A NICAM system includes a NICAM deframer, a FIFO buffer and a symbol rate conversion (SRC) unit. The NICAM deframer obtains multiple deinterleaved symbols according to a strobe signal and a data signal in each timing and expands the deinterleaved symbols to corresponding multiple pulse code modulation (PCM) symbols. The FIFO buffer temporarily stores the symbols and outputs the PCM symbols at a local timing, rate. The SRC unit determines whether a SRC function is enabled according to the statuses of the symbols in the FIFO buffer every a constant time interval. When the SRC function is enabled, the SRC unit interpolates the PCM symbols to obtain multiple new PCM symbols and outputs the new PCM symbols at the local timing rate.