VHDL algorith/code for implementing QAM on FPGA

[Tony A]

Hello Everyone,
I am working on designing a digital modulator that will implement QAM
on FPGA.

The FPGA will be programmed in VHDL to modulate an input
signal(maybefrom a function generator)

A D/A converter will convert the digital signal to an analog one that
canbe transmitted.

Anyway, what I need now is algorithm and/or VHDL code that will carry
out the QAM on FPGA.

Any help is greatly appreciated

Anthony

 

Tony A wrote:

Hello Everyone,
I am working on designing a digital modulator that will implement QAM
on FPGA.

The FPGA will be programmed in VHDL to modulate an input
signal(maybefrom a function generator)

A D/A converter will convert the digital signal to an analog one that
canbe transmitted.

Anyway, what I need now is algorithm and/or VHDL code that will carry
out the QAM on FPGA.

Any help is greatly appreciated

Anthony

 

Hi,

You just look at two bits at a time and select the correct symbol.

Example:

bit_vec(1:0) contains two adjacent bits of your inputstream.
(i,q) reperesent complex output symbol

case bit_vec is
when "00" => i <= 1; q <= 1;
when "01" => i <= -1; q <= 1;
when "11" => i <= -1; q <= -1;
when "10" => i <= 1; q <= -1;
end case;

Regards,
Mats