Hello, I'm Richard Overdorf and I am an engineer at Agilent, Santa Rosa, where we do R&D for
signal analyzers. Today, we are going to compare the Agilent real-time PXA with the Tektronix
RSA6000 Series and its 110 MHz of bandwidth. This comparison will focus on key performance
parameters, typically influence the ability to identify and measure intermittent or transient
signals. We are also going to look at interference or signals within signals. I am going to highlight
standard attributes that can be verified from each of the instrument's specification guides.
The PXA has exceptional dynamic range; the TOI performance is an indication of how well
the PXA handles large signals. The sensitivity, or DANL, of the PXA is also industry-leading.
We are going to show a couple of examples of why this is important for real-time analysis.
In our instrument setup we have two PSG signal generators we will use to generate two pulses:
one large pulse and one small pulse at X-band. These signals will be very close in frequency
and overlap one another. Finding a small, intermittent pulse in the presence of a larger
pulse is a common use case for radar in electronic warfare. I am going to optimize each instrument
to make this challenging dynamic range measurement. The PXA can measure the signal accurately
with 16 dB of attenuation. Fortunately the PXA has 2 dB step attenuation in RTSA mode
to help find the dynamic range sweet spot. A preamp will not work well here because of
the larger input signal. Next we want to identify a hard-to-find intermittent signal. We are
going to use a splitter and feed the same signal into each instrument. The signal has
a period of 1 second and a duration of 4 µs. In addition, we are going to place the signal
close to the noise floor at a power level of -63 dBm, not including the splitter's attenuation.
The probability of detecting a signal is a function of multiple things. One factor is
how much power the signal of interest has in relationship to a threshold, or in this
case the noise floor. This is why the instrument's raw noise performance becomes important for
detecting intermittent signals. The PXA has approximately 5 dB better noise performance
here. It also has the widest real-time bandwidth and a higher sample rate which also improves
its probability of intercept. The PXA is doing a much better job of catching the signal every
second. The Tek RSA has the ability to go narrow in RBW which improves noise performance.
I am going to lower the RBW to further lower the noise floor. As you can see the RSA is
still not catching the signal as consistently as the PXA. This is because the tradeoff between
a lower RBW is degraded POI. I measured the noise level of the Tek RSA at three specific
RBWs. At these same RBWs I also recorded the POI spec from the RSA's data sheet. I did
the same with the PXA. This graph shows the PXA in RSA's minimum signal duration POI spec
at each noise level. You can see that at a given noise level the PXA can detect shorter
signals than the RSA, or in other words, has a much better POI at a specified noise level.
Another way to look at this is that for a specific signal duration the PXA is able to
measure a lower-level signal. Overall, the PXA does a better job at finding intermittent
signals, primarily because it has a higher sample rate and better noise performance.
Perhaps more important is the fact that the PXA is not only the highest-performing real-time
analyzer but also has the ability to make many must-have measurements such as wide-range
swept spurious or EMI measurements, as well as noise figure and phase noise. In addition,
the PXA offers the performance needed by the more stringent requirements for both radar
and communication systems. From fast sweep times for wider spurious scans, excellent
amplitude accuracy for uncertainty and repeatability to more than 20 dB better phase noise. The
ability to make both standard-based measurements as well as the real-time measurements allow
for the most cost-effective solution for even the highest-performing requirements. In summary,
we have seen how the PXA's superior dynamic range enables it to see small, intermittent
signals in the presence of larger ones. We showed the PXA finding low-level, intermittent
signals with the best probability of intercept available on the market today. Finally, we
reviewed how the PXA can make other must-have measurements needed by most engineers. To
learn more about Agilent's real-time signal analysis please visit the site listed or view
more real-time PXA videos. Thanks for watching.