R&S®FS-K112PC
NFC Measurement Software
User Manual
(;ÙÏÜ2)
1175.6578.02 ─ 02
User Manual
Test & Measurement
This manual contains the documentation for the following products.
●
R&S®FS-K112PC (1310.0448.02)
●
R&S®FSPC (1310.0002.03)
The contents correspond to software version 1.1 and higher.
The firmware of the instrument makes use of several valuable open source software packages. For information, see the "Open Source
Acknowledgement" on the user documentation CD-ROM (included in delivery).
Rohde & Schwarz would like to thank the open source community for their valuable contribution to embedded computing.
© 2013 Rohde & Schwarz GmbH & Co. KG
Mühldorfstr. 15, 81671 München, Germany
Phone: +49 89 41 29 - 0
Fax: +49 89 41 29 12 164
E-mail: info@rohde-schwarz.com
Internet: www.rohde-schwarz.com
Printed in Germany – Subject to change – Data without tolerance limits is not binding.
R&S® is a registered trademark of Rohde & Schwarz GmbH & Co. KG.
Trade names are trademarks of the owners.
The following abbreviations are used throughout this manual: R&S®FS-K112PC is abbreviated as R&S FS-K112PC.
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Technical support – where and when you need it
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Centers. A team of highly qualified engineers provides telephone support and will work with you to find a
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1171.0200.22-06.00
Quality management
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1171.0200.11 V 05.01
1171020011
R&S®FS-K112PC
1 Preface....................................................................................................5
1.1 Documentation Overview.............................................................................................5
1.2 Conventions Used in the Documentation...................................................................5
2 Welcome to the NFC Measurement Software......................................7
2.1
2.2 Using the Smart Card Reader......................................................................................8
2.3
2.4 Customizing the User Interface.................................................................................15
2.5 Connecting Measurement Equipment.......................................................................16
3 Measurements and Result Displays...................................................20
Contents
Contents
Installing R&S FS-K112PC...........................................................................................7
Starting the R&S FS-K112PC.....................................................................................11
3.1 Graphical Results........................................................................................................20
3.2 Numerical Results.......................................................................................................28
4 Configuration........................................................................................42
4.1 Managing Measurement Configurations...................................................................42
4.2 Selecting the NFC Modulation Type..........................................................................43
4.3 Selecting a Particular Burst.......................................................................................44
4.4 Configuring the Measurement Equipment................................................................45
4.5 Triggering Measurements..........................................................................................48
4.6 Defining Diagram Properties......................................................................................50
5 Analysis................................................................................................52
6 Remote Control Commands................................................................54
6.1 Introduction.................................................................................................................54
6.2 Common Commands..................................................................................................58
6.3 Measurement Control.................................................................................................59
6.4 General Commands....................................................................................................59
6.5 Result Overview..........................................................................................................62
6.6 Querying NFC-A Poller Results.................................................................................65
6.7 Querying NFC-B and -F Poller Results.....................................................................72
6.8 Querying NFC-A Listener Results.............................................................................75
6.9 Querying NFC-B and -F Listener Results.................................................................79
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6.10 Configuring Listener Characteristics........................................................................80
6.11 Signal Decoding..........................................................................................................80
6.12 Instrument Configuration...........................................................................................82
6.13 Trigger Configuration.................................................................................................86
6.14 Result Display Configuration.....................................................................................89
Contents
Glossary: NFC Terms..........................................................................91
List of Commands................................................................................93
Index......................................................................................................96
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1 Preface
Preface
Documentation Overview
1.1 Documentation Overview
The user documentation for the R&S FS-K112PC consists of the following parts:
Documentation CD-ROM with:
●
– User Manual
– Release Notes
– Data sheet and product brochures
User Manual
The user manual is available in PDF format - in printable form - on the Documentation
CD-ROM delivered with the software. In the user manual, all software functions are
described in detail. Furthermore, it provides a complete description of the remote control
commands.
The user manual is also integrated in the software.
► Select the "View Help" menu item from the "Help" menu.
The software opens the user manual.
Release Notes
The release notes describe new and modified functions, eliminated problems, and last
minute changes to the documentation. The corresponding firmware version is indicated
on the title page of the release notes. The most recent release notes are provided on the
internet.
