Constellation not visisble after DUC?
2 views (last 30 days)
Show older comments
I am trying to simulate a system in Simulink, where i am trying to generate a QPSK modulated waveform (As you can see in the image below)
![Screenshot from 2019-12-25 20-50-07.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/257134/Screenshot%20from%202019-12-25%2020-50-07.png)
I am getting a proper constellation after the Fiilter block (as you can see in the image below)
![Screenshot from 2019-12-25 20-53-08.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/257135/Screenshot%20from%202019-12-25%2020-53-08.png)
But after the DUC unit, i am getting something
![Screenshot from 2019-12-25 21-00-25.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/257136/Screenshot%20from%202019-12-25%2021-00-25.png)
The spectrum i am getting afetr both the stages are shown below
After Root Cosine
![Screenshot from 2019-12-25 21-05-20.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/257137/Screenshot%20from%202019-12-25%2021-05-20.png)
After DUC unit
![Screenshot from 2019-12-25 21-06-08.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/257138/Screenshot%20from%202019-12-25%2021-06-08.png)
In the image below, we can see the DUC block setting
![Screenshot from 2019-12-25 21-10-34.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/257139/Screenshot%20from%202019-12-25%2021-10-34.png)
Please help me to resolve this issue.
Regards
Amol
0 Comments
Answers (1)
Navya Seelam
on 2 Apr 2020
Digital Up-Converter block converts a complex digital baseband signal to a real passband signal. Since the output of DUC block is real you are getting such constellation. You will get the expected QPSK contellation when you down convert the output of DUC.
0 Comments
See Also
Categories
Find more on QPSK in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!