QPSK implementation in Simulink

Jan 21, 2024#数字通信132

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This is a technical document discussing the overall framework and various modules of a digital communication system. It includes information about modulation, demodulation, and the parameters of different modules. The document also mentions the power spectral density of a QPSK signal and the effects of an AWGN channel. Additionally, it discusses the alignment of the initial signal and the demodulated output in an oscilloscope.

Modulation Section#

Overall Framework#

Parameters of Each Module#

Raised cosine roll-off factor is 1
image.png|500
Single and double polarity transformation

Waveforms of Each Stage#

Buffer#

Demux#

Raised Cosine Transmit Filter#

QPSK Signal Power Spectral Density#

Demodulation Section#

After passing through AWGN channel, assuming carrier synchronization has been performed

Parameters of Some Modules#

Carrier Module#

image.png|475

Pulse Generator#

image.png|500
Due to the serial-to-parallel conversion, the data rate is halved

Some Waveforms#

After the initial signal is delayed for a certain period of time, it is aligned with the demodulated output signal in the oscilloscope, and it can be found that QPSK modulation and demodulation are basically achieved