1.2 Conventions Used in the Documentation
Typographical Conventions
The following text markers are used throughout this documentation:
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Preface
Conventions Used in the Documentation
Convention Description
"Graphical user interface elements" All names of graphical user interface elements on the
screen, such as dialog boxes, menus, options, buttons, and softkeys are enclosed by quotation marks.
KEYS Key names are written in capital letters.
File names, commands, program code
Input Input to be entered by the user is displayed in italics.
Links Links that you can click are displayed in blue font.
"References" References to other parts of the documentation are
File names, commands, coding samples and screen
output are distinguished by their font.
enclosed by quotation marks.
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2 Welcome to the NFC Measurement Software
Welcome to the NFC Measurement Software
Installing R&S FS-K112PC
2.1
Installing R&S FS-K112PC
Successful installation of the program requires two steps.
● Installing Required Components
● Installing R&S FS-K112PC
2.1.1 Installing Required Components
The software requires the installation of several components to run properly. All of these
components are delivered with the software package. Thus, you can install them directly
from the CD-ROM prior to installing the software itself.
Required software components
Microsoft .NET Framework 2.0
●
VISA
●
If the required components are already installed on your computer, you can skip this step.
Installing Microsoft .NET Framework 2.0
The R&S FS-K112PC requires the installation of Microsoft .NET Framework 2.0 or later.
Check if .NET Framework is already installed.
1. Navigate to the installation location (usually the CD-ROM drive).
2. Start \Microsoft .NET Framework 2.0\Check for .NET
Installed.exe
The file checks if .NET Framework is installed or not.
3. If not, start \Install\Framework\Microsoft .NET Framework
2.0\dotnetfx.exe and follow the instructions.
Install VISA
It is also necessary to install VISA (Virtual Instrument Software Architecture) to access
instruments connected to the PC via IEEE or LAN bus. It is then possible to remote control
the measurement instrument.
You can use both National Instruments and Agilent VISA.
● The National Instrument VISA driver CD is supplied together with the R&S FSPC.
You can also visit http://www.ni.com/visa to get the latest version for your operating
system if you are licensed to.
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Welcome to the NFC Measurement Software
Using the Smart Card Reader
If you are using an Agilent hardware or need to use the Agilent VISA, visit http://
●
www.agilent.com to get the latest version for your operating system.
2.1.2
2.1.3
Installing R&S FS-K112PC
After installing all required components, you can install the R&S FS-K112PC.
► Start \FS-K112_v1.1.exe
The installer will do the following:
● Install the R&S FS-K112PC software including an uninstall tool
● Create a Windows Start Menu entry (Programs ⇨ R&S NFC Analysis)
Create a shortcut on the desktop (optional)
●
If necessary (the software will specifically ask you to), set the required environment
●
variables.
Start the software via the Windows "Start Menu" entry or the shortcut on the desktop.
Deinstalling R&S FS-K112PC
You can uninstall the software itself via the uninstall tool available in the Windows "Start
Menu" folder or via "Add or Remove Software" in the Windows "Control Panel".
The Framework components have to be uninstalled manually via "Add or Remove Software" in the Windows "Control Panel".
Before uninstalling the components, make sure that no other software uses one of the
components.
The following components and programs have been installed:
Microsoft .NET Framework 2.0
●
R&S Port Mapper
●
● Rohde & Schwarz NFC Analysis (R&S FS-K112PC)
2.2 Using the Smart Card Reader
The software is licensed by a smart card licensing system. This licensing system requires
a smart card to be connected to the PC when you are using the software. The smart card
and dongle are available as separate products.
You can connect the smart card in two ways.
Connect the smart card in SIM format.
●
If you want to connect the smart card in SIM format, use the USB smart card reader
that is included in the delivery of the software.
Connect the smart card in its full format.
●
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Welcome to the NFC Measurement Software
Using the Smart Card Reader
If you want to connect the smart card in full format, an interface compatible to the
card format is required.
The following devices are able to read the smart card in full format.
– smart card reader integrated in a keyboard
– smart card reader integrated in a notebook
– smart card reader integrated in a desktop PC (e.g. OMNIKEY)
– smart card reader connected to the computer via serial bus or USB (e.g. OMNI-
KEY)
– USB reader connected to a LAN-to-USB converter to distribute the license via
the network (e.g DIGI AnaywhereUSB/2)
Licensing support
If you have any difficulties with the licensing system, support is only assured when you
are using the USB smart card reader that is delivered with the smart card.
