imum field detection level 1.5 A/m rms Minimum un-modulated field strength 7.5 A/m rms Maximum un-modulated field strength Wireless PAN Standards Table 10-18: ECMA 340 Active Mode Modulation and Bit Coding Methods Bit rate Modulation Bit coding method method 106 kbps ASK (100% Pulse position coding (Modified Miller) - modulation) pulse transmitted at the centre of a bit period for each 1-bit, or at the start of a bit period for an opening 0-bit or a repeated 0-bit. 212/424 kbps ASK (8-30% Manchester coding - transition at the centre modulation) of each bit period; low to high for a 0-bit, high to low for a 1-bit. Reverse polarity (i.e. high to low for a 0-bit, low to high for a 1-bit) is also allowed. Section "Load Modulation, p. 127", entails modulating the load in the target device that the initiating RF field is applied to. This generates sidebands on the original carrier frequency (13.56 MHz) that are detected by the Initiator. Protocol Stack Since NFC is not attempting to provide the full range of network features captured in the OSI model, the protocol stack is very limited and consists of a single simple transport protocol, which defines activation, data exchange and deactivation on an NFC link. The vestiges of a Data Link layer are also evident in the form of media access control based on CSMA/CA. An Initiator checks for an existing Table 10-19: ECMA 340 Passive Mode Modulation and Bit Coding Methods Bit rate Modulation Subcarrier Bit coding method method frequency 106 kbps f/16 = 847.5 kHz Subcarrier modulated using modulation Manchester coding. Reverse polarity not allowed. 212/424 kbps Carrier modulated using modulation Manchester coding. Reverse polarity allowed. Chapter Ten RF field before commencing communication and similarly a Target device in active mode checks for an existing RF field before responding. A single initiating device can interact with multiple targets, each of which generates a random 40 bit ID at the start of the device selection process. The discovery of target device IDs involves