anyone can give me some help about Analog TV RF Spec?

anyone can give me some help about Analog TV RF Spec?
Now I meet some problem about Analog TV ( here I define the Noise Figure of The TV tuner is 5dB)
1. How Can I calculate the sensitivity of the PAL format with 6MHz Channel Bandwidth?
(For I don't know the CNR which the Baseband Demodulate required )
2. How Can I calculate the sensitivity of the NTSC format with 6MHz Channel Bandwidth?
(For I don't know the CNR which the Baseband Demodulate required )
3. Can give some papers about the analog RF system Spec?
4. Any helpful link can give me ?

thanks very much with your kindly help
Best R