256 QAM

[Ginrei]

Hello, 

I have downloaded simulated QAM Modulation of an ASCII String and I'd like to know why constellation plot for 256-QAM does not display correctly. Note that I'm totally new to LabView, but we are suppose to analyze and possibly understand how this .vi works for school project 

Thank you for your help

256QAM

 

[JÞB]

What looks wrong to you?  Why? That would be a start of understanding your coursework.  

I know what the VI is doing and I see nothing wrong with the output.  We have a difference in understanding.

[Ginrei]

Well maybe I'm not understading it right. I thought that the dots in constellation plot were suppose to look more arranged. Like this:

128QAM

[Yamaeda]

I'd expect each ASCII value to correspond to 1 QAM, thus the spread should mimic the text.

/Y

[Ginrei]

So if I'm understanding it right. One ASCII character is 8 bits and 256QAM can code up to 8 bits into one symbol meaning that if I have text of 256 ASCII characters then it should display all 256 dots?

[Yamaeda · Accepted solution]

No, 'A' has ASCII 32, meaning 1 QAM combination, i'm assuming 'AAAA' would repeat the same QAM 4 times.

If you send all ASCII characters you'll have all dots. (given that i'm guessing some on how QAM works)

/Y

[Ginrei]

You are right. I tried to add some other ASCII characters and it started to display more dots. Thank you, sir!

[dorijuin]

Can you share this example to me? I need this for my project.