Thanks for confirming your version.
I spent a bit of time yesterday searching for tuning details for NOS Portugal and there is very little information out there. Can I just confirm that they are a cable provider running a DVB-C network? A lot of information on NOS relates to satellite broadcasts (on Hispasat I believe) and I can't find much/anything about the tuning parameters for their DVB-C network.
I did note that for the UK cable provider "Virgin Media", the "Delivery System" is "DVB-C/ANNEX-C" - have you tried that with one of the frequencies from the NOS website? Also remember that the frequencies are in Hz so RTP 1 (196.25) is 196250000 Hz. I think the most important piece of information you are missing is the symbol rate - you can't leave it as zero, and I don't think tvheadend can detect it, so you need to do some digging to try and find the symbol rate for NOS. Do you have access to an official tuner or some other device which might reveal the tuning parameters?
The rest will be trial and error - it might be nice if you manage to work it out to offer your tuning parameters to the community and perhaps they can be included in future builds so any other NOS users don't go through this pain :)