Near Field Communications (NFC) Technology & Measurements
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La tecnología NFC permite el intercambio de datos sin contacto, utilizando un rango de proximidad de aproximadamente 10 cm y una frecuencia portadora de 13.56 MHz. Incluye modos de emulación de tarjeta, peer-to-peer y lectura/escritura, asegurando la compatibilidad con estándares de tarjetas inteligentes legados. Se establecen pruebas de conformidad y interoperabilidad mediante pruebas RF para verificar la interfaz de aire de los dispositivos de sondeo y escucha.
Near Field Communications (NFC) Technology & Measurements
- 1. NFC Technology and Conformance Testing
- 2. Agenda l NFC Basics l Standard Evolution l Physical Layer Compliance Tests 2
- 3. NFC Introduction l Contactless data exchange l Passive – active l Active – active l Close proximity ~ 10 cm l Data transfer using the “near field” l Low carrier frequency of 13.56 MHz l Magnetic coupling between transmitter and receiver similar to transformer principle l Standard developed jointly by NXP and Sony l Backward compatible with smart card technology l ISO/IEC 14443 A/B l JIS X 6319-4 3
- 4. NFC Coupling Method Information is coupled between the polling and listening devices using the near field – equivalent to transformer principle 4
- 5. 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 communication l Carrier is used as a power source in active-passive communications 5
- 6. Modulation Types l Poller (initiator) uses ASK modulation on 13.56 MHz carrier l Passive devices communicate on auxiliary carrier via load modulation l ASK for 14443A and PSK for 14443B l ASK directly on carrier for JIS X 6319-4 6
- 7. 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 7
- 8. Frequency and Time Representation 8
- 9. Evolution of NFC Air Interface 9
- 10. NFC Operating Modes Each mode can Use any of 3 technologies 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 data l Reader/Writer mode (active mode): the NFC device is active and reads or writes a passive legacy RFID tag 10
- 11. Poll Mode Resolution 11
- 12. NFC Standards Overview 12
- 13. NFC Tag Types 13
- 14. NFC RF Measurements – Listening Device l NFC Forum Reference Polling Device l Sends commands to listening device l Received response from listening device (load modulation) l Command generator – modulated 13.56 MHz carrier l Load modulation measuring tool – oscilloscope or signal anlyzer 14
- 15. NFC RF Measurements – Polling Device l NFC Forum reference listening device l Receives polling signal from device under test l 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 15
- 16. NFC Reference Polling and Listening Devices 16
- 17. RF Tests for NFC Devices in Polling Mode l Carrier frequency accuracy l Power level measurement l Sufficient power to drive passive devices l Measured within the specified volume above the coupling device l Waveform characteristics l Rise time, fall time, etc. l Load modulation sensitivity l Correct reception at minimum specified level l Threshold level test l Polling device must switch off its RF field when exposed to an RF field f a certain strength 17
- 18. RF Tests for NFC Devices in Listening Mode l Load modulation measurement l The signal strength of the load modulation must be within required limits l Power reception l The listening device must answer correctly even in bad conditions l Frame delay time l Response time from the end of the polling command to the start of transmission from the phone in card emulation mode l Important in NFC-A mode for anti-collision 18
- 19. Test Setup for Polling Mode 19
- 20. Test Setup for Listening Mode 20
- 21. Carrier Power and Frequency Measurement 21
- 22. Load Modulation Load modulation Polling command 22
- 24. Poller Timing Values 24
- 25. Poller Signal vs. Time 25
- 26. Listener Values 26
- 27. Listener Signal vs. Time 27
- 28. Summary l NFC technology is an evolution of contactless data exchange l Addition of peer to peer and read/write to passive smart card mode l 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 devices l 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 28
- 29. 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 customersupport@rohde-schwarz.com North America 1-888-TEST-RSA (1-888-837-8772) customer.support@rsa.rohde-schwarz.com Latin America +1-410-910-7988 customersupport.la@rohde-schwarz.com Asia/Pacific +65 65 13 04 88 customersupport.asia@rohde-schwarz.com www.rohde-schwarz-scopes.com 29