Using the USB smart card reader
1. Included in the delivery of the software is the smart card in full format and a smart
card reader.
2. Break out the smart card in SIM format.
3. Insert the smart card into the smart card reader.
a) Turn the smart card reader in a way that the OMNIKEY label faces upward.
b) Insert the smart card with the chip face down and the angled corner facing away
from the reader.
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Welcome to the NFC Measurement Software
Using the Smart Card Reader
4. Push the smart card into the reader as far as possible.
The smart card reader is ready for use on any USB interface.
When you connect the reader to the computer, MS Windows automatically installs
the necessary drivers. If not, you can install the drivers manually from the software
CD. The required files are stored in the directory \Install\USB SmartCard
Reader Driver Files. The driver files are named according to the processor
architecure for which they are designed. (OMNIKEY3x21_x86 or
OMNIKEY3x21_x64).
Information on drivers and driver updates are also included in the ReadMe.txt file
in the same directory as the drivers.
Locking the computer
If you have difficulties unlocking the computer while the smart card is connected because
MS Windows tries to get log-in information from the card after you have locked the computer.
You can solve this issue by editing the system registry.
Automatic change
► Run DisableCAD.reg to change the registry entry automatically.
The file is in the same directory as the driver files.
Manual change
1. Open the Windows "Start Menu" and select the "Run" item.
2. Enter regedit into the dialog box to open the system registry.
3. Look for
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\
policies\system.
4. Set the value of DisableCad to 0.
Administration rights
Security policies of your network environment might prevent you from editing the system
registry or installing drivers. Contact your IT administration in that case.
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Welcome to the NFC Measurement Software
Starting the R&S FS-K112PC
2.3
Starting the R&S FS-K112PC
►
Start the R&S FS-K112PC with the desktop icon or select "Programs" ⇨ "R&S NFC
Analysis" in the Windows "Start Menu"
The user interface (GUI) of the software opens.
Software user interface
Basically, the user interface consists of these elements
a menu bar that provides access to the software functionality at the top
●
a toolbar that provides easy access to the most important functions
●
a workspace
●
In the initial state, the R&S FS-K112PC shows the Result Overview, the Decoding results
and the Poller Values. All other result displays are added to the Poller Values result displays as tabs. For more information on available result displays see chapter 3, "Meas-
urements and Result Displays", on page 20.
If you want another layout of the workspace, you can customize its layout. For more
information see chapter 2.4, "Customizing the User Interface", on page 15.
Adding or removing windows from the workspace
The R&S FS-K112PC provides several types of windows.
● Result displays contain the measurement results of the NFC analysis. The R&S FS-
K112PC provides several result displays, each containing a set of related results.
The "Settings" dialog contains functionality to configure the measurement.
●
You can add as many different windows to the workspace as you want, but each type of
window only once.
► Select the "Window" item in the menu bar.
The software opens a dropdown menu to add or remove windows.
To add a window, just select the corresponding entry in the dropdown menu ( ).
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Welcome to the NFC Measurement Software
Starting the R&S
To remove a window, deselect the corresponding entry in the dropdown menu ( )
or close it with the button.
Hidden tabs
If the icon is visible in one of the window frames, there are hidden tabs that don't fit in
the user interface. If you click on the icon, a list of all active tabs in that window opens.
Performing a preset
All settings have been assigned predefined values that you can restore anytime you need.
► Select the "Preset" menu item from the "File" menu.
FS-K112PC
The software restores the predefined values for all settings.
SCPI command:
SYSTem:PRESet on page 61
Running measurements
When you start the software, it assumes that it gets the data from an instrument (spectrum
analyzer or oscilloscope) that is connected to the PC via TCP/IP. In that case, the
R&S FS-K112PC records and evaluates the I/Q data live from the measurement equipment.
Currently, the R&S FS-K112PC supports the following instruments:
● R&S FSL (spectrum analyzer)
● R&S FSV (signal analyzer)
● R&S FSQ (signal analyzer)
● R&S FSW (signal analyzer)
● R&S ZVL (network analyzer)
● R&S RTO (oscilloscope)
►
Press the
measurement.
