Help with MATLAB HDL AWGN Generator and IQ sample format mismatch

[ahmedelbushra]

Hello everyone,

I’m working on integrating the MATLAB HDL AWGN Generator with IQ samples generated from the openofdm_tx Verilog code.

The AWGN block outputs noise samples in the format sfix18_En14, which means the values are mostly fractional (ranging approximately between –1 and +1). However, the IQ samples from openofdm_tx are in sfix16_En0 format — they are integer values without any fractional bits.

I’ve tried several scaling and normalization techniques to align the formats, but I haven’t been able to make it work correctly yet.

Could anyone explain:

What the format or numerical meaning of the IQ samples from openofdm_tx actually is?

What would be the best way to properly combine or scale the AWGN output with these IQ samples in fixed-point Verilog?

Any guidance or examples would be greatly appreciated!