NFC Technology and Conformance Testing
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Agenda
l NFC Basicsl Standard Evolutionl Physical Layer Compliance Tests
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NFC Introduction
l Contactless data exchangel Passive – activel Active – active
l Close proximity ~ 10 cml Data transfer using the “near
field”l Low carrier frequency of 13.56 MHzl Magnetic coupling between
transmitter and receiver similar to transformer principle
l Standard developed jointly by NXP and Sony
l Backward compatible with smart card technologyl ISO/IEC 14443 A/Bl JIS X 6319-4
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NFC Coupling Method
Information is coupled between the polling and listening devices using the near field – equivalent to transformer principle
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Frequency Spectrum of NFC Signal
l Auxiliary carriers transfer information from passive listener (target) to poller (initiator) through load modulation on poller antenna
l Auxiliary carriers are not used in peer to peer communicationl Carrier is used as a power source in active-passive communications
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Modulation Types
l Poller (initiator) uses ASK modulation on 13.56 MHz carrier
l Passive devices communicate on auxiliary carrier via load modulationl ASK for 14443A and PSK for 14443Bl ASK directly on carrier for JIS X
6319-4
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Coding Types Used in NFC
l NRZ-L: logical 1 and 0 coded as high and low level and signal level is maintained throughout a bit period
l Manchester: first half bit is high for a logical 1 and second half is high for logical 0
l Modified Miller: negative going pulse after half a bit interval for a 1 and at the start of a bit interval for a 0. For a 1 followed by a zero, no pulse
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Frequency and Time Representation
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Evolution of NFC Air Interface
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NFC Operating Modes
l Card emulation mode (passive mode): behaves like existing contactless card and conforms to one of the legacy standards
l Peer to Peer mode: both devices are active and exchange datal Reader/Writer mode (active mode): the NFC device is active and
reads or writes a passive legacy RFID tag
Each mode canUse any of 3 technologies
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Poll Mode Resolution
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NFC Standards Overview
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NFC Tag Types
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NFC RF Measurements – Listening Device
l NFC Forum Reference Polling Devicel Sends commands to listening devicel Received response from listening device (load modulation)
l Command generator – modulated 13.56 MHz carrierl Load modulation measuring tool – oscilloscope or signal anlyzer
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NFC RF Measurements – Polling Device
l NFC Forum reference listening devicel Receives polling signal from device under testl Transmits appropriate response via load modulation
l Listening device response generator – arbitrary waveform generator (AWG)
l Measuring waveform tool – analyzes the polling signal and generates a trigger for the response generator
l Measuring Field tool – measures the carrier power from the poller
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NFC Reference Polling and Listening Devices
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RF Tests for NFC Devices in Polling Mode
l Carrier frequency accuracyl Power level measurementl Sufficient power to drive passive devicesl Measured within the specified volume above the coupling device
l Waveform characteristicsl Rise time, fall time, etc.
l Load modulation sensitivityl Correct reception at minimum specified level
l Threshold level testl Polling device must switch off its RF field when exposed to an RF field f
a certain strength
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RF Tests for NFC Devices in Listening Mode
l Load modulation measurementl The signal strength of the load modulation must be within required limits
l Power receptionl The listening device must answer correctly even in bad conditions
l Frame delay timel Response time from the end of the polling command to the start of
transmission from the phone in card emulation model Important in NFC-A mode for anti-collision
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Test Setup for Polling Mode
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Test Setup for Listening Mode
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Carrier Power and Frequency Measurement
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Load Modulation
Polling command
Load modulation
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Automated Measurement Software
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Poller Timing Values
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Poller Signal vs. Time
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Listener Values
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Listener Signal vs. Time
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Summary
l NFC technology is an evolution of contactless data exchangel Addition of peer to peer and read/write to passive smart card model Backward compatible with legacy smart card
l The NFC forum has established both RF and protocol compliance tests l Guarantees interoperability
l RF testing verifies the air interface for polling and listening devicesl Reference poller and listener l Command and response generator (AWG and vector signal generator)l Waveform analysis tool (oscilloscope with NFC trigger and I/Q
demodulation)l Automation software controls acquisition and analyzes waveform data
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Contact Us
About Rohde & Schwarz
Rohde & Schwarz is an independent group of companies specializing in electronics. It is a leading supplier of solutions in
the fields of test and measurement, broadcasting, radiomonitoring and radiolocation, as well as secure communications.
Established more than 75 years ago, Rohde & Schwarz has a global presence and a dedicated service network in over 70
countries. Company headquarters are in Munich, Germany.
Europe, Africa, Middle East
+49 89 4129 12345
North America
1-888-TEST-RSA (1-888-837-8772)
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www.rohde-schwarz-scopes.com
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