appears only when you set Source of FFT length in Doppler processing to Property. Specify the length of the FFT used in Doppler processing as a positive integer.

Doppler processing window

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.

Doppler sidelobe attenuation level

This parameter appears only when Doppler processing window is set to Kaiser, Chebyshev, or Taylor. Specify the sidelobe attenuation level as a positive scalar, in decibels.

Doppler output

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 (Hz)

This parameter appears only when you set Doppler output to Speed. Specify the carrier frequency, in hertz, as a scalar.

FM sweep slope (Hz/s)

This parameter appears only when you set Range processing method to FFT. Specify the slope of the linear FM sweeping, in hertz per second, as a scalar.

Dechirp input signal

This check box 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.

Source of FFT length in range processing

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.

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

FFT length in range processing

This parameter appears only when you set Range processing method to FFT and Source of FFT length in range processing to Property. Specify the FFT length in the range domain as a positive integer.

Range processing window

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

Set reference range at center

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.

Reference range (m)

Reference range of the range grid, specified 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.

Range sidelobe attenuation level

This parameter appears only when you set Range processing method to FFT and Range processing window to Kaiser, Chebyshev, or Taylor. Specify the sidelobe attenuation level as a positive scalar, in decibels.

Simulate using

Block simulation method, 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 than they would in interpreted execution. You can run repeated executions without recompiling. However, if you change any block parameters, then the block automatically recompiles before execution.

When setting this parameter, you must take into account the overall model simulation mode. The table shows how the Simulate using parameter interacts with the overall simulation mode.

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

Acceleration Modes

Block Simulation	Simulation Behavior
	Normal	Accelerator	Rapid Accelerator
Interpreted Execution	The block executes using the MATLAB interpreter.	The block executes using the MATLAB interpreter.	Creates a standalone executable from the model.
Code Generation	The block is compiled.	All blocks in the model are compiled.

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

Ports

Note

The block input and output ports correspond to the input and output parameters described in the step method of the underlying System object. See link at the bottom of this page.

Port	Description	Supported Data Types
X	Input signal. The size of the first dimension of the input matrix can vary to simulate a changing signal length. A size change can occur, for example, in the case of a pulse waveform with variable pulse repetition frequency. Signal lengths can vary when you use pulse waveforms. Then you can only apply the Matched filter option of the Range processing method parameter.	Double-precision floating point
Coeff	Matched-filter coefficients.	Double-precision floating point
XRef	Reference signal	Double-precision floating point
PRF	Pulse repetition frequency	Double-precision floating point
Resp	Range-Doppler response.	Double-precision floating point
Range	Range grid.	Double-precision floating point
Dop	Doppler grid.	Double-precision floating point