This article introduces a digital private network of mobile communication dedicated chipset CMX7141 that used for the 4FSK modulation and demodulation in DCR system, and introduces the application of CMX7141 inthe DCR system. Focus research on the channel codec techniques of the chip and have a simulation on the channel coding and decoding. The simulation results indicate that, through channel error correction technique in CMX7141, the BER of DCR system reduces greatly and the transmission quality of DCR system is improved.