The linear FM waveform is popular in radar systems because its large time-bandwidth product can provide good range resolution. However, the large bandwidth of this waveform makes digital matched filtering difficult because it requires expensive, high-quality analog-to-digital converters. Stretch processing, also known as deramping, or dechirping, is an alternative to matched filtering. Stretch processing provides pulse compression by looking for the return within a predefined range interval of interest. Stretch processing typically occurs in the analog domain. Unlike matched filtering, stretch processing reduces the bandwidth requirement of subsequent processing.
phased.StretchProcessor System object™ implements
stretch processing. You can use this object as part of a simulation
phased.LinearFMWaveform or directly with
your own data.
The typical procedure for stretch processing is as follows:
Choose a range interval of interest, centered on a reference range. Stretch processing focuses on this interval instead of the entire range span that the pulse can cover.
Define and configure a stretch processor object. The configuration includes the reference range, length of the range interval of interest, characteristics of the linear FM waveform, and signal propagation speed.
If you are using a
to implement the linear FM waveform, use the
to define and automatically configure a stretch processor object.
Otherwise, create a
directly, and set its properties as needed.
Perform stretch processing by calling the
on your stretch processor object. You provide your received signal
as an input argument. The
step method generates a
reference signal and correlates it with your received signal.
Compute a periodogram of the output from
and identify the peak frequencies. You can use the following features
to help you perform this step:
Convert each peak frequency to the corresponding range
value, using the