Help needed about QPSK using Atmel

[Badar]

Hi
I am working on a project whose objective is to implement QPSK modulator and demodulator.
Input is the clock pulse of any frequency that will work from a pulse generator or an oscillator. It goes into a modulator and then goes into demodulator built on the same PCB that has modulator and have the demodulated output.
I want to use Atmel 8051 microcontroller preferably AT89C2051 using c.
It's my final year project.
I've used google but still i couldn't find any way to use this CPU (AT89C2051) not even any other.
Any encoder and decoder isn't required. The required data rate is 1 kbps. Now i couldn't find any way to get help.
How shall i make this CPU to work as a modulator and then demodulator?
Any help is highly appreciated.

 

[Papabravo]

Try the following App Note for some background and ideas
**broken link removed**
Or this one from Mini-Circuits
https://www.electro-tech-online.com/custompdfs/2008/05/mod11-8.pdf

 

[Badar]

Thanks a lot Papabravo for your concern.
I am beginner to microcontrollers and haven't done anything yet except to run LED's in different patterns.I do have a little background of QPSK but how can i use this microcontroller for it.

 

[Badar]

In this report PLL is used.
There is a block diagram but i couldn't find a way how to implement QPSK using AT89C2051

 

[Papabravo]

Your last link brings up an empty screen. Don't know what the problem is. If we start with the encoder are you going to try for a phase coherent signal or are phase discontinuities OK? If the answer is yes then we take the databits two at a time and feed them to a routine that generates several cycles of a sine wave with one of four initial phases. This can be done with a lookup table that has one of four entry points.

The reverse process will involve multiplying the input signal by a sine wave of the same frequency which yields the high frequency term and the term proportional to the cosine of the phase difference. That term will indicate one of the four possible two bit combinations.

Sounds like a tall order for an 8051 with a fixed point 8 x 8 multiply.