![]() The typical sweet spot for IrDA communications is from 5 to 60 cm (2.0 to 23.6 in) away from a transceiver, in the center of the cone. There are also devices that do not tolerate extreme closeness. In practice, there are some devices on the market that do not reach one meter, while other devices may reach up to several meters. 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. IrDA transceivers communicate with infrared pulses (samples) in a cone that extends at least 15 degrees half angle off center. Combined with a low bit error rate of generally <10 −9, that communication could be very efficient compared to other wireless solutions. Finally, data blocks up to 8 MB can be sent at once. This can be adjusted with a parameter called "window size" (1–127). Additionally, bigger blocks of data can be transferred by sending multiple frames consecutively. The frame size depends on the data rate mostly and varies between 64 B and 64 kB. Infrared window (part of the device body transparent to infrared light beam).The 10 GigaIR also define new usage models that supports higher link distances up to several meters.To save energy, the pulse width is often minimized to 3/16 of a 115.2KBAUD pulse width. Different data rates use different modulation/coding schemes: It comprises optical link definitions, modulation, coding, cyclic redundancy check (CRC) and the framer. The mandatory IrPHY ( Infrared Physical Layer Specification) is the physical layer of the IrDA specifications.
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