This video is part two of a two-part video series on near-field communication device
testing, or more commonly called NFC, using a Keysight InfiniiVision X-Series oscilloscope.
Now, part one, if you haven’t seen it yet, focused on doing or triggering on NFC signals
using the scope and then doing manual parametric measurements.
This video, part two, is focused on automated testing.
Now, the complete automated test system, first of all, consists of an InfiniiVision X-Series oscilloscope,
either the 3000T or the 4000A.
I have here the 4000A.
The 3000T can perform the same exact measurements, but it has a smaller display.
It also includes an arbitrary waveform generator, either the 33500 or 33600 Trueform Waveform Generator
And then another key component is a 3-in-1 programmable NFC antenna.
Now what I mean by 3-in-1 is it has three coils in it.
It has a Listener, size-three equivalent coil, a Poller size-three equivalent coil, and a
calibration coil that we use for resonant frequency.
And then we also have three different versions of this 3-in-1 antenna.
This particular one has a 5 mm spacing between the test plane and the Listener and Poller
coils.
We also have a 10 mm version and a 15 mm version.
And then we have an option where you can get all three.
Now, you should also see on your screen what this antenna actually looks like.
I have it encased inside of a fixture that I had custom made.
But you can see on your screen what this antenna looks like.
The last component of this test system is the NFC option that’s licensed on the scope
and also enables and includes the automated test software that will be running on a PC.
And I have the monitor here.
Now what I’m going to be testing today is a mobile phone that supports most of the NFC
types.
So let’s go ahead and get started and set up the software.
First of all, I’m going to place the phone down on the antenna.
I already have the software app launched.
This is the default screen that comes up, the setup.
This is where we can establish – first of all, select which type of antenna we’re
using, as well as establish our IO connections.
So there’s three different type of antennas we can use.
I mentioned earlier the Keysight 3-in-1.
There’s also the TCI-II, which stands for Test Coil Interface II.
It is a Poller and Listener size equivalent.
It doesn’t include the resonant frequency coil.
And then we also support the standalone NFC reference antennas of any size.
So I’m going to go back and select the Keysight 3-in-1 antennas.
And now let’s make our connections.
I’m going to select Connect.
And it uses Keysight’s IO libraries.
And I’m going to connect to the oscilloscope via USB.
We also support LAN connections.
Next connect to the arbitrary waveform generator.
This takes a little bit longer the first time you launch it because the app has to download
eight different arbitrary waveforms.
And now let’s select to the 3-in-1 antenna.
Let’s just progress from left to right.
We’ll go to this Select Test menu.
This is where we can select which specific test we want to run.
Now you notice it says “Device Active,” “Screen Off,” and “Device Off.”
That simply means if you’re testing a mobile phone, is the mobile phone on and the screen
on?
That means Device Active.
Or the screen could be turned off but the mobile phone on.
And then Device Off means it’s all the way powered down, which supports Listener mode.
So we’re going to use Device Active.
And let’s see what our Poller selections are.
We can test NFC-A, B, F212, and F242.
We can expand each of these and select individual tests.
We’re going to go ahead and select all of the NFC-A Poller tests.
Similar set of tests for NFC-B.
We’ll select all of those.
For now, we’re going to skip NFC-F.
We're going to come back to that.
And let’s see what is available for Listener.
Again: NFC-A, B, F212, F424.
We can expand those.
The primary tests that it performs are frame delay time, load modulation, amplitude, and
response data.
Let’s select all of those.
And also NFC-B: all of those.
Now if I was really concerned about throughput, I would probably turn off screen capture.
Because that slows it down a little bit.
But we’ll go ahead and do a screen capture for all of these.
Let’s move to the Configure menu.
Typically, you can use all the default settings in the Configure menu.
It just customized some of the test parameters, or the way the generator is testing.
The one thing I’m going to change is I’m going to have it leave the arbitrary waveform
generator turned on at the completion of the test.
And you’ll see why later.
Let’s move to the Connect menu.
This gives you a diagram and simply just shows you how all the cables should be connected
between the antenna, the scope, the generator.
I’ve already got all these connected.
So I’m going to click here: Connection Confirmed.
I could click Run Test right here, but I’m going to go ahead and go into the Run menu
to show you my various options.
The default is to run the test that I have selected one time.
I could run it N times.
Or I could run it forever.
And then I could say, “In case of a failure, stop.”
Or “In case of margin certain percent, stop.”
Or I could say, “Pause” or “Continue.”
And there’s a couple other selections.
You can have it send you an e-mail at the end of the test.
We’re going to go back and just run the test one time.
Now I’m going to click Run.
Now on the PC screen here we can see we’re going to run 36 different tests.
We can see the tests running over here on the scope.
This is the Poller NFC-A test.
This is transferring the screen image.
Now it’s going to go to the Poller NFC-B test.
The blue waveform you see here is the rectified voltage.
Now we’ll progress to the Listener NFC-A test.
There’s the sense request and the response.
And then the last test will be the Listener NFC-B. Again: the sense request and the response.
So there the test is completed.
If I had selected all of the tests, which is I think 54 different parameters, and I
chose not to transfer screen images, the total test time is about 45 seconds.
So about 8 seconds per major NFC type for Poller; same for Listener.
So let’s take a look at the test results on this screen here.
Go ahead and slide up to the top.
You can see some of the various parameters we measured.
