hi my name is Rick Gentile on the
product manager for the phased array
system tool box I want to show you how
easy it is to generate a radar data cube
using MATLAB in the phased array system
tool box you could find a good
description of the radar data cube and
fundamentals of radar signal processing
by Mark Richards in this book he
describes the radar data cube it's a
convenient way to represent a collection
of received radar signals built up
sample by sample in space and time once
the receive data is put into this data
cube format various signal processing
techniques can be used to enhance the
target returns and extract range speed
and bearing information from the data
these techniques include algorithms such
as pulse compression doppler processing
and beam forming so to build up a radar
data cube will need a few things we'll
start with a single pulse that's
reflected off the target the received
data is sampled in time the samples can
be used to calculate the distance to the
target these time samples are sometimes
called range bins they make up the
y-axis of the data cube this is referred
to as the fast time dimension because
the sampling rate can sometimes be
pretty high from the tens of megahertz
to a gigahertz or higher a single radar
target reflection will often be
collected at an array of receive
elements each one of these elements
makes up an individual channel which
makes up the X dimension of the radar
data cube in the figure spatially
sampling the receive signals like this
will allow us to determine the bearing
of the target if we use algorithms like
beam forming and direction of arrival
estimation you might be transmitting and
receiving multiple pulses in a selected
direction at a rate called the pulse
repetition frequency the time base for a
collection of pulses is sometimes called
the coherent processing interval this
will be a much slower rate than the
range gate sampling so pulse repetition
frequency of 1 to 10 kilohertz would be
a typical range this is the dimension of
the radar data cube it is sometimes
called a slow time dimension the
information you get from this collection
of data is something you can use to
determine the speed of the target well
let's take a look at how we can do this
in matlab ok we'll see that it's
relatively easy to generate pulse
waveforms reflect the pulses Offit are
and collect the receive signals into the
radar data cube here's the MATLAB code
that we can use to build our own radar
data cube we'll take a look at some
phased array system toolbox functions
and system objects that can be used to
create a target at a 30 kilometer
distance and 150 meter per second speed
now this another phased array system
toolbox object here that we can use to
create an eight element array so our
data cube will have eight receive
channels now here's our waveform which
is a swept FM pulse with a ten percent
duty cycle you can see the sample rate
for this waveform is one mega Hertz and
the PRF is one kilohertz this means
there will be a thousand samples per
radar pulse this will make up the time
dimension of our radar data cube I'll
run this piece of code and you'll see it
takes about 40 lines of code what we've
created are the MATLAB objects which can
be seen in MATLAB workspace window over
here these are the objects we'll use to
simulate and generate our radar data
cube now the actual generation of the
radar data cube only takes about 15
lines of code you can see it in the
simulation loop here that there are the
32 pulses this is the size of the loop
shown right here now this loop generates
the radar pulse and updates the target
position and propagates the pulse we
generated and reflects off the target
and propagates back to the radar now all
of these returns are collected they're
actually collected right here and the
radar data cube can be assembled at this
point when I run this piece of code I
produce my radar data cube we can see
over here that the dimension of the
radar data cube is here and there are
complex IQ samples that are collected at
the array and the dimensions are a
thousand time samples by eight receive
elements by 32 pulses this is a plot of
a signal receive for one data Channel
for the entire 32 pulse duration now you
might think that the first simulation
was a small data cube so let's increase
the complexity a little bit this next
example instead of having one target
we're
I have 20 targets with random positions
in velocity I receive array will be 121
elements mounted on the surface of a
sphere also we've increased our
bandwidth of the waveform from 1
megahertz the 20 megahertz to give us
additional resolution now the
initialization is a few more lines of
code than in our previous example you
can see the array geometry that we have
in this plot here you can also see the
loop to build this data cube is
identical down to the previous example
the only difference is that the values
that we pass in for the RCS and the
positions are vectors instead of just a
single value for a single target well go
ahead and execute this code to generate
our new data cube we can see the
dimensions of the new data cube 20,000
time samples across 121 receive elements
and 32 pulses now the dimensions have
grown but it's still easy to generate
now if you're interested in how we can
process a radar data cube to determine
the range speed and bearing from this
data cube please watch part 2 of this
recording titled processing the radar
data cube you can find this on our
website at the phased array system
toolbox product page thank you very much
for your time
you