the multi-channel parallel FIR(fast infrared) data communication needs several codecs.With the CPLD(complicated programmable logic device) they can be realized on only one chip.It avails to reduce devices of the telemetry system and simplify setting on the rotor.In this paper
a Codec for FIR data communication was designed with one CPLD chip.The data communication with 4PPM(four pulse position modulation) was tested at 4 Mbps.The reason of mistakes in the communication with 4PPM was found after analyzing the response time of the infrared transceiver and the precision of the oscillation.Then two more efficient codes
2/3PPM and 4/5PPM
were proposed
which enhanced the speed of the data communication.