These are the tests.
Green check mark means it passed.
It’d be a red X if it failed.
“I” means this is just for information only; it doesn’t compare to any specifications.
This column here is the actual value that it measured.
So for the rectified voltage, we measured 1.35 V. The carrier frequency: 13.5602 MHz.
The next column is the margin of passing.
Yellow means marginal; red means fail.
Now, we didn’t get any failures, but I’m going to show you some failures in just a
minute.
And then these are the specifications down here.
Now, if we scroll down to the bottom screen capture – go ahead and re-scale this – there
you can see the screen capture, the very last one.
This was the NFC-B Listener.
So let’s go ahead and select some different tests now.
Let’s turn off the NFC-A and B Poller test, and let’s run a test on NFC-F. Go ahead
and expand, show you which parameters it’s going to be testing.
And let’s not run a test on Listener A and B again.
But let’s do one on Listener F212.
Now the reason I’m running these tests: I want to show you what a failure looks like.
Because my phone typically fails the Listener F212.
And I’ll show you how you can use it as a debugging tool.
So let’s go ahead and click Run.
So the first test here is the Poller NFC-F212 kbits per second.
This looks like pretty good quality there on the SDD request.
And this is the Listener NFC-F212.
At this point, you can’t find the response.
And it’s continuing.
It will do it up to ten times.
Now you can change that parameter in the Configuration menu.
Now when it finishes here, we’ll go in and take a look at this response and I’ll show
you why it couldn’t find it.
So let’s go to the results.
Slide down to the bottom to see that last set.
And you can see down here: the Listener NFC-F failed because it simply couldn’t find the
response.
Now let’s take a look at the scope over here.
And I’m going to open up the zoom window.
This is the sense request sent from our antenna.
Let’s go out and look at the response from the device under test.
And zoom in on the response.
So here you can see: it’s supposed to look like a digital train of pulses.
This does not look like a digital train of pulses to me.
I’m going to turn the zoom off, turn my cursors off, press Run.
Now another thing interesting about NFC-F, both 212 and 424, is here we have the sense
request.
And there are five different time slots where the response can occur.
Now if we want to debug this a little bit, we need to lock in on one particular time
slot.
Now I can do that with a special trigger mode in this scope.
First of all, let me show you what it is triggering on.
It’s triggering on the sense request of NFC-F, which is this point right back here.
I’m going to just press Stop.
And if I turn the trace intensity up a little bit, you can see that there’s some overshoot
on the response.
I can use our zone trigger capability on channel four.
I’m going to draw a zone box right in there and say “Must intersect.”
Then press Run.
Now I’ve locked in on the response only during that time slot.
Let’s now zoom in and take a closer look at our waveforms.
I’m going to scale this down a little bit.
This is what our modulation looks like.
Now, as I showed in the video part one, I showed how to demodulate it.
I’ll repeat it here.
I’m going to go into a waveform math function, turn on the Envelope math function on channel
four.
This performs a Hilbert transform.
Now, it looks a little bit noisy.
I can also filter it just like a normal receiver would do.
And there’s two different ways I could filter.
One is with a smoothing filter, which I showed in video number one.
Or I could use a low pass filter.
Let’s use that one this time.
And we’ll set up a bandwidth of about 5 MHz.
And then I’ll get a nice, clean response.
Now, the scaling is different here.
But you can see it expanded.
So what are the high and low levels of this response?
What is the load modulation amplitude?
The software couldn’t figure it out, and looking at this waveform, I couldn’t figure
it out.
If I was in manufacturing and these are the test results I got, I would send this back
to R&D.
If I was an R&D engineer, I would tune this a whole lot more before I sent this off to
production.
So the last test we’re going to perform is a resonant frequency test.
First of all, I need to turn NFC off on my mobile phone.
Let’s go back to Select Test.
And let’s turn off the NFC-F Poller and Listener test.
And let’s select to perform a resonant frequency test.
Now press Run.
Now it’s probably going to throw me back into the connection diagram and it’s going
to tell me that I need to turn the device off.
Or I could just simply turn NFC off, which is what I’ve done on my phone.
So I’ve got to acknowledge that I read that.
So I’m going to click Run to run the resonant frequency.
The generator sweeps from 10 MHz up to 20 MHz.
And we measure the return loss where the highest return loss here is where the resonant frequency
is.
And you can see on this particular test: we measured 13.9628 MHz.
The last thing I’d like to show you is how you can recall a previously store project.
And with that I can show a complete test with multiple test runs.
So I’m going to open a project that I stored last week and then go into our HTML report,
which is the only thing I haven’t shown you yet.
And there, if I scroll down, you see another summary table.
I was testing the same device, so it failed the Listener NFC-F.
But down here you can see where you can do multiple test runs either on the same device
or on multiple devices.
And you can accumulate statistics of your test data, of min, max, standard deviation.
This is a quite long test report.
I’m not going to go through every detail.
As you’ve seen in this video today, this tool from Keysight doing automated testing:
it could be used in manufacturing tests for qualifying products before you ship them.
Or it could be used in R&D for automated characterization as well as pre-compliance.
And as I also showed, it can be an interactive tool doing automated testing and debugging.
If you haven’t seen video part number one, I encourage you to watch that.
And for more information on NFC testing using oscilloscope, go to the URL on your screen.
Thanks for watching.