Range Response
Range response
Libraries:
Phased Array System Toolbox /
Detection
Description
The Range Response block performs range filtering on fast-time (range) data, using either a matched filter or an FFT-based algorithm. The output is typically used as input to a detector. Matched filtering improves the SNR of pulsed waveforms. For continuous FM signals, FFT processing extracts the beat frequency of FMCW waveforms. Beat frequency is directly related to range.
The input to the block is a radar data cube. The organization of the data cube follows the Phased Array System Toolbox™ convention. The first dimension of the cube represents the fast time samples or ranges of the received signals. The second dimension represents multiple spatial channels such as different sensors or beams. The third dimension, slow time, represent pulses. Range filtering operates along the fast-time dimension of the cube. Processing along the other dimensions is not performed. If the data contains only one channel or pulse, the data cube can contain fewer than three dimensions. Because this object performs no Doppler processing, you can use it to process noncoherent radar pulses.
The output of the block is also a data cube with the same number of dimensions as the input. Its first dimension contains range-processed data but its length can differ from the first dimension of the input data cube.
Ports
Input
X — Input data cube
complex-valued K-by-1 column vector | complex-valued K-by-L matrix | complex-valued K-by-N-by-L array
Input data cube, specified as a complex-valued K-by-1 column vector, a complex-valued K-by-L matrix, or a complex-valued K-by-N-by-L array.
K is the number of range or time samples.
N is the number of independent channels such as sensors or directions.
L is the number of pulses or sweeps in the input signal.
Each K-element column vector is processed independently.
For an FMCW waveform, with a triangle sweep, the sweeps alternate between positive and negative slopes. However, Range Response is designed to process consecutive sweeps of the same slope. To apply the Range Response block for a triangle-sweep system, use one of the following approaches:
Specify a positive Sweep slope parameter value, with
X
corresponding to upsweeps only. After obtaining the Doppler or speed values, divide them by 2.Specify a negative Sweep slope parameter value, with
X
corresponding to downsweeps only. After obtaining the Doppler or speed values, divide them by 2.
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.
Data Types: double
Complex Number Support: Yes
Coeff — Matched filter coefficients
complex-valued column vector
Matched filter coefficients, specified as a complex-valued column vector. The length of the vector must be less than or equal to the number of rows in the input data, K.
Dependencies
To enable this port, set Range processing method to Matched
filter
.
Data Types: double
Complex Number Support: Yes
XRef — Reference signal
complex-valued K-by-1 column vector
Reference signal used for dechirping the input signal, specified
as a complex-valued K-by-1 column vector. The
number of rows must equal the length of the first dimension of X
.
Dependencies
To enable this port, set Range processing method to FFT
and
select the Dechirp input signal parameter.
Data Types: double
Complex Number Support: Yes
Output
Resp — Range response data cube
complex-valued M-element column vector | complex-valued M-by-L matrix | complex-valued M-by-N by-L array
Range response data cube, returned as a
Complex-valued M-element column vector
Complex-valued M-by-L matrix
Complex-valued M-by-N by-L array
See Radar Data Cube Concept. The value of M depends on the type of processing
Range processing method | Dechirp input signal | Value of M |
---|---|---|
FFT | off | If you set the Source of FFT length in range
processing to |
on | M equals the number of rows, K, of the input signal. | |
Matched filter | N/A | M equals the number of rows, K, of the input signal. |
Data Types: double
Complex Number Support: Yes
Range — Range values along range dimension
real-valued M-by-1 column vector
Range values along the first dimension of the Resp output
data port, specified as a real-valued M-by-1 column
vector. This quantity defines the range values along the first dimension
of the Resp
output port data. Units are in meters.
Data Types: double
Parameters
Range processing method — Range processing method
Matched filter
(default) | FFT
Range processing method, specified as Matched filter
or FFT
.
Matched filter | The block applies a matched filter to the incoming signal. This approach is commonly used for pulsed signals, where the matched filter is the time reverse of the transmitted signal. |
FFT | The block applies an FFT to the input signal. This approach is commonly used for FMCW and linear FM pulsed signals. |
Data Types: char
Propagation speed (m/s) — Signal propagation speed
physconst('LightSpeed')
(default) | positive scalar
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
Inherit sample rate — Inherit sample rate from upstream blocks
on (default) | off
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
Sample rate (Hz) — Sampling rate of signal
1e6
(default) | positive real-valued scalar
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
FM sweep slope (Hz/s) — FM sweep slope
1e9
(default) | scalar
Specify the slope of the linear FM sweep as a scalar. This parameter
must match the actual sweep of the input data in port X
.
Dependencies
To enable this parameter, set Range processing method to FFT
.
Data Types: double
Dechirp input signal — Enable dechirping of input signal
on
(default) | off
Select this parameter to enable dechirping of input signal.
Dependencies
To enable this parameter, set Range processing method to FFT
.
Data Types: Boolean
Source of FFT length in range processing — Source of FFT length for range processing
Auto
(default) | Property
Source of FFT length for range processing, specified as Auto
or Property
Auto | The FFT length equals the number of rows of the input data cube. |
Property | Specify FFT length in the FFT length in range processing parameter. |
Dependencies
To enable this parameter, set Range processing method to
FFT
.
Data Types: char
FFT length in range processing — Range processing FFT length
1024
(default) | positive integer
FFT length for range processing, specified as a positive integer.
Dependencies
To enable this parameter, set Range processing method to FFT
and Source
of FFT length in range processing to Property
.
Data Types: double
Range processing window — Range FFT weighting window
None
(default) | Hamming
| Chebyshev
| Hann
| Kaiser
| Taylor
Range FFT weighting window, specified as None
, Hamming
, Chebyshev
, Hann
, Kaiser
,
or Taylor
.
If you set this property to Taylor
, the generated
Taylor window has four nearly constant sidelobes next to the mainlobe.
Dependencies
To enable this parameter, set Range processing method to FFT
.
Data Types: char
Range sidelobe attenuation level — Sidelobe attenuation for range processing
30
(default) | positive scalar
Sidelobe attenuation for range processing, specified as a positive scalar. Units are in dB.
Dependencies
To enable this parameter, set Range processing method to FFT
and Range
processing window to Kaiser
, Chebyshev
,
or Taylor
.
Data Types: double
Set reference range at center — Set reference range at center of range grid
on
(default) | off
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.
Dependencies
To enable this property, set the Range processing
method to FFT
.
Reference range (m) — Reference range of range grid
0.0
(default) | nonnegative scalar
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.
Example: 1000.0
Data Types: double
Simulate using — Block simulation method
Interpreted Execution
(default) | Code Generation
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 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).
Programmatic Use
Block
Parameter:SimulateUsing |
Type:enum |
Values:Interpreted
Execution , Code Generation |
Default:Interpreted
Execution |
References
[1] Richards, M. Fundamentals of Radar Signal Processing, 2nd ed. McGraw-Hill Professional Engineering, 2014.
[2] Richards, M., J. Scheer, and W. Holm, Principles of Modern Radar: Basic Principles. SciTech Publishing, 2010.
Version History
Introduced in R2017a
See Also
Blocks
Functions
Objects
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