Note that the button initiates the recording of the I/Q data. Current I/Q data is lost.
The amount of I/Q data depends on the "Capture Length" you have defined. For more
("Run Measurement") and buttons in the toolbar to start or stop a
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Welcome to the NFC Measurement Software
Starting the R&S FS-K112PC
information see chapter 4.4, "Configuring the Measurement Equipment",
on page 45.
SCPI command:
INITiate[:IMMediate] on page 59
►
Press the button to evaluate the I/Q data currently in the capture buffer again.
Refreshing the results is useful if you want to evaluate the I/Q data with different
settings, for example.
SCPI command:
INITiate:REFResh on page 59
As an alternative to a live recording you can restore previously recorded I/Q data from a
file and evaluate that I/Q data again.
Importing signal data
If you have a recorded set of I/Q data stored in a file with the file extension *.iq.tar, you
can load it into the software.
► Select the "Load I/Q Data" menu item from the "File" menu.
The software opens a dialog box to select the file. The file must have the .iq.tar format.
SCPI command:
MMEMory:NFC:LOAD:IQ on page 60
After you have opened the file, the software analyzes the data that the file contains automatically.
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Welcome to the NFC Measurement Software
Starting the R&S
The iq.tar file format
An .iq.tar file contains I/Q data in binary format together with meta information that
describes the nature and the source of data, e.g. the sample rate. The objective of
the .iq.tar file format is to separate I/Q data from the meta information while still having
both inside one file. In addition, the file format allows you to include customized data.
An .iq.tar file must contain the following files.
I/Q parameter .xml file
●
Contains meta information about the I/Q data (e.g. sample rate). The filename can
be defined freely, but there must be only one single I/Q parameter .xml file inside
an .iq.tar file.
I/Q data binary file
●
Contains the binary I/Q data of all channels. There must be only one single I/Q data
binary file inside an .iq.tar file.
Optionally, an .iq.tar file can contain the following file.
I/Q preview .xslt file
●
Contains a stylesheet to display the I/Q parameter .xml file and a preview of the I/Q
data in a web browser.
FS-K112PC
Exporting signal data
When you have recorded I/Q data that you want to have access to later, the R&S FSK112PC allows you to export the I/Q data to a file.
► Select the "Save I/Q Data" menu item from the "File" menu.
The software opens a dialog box to define the name and target folder of the file.
Note that the file extension you have to use is *.iq.tar.
SCPI command:
MMEMory:NFC:STORe:IQ on page 60
When you save the signal to a file you can load and view it again anytime you want (see
"Importing signal data" on page 13).
Exiting the software
► Select the "Exit" menu item from the "File" menu.
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Welcome to the NFC Measurement Software
Customizing the User Interface
2.4 Customizing the User Interface
In addition to adding and removing elements to and from the workspace, you can also
customize the layout of the user interface by docking elements to a particular position of
the working area, by adding a tab to an existing element or by altogether removing an
element from the user interface.
2.4.1 Docking Elements
1. Select an element in the title bar with the mouse and move it around until a docking
spot appears.
Docking spots look like this:
2. Move the mouse cursor over one of the possible docking spots.
The border of the docking spot turns blue. The screen area in which the element will
be positioned also turns blue.
3. Release the element.
The element docks itself to the corresponding area of the GUI.
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Welcome to the NFC Measurement Software
Connecting Measurement Equipment
2.4.2 Adding an Element as a Tab
1. Select an element with the mouse and move it over the center docking spot in an
area where another element already is.
2. Release the element.
The released element is added as a tab to the element.
The active tab always is in a lighter color than the others.
Note that tabs may be at the top of the window or at the bottom of the window,
depending on where the window is in the user interface.
3.
Select the tab you need by either clicking on the tab itself or by clicking on the
symbol and selecting the tab you need from the list.
2.4.3 Removing an Element from the GUI
► Select an element with the mouse, move it around and release it.
If you haven't docked the element or added it as a tab, it is floating around as an
individual window. You can also move the element completely out of the GUI and
work with it in an independent window (e.g. another monitor).
2.5 Connecting Measurement Equipment
In order to be able to communicate with an analyzer or oscilloscope, you have to establish
a connection between the measurement equipment and the computer in a local area
network (LAN).
