Conversion of SLC pixel to Digital Number DN

Can anyone please guide (in case of Sentinel-1) ,Is the DN value in case of GRD product an amplitude or magnitude value of each of the pixel of SLC product. Any references will help greatly.

Please study the Sentinel-1 toolbox tutorials for GRD calibration. Standard graphs for GRD-processing should be available via the SNAP graphical user interface.

I think what you are asking is if it is amplitude(abs(a+bi)) or intensity(amplitude^2).

From the description of User Guides - Sentinel-1 SAR - Level-1 - Sentinel Online - Sentinel Online, GRD products contained the detected amplitude and are multi-looked to reduce the impact of speckle.

@mengdahl Perhaps I was not able to frame it correctly. May I know exactly what does the DN value of each pixel represent i.e. how this DN value calculated. Is it just the Voltage Level or anything else basically I want how the DN value is arrived at ? Anywhere that documentation is avaialable ? Kindly clarify.

This should answer most of your questions: