serial infrared (IrDA) (SIR)
In the IrDA layer model, IrDA Serial Infrared(SIR) forms the physical layer and thus corresponds to the physical layer in the OSI reference model.
Optical transmission takes place on the IrDA layer. SIR specifies the data interface with its parameters, coding, etc. The prerequisite for IR transmissions is a line-of-sight connection between the transmitting and receiving devices. The wavelength range is between 850 nm and 900 nm, with a range of 3 m and a maximum radiation angle of 30 degrees. The transmission speed of Serial Infrared (SIR) is between 9.6 kbit/s and 115.2 kbit/s.
The SIR data packet consists of a start bit, 8 data bits and a stop bit. The header has no parity bit. The cyclic block check(CRC) operates with 16 bits.