Editing Infrared Data Association (section)

===IrPHY===
The mandatory '''IrPHY''' ('''Infrared Physical Layer Specification''') is the physical layer of the IrDA specifications. It comprises optical link definitions, modulation, coding, [[cyclic redundancy check]] (CRC) and the framer. Different data rates use different modulation/coding schemes:

* SIR: 9.6–115.2&nbsp;kbit/s, asynchronous, [[RZI]], UART-like, 3/16 pulse. To save energy, the pulse width is often minimized to 3/16 of a 115.2KBAUD pulse width.
* MIR: 0.576–1.152&nbsp;Mbit/s, [[RZI]], 1/4 pulse, HDLC [[bit stuffing]]
* FIR: 4&nbsp;Mbit/s, 4[[Pulse-position modulation|PPM]]
* VFIR: 16&nbsp;Mbit/s, [[Non-return-to-zero|NRZ]], [[Run-length limited#HHH(1,13)|HHH(1,13)]]
* UFIR: 96&nbsp;Mbit/s, [[NRZI]], [[8b/10b encoding|8b/10b]]
* GigaIR: 512&nbsp;Mbit/s – 1&nbsp;Gbit/s, [[NRZI]], [[Amplitude-shift keying|2-ASK]], [[Amplitude-shift keying|4-ASK]], [[8b/10b encoding|8b/10b]]

Further characteristics are:

* Range:
** standard: 2&nbsp;m;
** low-power to low-power: 0.2&nbsp;m;
** standard to low-power: 0.3&nbsp;m.
** The 10 GigaIR also define new usage models that supports higher link distances up to several meters.
* Angle: minimum cone ±15°
* Speed: 2.4&nbsp;kbit/s to 1&nbsp;Gbit/s
* Modulation: [[baseband]], no carrier
* Infrared window (part of the device body transparent to infrared light beam)
* Wavelength: 850–900&nbsp;nm

The frame size depends on the data rate mostly and varies between 64&nbsp;[[byte|B]] and 64&nbsp;kB. Additionally, bigger blocks of data can be transferred by sending multiple frames consecutively. This can be adjusted with a parameter called "window size" (1–127). Finally, data blocks up to 8&nbsp;MB can be sent at once. Combined with a low bit error rate of generally <{{10^|-9}}, that communication could be very efficient compared to other wireless solutions.

IrDA transceivers communicate with infrared pulses (samples) in a cone that extends at least 15 degrees half angle off center. The IrDA physical specifications require the lower and upper limits of [[irradiance]] such that a signal is visible up to one meter away, but a receiver is not overwhelmed with brightness when a device comes close. In practice, there are some devices on the market that do not reach one meter, while other devices may reach up to several meters. There are also devices that do not tolerate extreme closeness. The typical sweet spot for IrDA communications is from {{convert|5|to|60|cm|abbr=on}} away from a transceiver, in the center of the cone. IrDA [[data communication]]s operate in [[half-duplex]] mode because while transmitting, a device's receiver is blinded by the light of its own transmitter, and thus [[full-duplex]] communication is not feasible. The two devices that communicate simulate full-duplex communication by quickly turning the link around. The primary device controls the timing of the link, but both sides are bound to certain hard constraints and are encouraged to turn the link around as fast as possible.