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Connecting Measurement Equipment
For more information on supported instruments see "Running measurements"
on page 12.
Requirements
To be able to capture signal data, you need one of the instruments mentioned above.
To establish a connection, you also have to determine the network address of the instruments and set it up in the software.
For more information on including the instrument configuration in the software see chap-
ter 4.4, "Configuring the Measurement Equipment", on page 45.
2.5.1 Figuring Out the Address of an R&S FSV
Follow these steps to figure out the network address of an R&S FSV.
1. Press the SETUP key.
2. Press the "General Setup" softkey.
3. Press the "Network Address" softkey.
4. Press the "IP Address" softkey.
The R&S FSV opens a dialog box that contains information about the LAN connection.
2.5.2 Figuring Out the Address of an R&S FSL or R&S ZVL
Follow these steps to figure out the network address of an R&S FSL or R&S ZVL.
1. Press the SETUP key.
2. Press the "General Setup" softkey.
3. Press the "Network Address" softkey.
4. Press the "IP Address" softkey.
The analyzer opens a dialog box that contains information about the LAN connection.
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Welcome to the NFC Measurement Software
Connecting Measurement Equipment
2.5.3 Figuring Out the Address of an R&S FSQ
Follow these steps to figure out GPIB or IP address of an R&S FSQ.
1. Press the SETUP key.
2. Press the "General Setup" softkey.
3. Press the "Configure Network" softkey.
4. Press the "Configure Network" softkey.
The MS Windows "Network Connections" dialog box opens.
5. Select the "Local Area Connection" item.
The "Local Area Connection Status" dialog box opens.
6. Select the "Support" tab.
The "Support" tab shows the current TCP/IP information of the R&S FSQ.
2.5.4 Figuring Out the Address of an R&S FSW
Follow these steps to figure out the GPIB or IP address of an R&S FSW.
1. Press the SETUP key.
2. Press the "Network + Remote" softkey.
The R&S FSW opens the "Network & Remote" dialog box and shows its current IP
address in the corresponding field.
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Welcome to the NFC Measurement Software
Connecting Measurement Equipment
2.5.5 Figuring Out the Address of an R&S RTO
Follow these steps to figure out the network address of an R&S RTO.
► Press the SETUP key.
The R&S RTO opens a dialog box that contains general information about the system.
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3 Measurements and Result Displays
Measurements and Result Displays
Graphical Results
After the R&S FS-K112PC has evaluated the I/Q data, you can display the test results in
various graphical and numerical result displays.
Quick evaluation of test results
Each result display has a colored bar at the top that displays the test results so that you
can see at a quick glance if the test has passed or failed.
The results are highlighted depending on the quality of the signal (and provided that the
software could find an actual NFC signal in the I/Q data).
green highlighting
●
The test has passed. The signal complies to the specifications defined by the NFC
Forum.
yellow highlighting
●
The test has passed in parts. However, something did not comply to the specifications
defined by the NFC Forum (e.g. if the listener has passed the test, but the poller did
not).
red highlighting
●
The test has failed completely. No signal parts comply to the specifications defined
by the NFC Forum or the software was not able to process the data as expected.
no highlighting
●
The R&S FS-K112PC could not detect an NFC signal in the I/Q data.
3.1 Graphical Results
The graphical displays are basically a representation of the signal power against a particular period of time.
► Select the "Capture Buffer", the "Poller PvT Graph" or the "Listener PvT Graph" item
from the "Windows" menu.
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Measurements and Result Displays
Graphical Results
The software opens the corresponding windows and displays the results if you have
previously performed a measurement.
● Capture Buffer.........................................................................................................21
● Poller Characteristics..............................................................................................23
● Listener Characteristics...........................................................................................25
3.1.1 Capture Buffer
The "Capture Buffer" result display shows the power level of the complete I/Q data stored
in the capture buffer. The size of the capture buffer depends on the capture length you
have defined (see chapter 4, "Configuration", on page 42).
Fig. 3-1: Capture buffer containing the I/Q data of an NFC-F signal (based on example file NFC-
F_212kB_Example.iq.tar)
The software calculates and shows the envelope voltage of the signal relative to the level
of the carrier signal transmitted by the poller. The carrier signal is a continuous wave.
The carrier signal is normalized to 100 %. The voltage is displayed on the left diagram
axis.
