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11. spread spectrum communications: spread spectrum techniques - DS

rain2u 2009. 1. 10. 23:32

11.4.1 direct sequence (DS) modulation

mathematical expression of signal 
  • modulating signal,
     its complex envelope

DS modulation is usually used with BPSK information signals, which have the complex form,


where
 is a binary-valued data waveform of


  • spreading signal,
     its complex envelope,



  • spread spectrum signal, DS/BPSK
DS/BPSK signal is formed by multiplying the BPSK signal by
, resulting in the real transmitted signal

 

DS system block diagram