Which products are you using? If you open a GeoTIFF file, it is only an image without other needed information. The toolbox will not know how to calibrate it. You will need to use a product from a satellite based mission as distributed by a space agency or commercial provider.
One more question. Should change detection using sentinel-1 be done also on a GRD dataset as well? I noticed in a tutorial by PCI Geomatica that sentinel 1 can be used for change detection determinations.
Aren’t SLC images necessary for calibrating to dB? Doing radiometric calibration on GRD files doesn’t have dB as an option, at least in my limited experience.
I think I may have derived the answer from elsewhere in the forum, here to be exact. I am interpreting the equation at the top of page 8 as indicating that:
sigmaNought[dB] = 10 * log10(sigmaNought)
where sigmaNought is the output of GRD Radiometric calibration. Is this correct?