When two NFC devices exchange data, the carrier signal supplied by the poller is modulated for a particular amount of time (the 'low state transition' in case of poller signals and
'load modulation' in case of listener signals). During this time, the voltage of the carrier
signal drops or rises by a certain amount. You can see the taps into the power by the
shape of the trace.
= carrier signal, power = 100 %
1
2 = low state transition, power = < 10 % of the modulation depth (poller signal)
2 =
load modulation, power ≠ 100 % (listener signal, not shown)
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Measurements and Result Displays
Graphical Results
In order to synchronize to the signal, the software looks for a poller request. A poller
request consists of a set of low state transitions, whose characteristics depend on the
modulation type. A set of low state transitions in that context is also referred to as a burst.
When the software is synchronized to the signal, it tries to analyze and demodulate all
bursts that it finds in the capture buffer (poller and listener communication).
Note that the R&S FS-K112PC only analyzes bursts of one NFC modulation type at a
time. Therefore, it analyzes subsequent bursts only if they are of the same modulation
type as the first detected modulation type (automatic detection) or if they are of the modulation type you have selected manually from the toolbar.
After the analysis of the NFC bursts is done, the software shows the results for each burst
of the same modulation type as a colored bar at the bottom of the diagram.
Green bar
●
Signal areas where an (NFC) signal has been detected and analyzed. The signal
complies to the specifications by the NFC Forum.
Grey bar
●
Signal areas where an (NFC) signal has been detected, but not analyzed because
the signal does not comply to the currently selected modulation type.
Red bar
●
Signal areas where an (NFC) signal has been detected and analyzed. The signal,
however, does not comply to the currently selected modulation type.
However, even if the signal is a valid NFC signal, demodulation might not be possible.
This may be the case if, for example, the selected modulation type does not match the
modulation type of the signal.
The figure below shows the same signal in both diagrams. In the left picture, the signal
has not been evaluated because the selected modulation type does not match the signal
modulation type. The software shows a grey bar. If the selected modulation type matches
that of the signal, the demodulation did work and the signal is marked by a green bar.
Fig. 3-2: NFC-B signal with NFC-A selected (left) and NFC-B selected (right) (based on example file NFC-
B_Example.iq.tar)
The result display also shows the phase oscillation in the diagram as a red line when you
turn on the display of the phase characteristics (see "Phase Shown" on page 51). In
that case, the right vertical diagram axis represents the scale of the phase display.
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Graphical Results
3.1.2 Poller Characteristics
The "Poller PvT" result display shows the level characteristics of the NFC poller over the
period of exactly one low state transition. It also shows if the low state transition is within
the limits defined by the NFC Forum graphically.
Basically, a poller transmission consists of several low state transitions. During a low
state transition, the voltage drops to a lower level than the carrier signal. The number of
low state transitions in the signal depends on the amount of bits that are transmitted.
Fig. 3-3: NFC-A poller signal (based on example file NFC-A_Example.iq.tar)
Viewing all low state transitions
If you want to see all low state transitions of the transmission, use the "Capture Buffer"
result display.
The displayed voltage is the voltage of the signal in % of the carrier signal transmitted by
the poller. The carrier signal is normalized to 100 %.
Note that the result display consists of two panes in case of NFC-B and NFC-F signals.
The left pane shows the falling edge of the low state transition.
●
The right pane shows the rising edge of the low state transition.
●
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Measurements and Result Displays
Graphical Results
Fig. 3-4: NFC-B poller signal (based on example file NFC-B_Example.iq.tar); NFC-F looks similar
Compared to NFC-A, NFC-B and NFC-F do not define limits for the duration of the low
state transition. Limits are only defined for the rising and falling edges. Thus, the scale
of the horizontal axis is variable for these modulation types and the R&S FS-K112PC
only shows the falling and rising edges.
For NFC-A, the limits and duration of the transition are fix. Therefore, the scale of the
horizontal axis is also fix.
The result display contains several lines, distinguished by colors. For a quick assessment
of the contents of the result display, it includes a key to the colors above the diagram.
Red lines
●
The red lines are the upper and lower limits defined by the NFC Forum. If the signal
complies to the specified limits, all RF traces have to be within the two red lines. If
one of the signal traces violates the limits, the RF test fails.
