Stretch Processor
Stretch processor for linear FM waveforms
![](stretch_processor_icon_0.png)
Libraries:
Phased Array System Toolbox /
Detection
Description
The Stretch Processor block applies stretch processing on a linear FM waveform. Also known as dechirping, stretch processing is an alternative to matched filtering for linear FM waveforms.
Ports
Input
X — Input signal
M-by-P complex-valued
matrix
Input signal, specified as an M-by-P complex-valued array. M is the number of samples and P is the number of pulses.
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
PRF — Pulse repetition frequency
positive scalar
Pulse repetition frequency of current pulse, specified as a positive scalar.
Dependencies
To enable this port, set the Specify PRF as
parameter to Input port
.
Data Types: double
Output
Y — Stretch processed signal
M-by-P complex-valued
matrix
Stretch processed signal, returned as an M-by-P complex-valued array. M is the number of samples and P is the number of pulses.
Data Types: double
Complex Number Support: Yes
Parameters
Pulse width (s) — Time duration of pulse
50e-6
(default) | positive scalar
The duration of each pulse, specified as a positive scalar. Set the product of Pulse width (s) and Pulse repetition frequency to be less than or equal to one. This restriction ensures that the pulse width is smaller than the pulse repetition interval. Units are in seconds.
Example: 300e-6
Specify PRF as — Source of PRF value
Property
(default) | Auto
| Input port
Source of PRF value for the stretch processor, specified as
Property
, Auto
, or
Input port
. When set to
Property
, the Pulse repetition frequency
(Hz) parameter sets the PRF. When set to Input
port
, pass in the PRF using the PRF
input port.
When set to Auto
, PRF is computed from the number of rows in
the input signal.
.
Pulse repetition frequency (Hz) — Pulse repetition frequency
1e4
(default) | positive scalar
Pulse repetition frequency, PRF, specified as a positive scalar. Units are in Hertz.
Set this parameter to the same value set in any Waveform
library
block used in the simulation.
Dependencies
To enable this parameter, set the Specify PRF as parameter to
Property
.
FM sweep slope (Hz/s) — Slope of linear FM sweep
2e9
(default) | scalar
Slope of the linear FM sweeping as a scalar, specified as a scalar. Units are in Hertz per second.
Example: 1e3
FM sweep interval — Direction of FM sweep
Positive
(default) | Symmetric
FM sweep interval, specified as Positive
or
Symmetric
. If you set this parameter value to
Positive
, the waveform sweeps the frequency
bandwidth between 0 and B, where
B is the frequency bandwidth. If you set this
parameter value to Symmetric
, the waveform sweeps
in the interval between –B/2 and
B/2.
Signal propagation speed (m/s) — Signal propagation speed
physconst('LightSpeed')
(default) | real-valued 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')
. Units are in meters per second.
Example: 3e8
Data Types: double
Reference range (m) — Center of ranges of interest
5000
(default) | positive scalar
Center of ranges of interest, specified as a positive scalar. The reference range must be within the unambiguous range of one pulse. Units are in meters.
Example: 10e3
Reference span (m) — Span of ranges of interest
500
(default) | positive scalar
Span of ranges of interest, specified as a positive scalar. The span of ranges is centered on the range specified by the Reference range (m) parameter. Units are in meters.
Example: 1e3
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 |
Version History
Introduced in R2014b
See Also
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