Brief analysis digital signal carrier transmission
Ling Zhu
0501 Electronic information
Abstract: In the digital communication, the valid available unit frequency intelligence transmission speed [(b/s)/Hz] weighs.The reliability harms the bit rate measure commonly used.Uses the matched filter to be possible to realize the best receive, namely achieved lowest harms the bit rate.In order to enhance the frequency spectrum the use factor, then may use the multiple system numeral modulation: MASK, MFSK, MPSK and MQAM and so on. At present applies most widespread is MPSK and MQAM.MPSK is expresses many kinds of baseband level with M phase.But along with M increase, to carrier synchronization and demodulation precision request also along with it markup.In MDPSK uses the difference demodulation, may avoid withdrawing the frequency synchronism the precise carrier, but harms the bit rate performance to have the drop.
Key words: Validity; Digital modulation; Quadrature amplitude modulation