In case of NFC-A signals, the limits not only define the voltage that the signal should
have, but also the duration of the transmission.
Grey lines
●
The grey lines indicate the modulation depth.
The modulation depth is the magnitude of the voltage drop during the low state transition. The modulation depth is a percentage with the carrier signal being 100%.
The modulation index defined for NFC-B and NFC-F also represents the voltage drop
during the low state transitions, but is a ratio of voltages at defined locations of the
transition.
with Va being the high amplitude and Vb being the low amplitude.
Blue, black and green traces
●
The blue, black and green traces show the level characteristics of the poller signal
over time. The displayed time is a little longer than one NFC low state transition lasts.
The different colors represent different evaluation methods.
– The blue trace represents the minimum voltage that has been measured for all
transitions during the transmission.
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Graphical Results
– The light green trace represents the maximum voltage that has been measured
for all transitions during the transmission.
– The black trace represents the average voltage of all transitions during the trans-
mission.
The number of low state transitions included in the evaluation of the minimum, maximum and average voltage depends on the amount of information contained in the
poller request.
Example:
In case of the signal shown below (from the "Capture Buffer" result display), the R&S FS-
K112PC would include seven low state transitions in the evaluation of the minimum,
maximum and average traces.
3.1.3
Fig. 3-5: Several NFC-A low state transitions (based on example file NFC-A_Example.iq.tar)
Listener Characteristics
The "Listener PvT" result display shows the level characteristics (load modulation) of the
NFC listener over the period of the transmission.
The listening device is a passive device that draws its power from the carrier signal that
the NFC poller generates. This passive use of power from an external device is called
load modulation, whose characteristics are the main focus when testing the listening
device.
In case of NFC-A signals, the result display consist of two panes, both showing the load
modulation.
The left pane shows the minimum, maxmimum and average load modulation over
●
eight ASK transitions. Eight transitions correspond to one bit. This number is defined
by the NFC Forum as a quality indicator of the load modulation.
The right pane shows the minimum, maximum and average load modulation over one
●
ASK transition.
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Graphical Results
Fig. 3-6: NFC-A listener signal (based on example file NFC-A_Example.iq.tar)
The displayed results are an indicator of the evenness of the ASK transitions. The
load modulation results are displayed in the unit mV. The zero level is normalized to
the 100 % of the voltage of the carrier signal.
In case of NFC-B, the result display shows one pane. The pane shows the minimum,
maximum and average load modulation over all measured ASK transitions.
Fig. 3-7: NFC-B listener signal (based on example file NFC-B_Example.iq.tar)
In case of NFC-F, the result display shows two panes.
The left pane shows the falling edge of the load modulation.
●
The right pane shows the rising edge of the load modulation.
●
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Fig. 3-8: NFC-B listener signal (based on example file NFC-F_424kB_Example.iq.tar)
The listener RF characteristics contain several traces, distinguished by different colors.
For a quick assessment of the contents of the result display, the result display also contains a key to the colors above the diagram.
Grey lines
●
The grey lines indicate the lower and upper load modulation levels.
Blue, black and green traces
●
The blue, black and green traces show the RF characteristics of the load modulation.
The different colors represent different evaluation methods.
– The blue trace represents the maximum load modulation that occured during the
transmission.
– The light green trace represents the minimum load modulation that occured dur-
ing the transmission.
– The black trace represents the average load modulation that occured during the
transmission.
The number of load modulation cycles included in the evaluation of the minimum, maximum and average voltage depends on the number of transmitted bits.
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Numerical Results
Example:
In case of the signal shown below (from the "Capture Buffer" result display), the software
would include 17 load modulation cycles in the evaluation of the minimum, maximum and
average traces.
Fig. 3-9: Several NFC-F load modulation cycle (based on example file NFC-F_424kB_Example.iq.tar)
3.2 Numerical Results
The numerical results for NFC measurements show various test results in numerical format.
The R&S FS-K112PC features four numerical result displays, containing different information about the complete RF signal, the NFC poller and the NFC listener.
► Select the "Overview", the"Poller Values", the "Listener Values" or the "Decoding"
item from the "Window" menu.
The software opens the corresponding windows and displays the results if already
available.
3.2.1 Result Overview
The result overview contains basic characteristics of the signal that has been analyzed.
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