Hi, I'm [INAUDIBLE], an engineer with National Instruments.
In this video, we're showing how you can configure
phase coherent measurement and generation
systems using PXI Vector Signal Transceiver and LabVIEW.
In the hardware setup, we have two PXI Vector Signal
Transceivers, which are both capable of generating
and analyzing one gigahertz of real time bandwidth.
We perform the phase coherent and measurement and generation
in two steps, starting with the alignment of the analyzers
first.
In the first step, here's what the hardware connections
look like.
We're generating an RF signal from one of the two VSTs
and then feeding that into a splitter, which
splits the signal into two signals
and then feeds it into the RF end of each of the Vector
Signal Transceivers.
Also, we'd like to make sure that the local oscillators have
been shared between the generators and the analyzers
of both of the VSTs.
Now let's take a look at the LabVIEW based example
for phase coherent measurement and generation systems.
The first thing that you'd like to do
is to configure the devices and make
sure you have the right frequency, reference level,
and the initial phase offset.
Then once you've made sure that you
have the right configuration settings and both of the VSTs,
click Run.
As you can see in the example here,
we have an average phase difference
of almost 51 degrees.
Because we've already made sure that the generation is
from a single generator and they're using equal length
cables, we can say for sure that this phase difference
is because of the mismatch of phase in the analyzers.
So we'd like to align the analyzers.
For that, click on this button.
It gives you a prompt of the hardware
connection which we've already made.
So close that.
Now once you've done that, what happens
is we're using the average phase difference in the previous case
as an initial phase offset for one of the VSTs.
And therefore, you see that the phase difference
between the two analyzers is now zero degrees, which
means that the analyzers have been aligned.
Now that you have your aligned analyzers,
you have a phase coherent measurement system.
The next step is to align the generators.
To do that, we'd have to change the hardware connections.
So for the next step, which is alignment
of the generators for phase coherent generation system,
we've connected the RF out to RF in for both the VSTs.
As far as the local oscillator connection is concerned,
it's the same as before.
We've shared the local oscillator
between the generators and the analyzers of the two VSTs.
Now let's take a look at the LabVIEW based example.
As you can see here, we have a phase difference
between the two signals.
And it's around minus 23 degrees.
We've already made sure that our analyzers are aligned.
We're also using equal length cables for the RF out
and RF in connection of the two VSTs.
So we can a certain from that this phase difference is
because of the mismatch of phase between the two generators.
To align the phase between the two generators,
we click on align generators, a prompt comes up,
it shows us the hardware connections
that need to be made.
We've already done that.
So let's close this.
And now what happens is we're using the average phase
difference in the previous step as an initial phase offset
for one of the two VSTs.
And that's how we get a zero phase difference
between the two signals.
Now both our generators and analyzers are aligned.
And we have a phase coherent measurement
and generation system.
So that's how we showed how you can configure
phase coherent measurement and generation
systems using PXI Vector Signal Transceiver and LabVIEW.
To learn more about an event or a signal transceiver,
log on ni.com/vst.