Abstract：Thearticleismainlydevotedtothetheoryaswellastheachievementonthemodulationanddemodulationofπ/

4-DQPSKsysteminthesoftwareSystemView.Besides，thearticleanalysesthedynamicandstatic

behaviorsoftheπ/4-DQPSKsystemaswellastheperformanceagainstnoiseundertheconditionofGaussnoise

channel.Thecomparisonismadeonthespectrumandanti-noiseperformancebetweenπ/4-DQPSKandQPSK

underthethesamechannel.Theresultofsimulationshowsthatthespectrumexpandingofπ/4-DQPSKissuperiortothatoftheQPSKsystem.

Keywords：π/4-DQPSK；SystemView；computeraideddesign（CAD）；Matlab-Abstract:
Thearticleismainlydevotedtothetheoryaswellastheachievementonthemodulationanddemodulationof
pi/4-DQPSKsysteminthesoftwareSystemView.Besides,
thearticleanalysesthedynamicandstatic behaviorsofthe pi
/4-DQPSKsystemaswellastheperformanceagainstnoiseundertheconditionofGaussnoise

channel.Thecomparisonismadeonthespectrumandanti-noiseperformancebetween
pi /4-DQPSKandQPSK
underthethesamechannel.Theresultofsimulationshowsthatthespectrumexpandingof
pi /4-DQPSKissuperiortothatoftheQPSKsystem. Keywords: Pi /4-DQPSK;
SystemView; Computeraideddesign (CAD); Matlab