why we convert data into even and odd parts for qpsk

[abdullah gill]

i m stuck in a basic understanding of qpsk i m working on system generator so to do a qpsk i have to convert the data into even and odd parts but i m unable to find the reason . can someone do me a favour by telling me the solution.
regards

Added after 18 minutes:

we convert them into even and odd parts because odd parts supports the i-channek and even part supports q-channel........but how we do that help me

 

[Communications_Engineer]

if modsym variable has got qpsk symbols, you can separate real and quad signal as real(modsym) and the quad as imag(modsym)

 

[abdullah gill]

i m sorry i cant get u if u can elaborate it a bit more it wll be helpful. thanks

 

[mankeer]

Hi Abdulla,

As u know, each qpsk symbol contains a real part and an imaginary part, so in order to form the real part I need the bits with the odd bits, and to form the imaginary part u need the even bits.

e.g

the qpsk symbols are :

1. 0.707 + 0.707 j
2. -0.707 + 0.707 j
3. -0.707 - 0.707 j
4. 0.707 - 0.707 j

so if bit number 1 is 0 and bit number 2 is 0 then the qpsk symbol will be 0.707 + 0.707 j, while if one of the bits is one u have to change the sign of the 0.707 to be negative.

that's all, I hope u got my point.

 

[abdullah gill]

if i have a data like 4210312112003 (make a wave for this data) and i have to do tha qpsk for it . how it would look like? im actually confused in a concept that how we take the real and imag parts of the data like i have shown.
i hope u can understand me

 

[Communications_Engineer]

Abdullah, I shall comment on it tonight but here is an advice: Finish one task before jumping onto another.

It seems that you are trying to work on 2 things in parallel (from one of your posts I see that you are also working on P2S converter)

So, relax, complete task 1: QPSK mod and then go to the other one. It will be more efficient

 

[abdullah gill]

u r right i have to do the things in parallel bcz time is short and i hve to do the work....regards