Hi, I'm Raj Sodhi, marketing engineer for Keysight Technology's High Performance Signal
Analyzer. I'm excited to show you our new 1 GHz analysis bandwidth solution integrated
in our UXA signal analyzer. A radar engineer can now capture a wider spectrum of the electronic
battlefield, enabling more accurate pulse characterization and radar system interaction
measurements. Engineering is all about connecting ideas and solving problems. This experience
drives the X-Series signal analyzers, the benchmark for accessible performance that
puts you closer to the answer by easily linking cause and effect.
Over the past 50 years, analyzers have evolved from the swept tuned spectrum analyzers of
the '60s to vector signal analyzers of the '90s, to real-time spectrum analyzers with
every-wider bandwidth. With the arrival of 802.11ac, it became necessary to run tests
at 160 MHz bandwidth about an RF carrier. DOCSIS 3.1 pushed this envelope even further.
In aerospace defense, there is an ever-increasing need for analyzing significantly wider bandwidths.
Shown here is a 1 GHz-wide chirp centered at 10 GHz. In the past, we met this requirement
using a two-box solution and the 89600 VSA software. Let me show you how we can do this
using the one-box UXA.
In setting up a realistic signal, I will use the multi-emitter scenario generation software
in combination with the UXG agile signal generator. Using two emitters from a common platform,
it's straightforward to set up interleaved pulses where one pulse has a stepped frequency
from -100 MHz to 100 MHz, and the other is a chirped FM signal ranging from -400 MHz
to +400 MHz. Looking at our signal in swept mode, we see lots of spectral content covering
the middle 800 MHz of our span. Switching over to the real-time spectrum analyzer, we
get a closer look at what's going on.
Here we see the stepped frequencies of the first emitter, ranging from -100 MHz to +100
MHz. We also see the enormous FM chirp in the background spanning 800 MHz, filling up
the entire viewable span of 500 MHz. We may view the signal in a power versus time graph.
We also see a spectrogram or waterfall plot along the left and a spectrum plot along the
bottom. These are all being updated in real time. You may immediately notice two things:
the span has been reduced to 255 MHz, and the pulses are not stable versus time.
For power versus time, the maximum span is 255 MHz, which might explain the funny nature
of that taller pulse. Don't forget we are looking at a chirped signal that is being
chirped across 800 MHz, so we are seeing fragments when the signal goes in and out of our viewing
bandwidth. We may stabilize the power versus time graph by switching the trigger from free
run to level trigger, and then set the trigger level to a salient power, like -5 dBm. Alternatively,
we may leave the trigger level to a lower power, like -30 dBm, and take advantage of
time-qualified triggering. This enables us to trigger when the power versus time has
met certain criteria.
Since we know the first pulse is 10 microseconds wide, we will trigger when the power exceeds
the power threshold for more than 7.5 microseconds and less than 15 microseconds. As you can
see, this also works very well. Let's analyze these pulses using the pulse measurement application.
Using the level trigger, we are able to stabilize these pulses in the time domain. Here we show
amplitude versus time, a table of relevant figures of merit, instantaneous frequency
deviation versus time, and instantaneous phase versus time. All of these are updated in real-time.
Numerous other quantities may be selected for plotting or for tabulation in a pulse
table.
Note that the slope of FM deviation is correct: 40 MHz per microsecond. And if you consider
that the pulse width is 20 microseconds, the chirp will eventually span 800 MHz. But also
notice that the peak-to-peak deviation is only represented as 382 MHz. Clearly with
only 510 MHz, we don't have the bandwidth we need. The chirp signal is going in and
out of our analysis bandwidth. Using the UXA with 1GHz analysis bandwidth in combination
with the 89600 VSA software, we are able to view and analyze the entire signal spectrum.
The left-most graph shows pulse envelope amplitude versus time. We observe a 10 dB difference
in amplitude between the interleaved pulses, and we expected this. We also see amplitude
variation across the wide band chirp. This is further blown up in the right-most graph
as we measure the properties of a single chirp.
Overlaid here is our familiar linear frequency deviation as well as parabolic instantaneous
phase. The middle graph shows the full spectrum of our 1 GHz analysis solution. Here we can
see the stepped frequencies of the first emitter, as well as the enormous bandwidth of the second
emitter. Note that we are only tabulating the figures of merit associated with the chirp
signal. We may economically represent this train of pulses using pulsed descriptor words,
or PDWs for short. The result is a CSV file that may be imported to a UXG agile signal
generator.
In this video, we set up a very wide-band pulsed radar scenario and then analyzed it
with the UXA's integrated 1 GHz bandwidth. This works well with the pulse measurement
application and the 89600 VSA software. With the UXA, you have the highest performance,
widest bandwidth analyzer on the market today that lets you see the real performance of
your device, reducing the cost and hassle of using large, complicated test systems.
Let me invite you to see more and take your designs farther with the X-Series UXA signal
analyzer, now with an integrated 1 GHz bandwidth. Please contact your Keysight sales representative
for more details or even for a live demonstration. Thanks so much.