even your public antenna can receive the signal from china, the maintanence technican won't tune the antenna for the bldg to receive CCTV-1.....coz they most of the time, if you receive cctv-1 clear, the signal of local channel droped.....
another reason is that...
cctv-1 broadcasted in VHF and local channel in UHF
as far as i know..the public antenna system don't amplify VHF signals...but juz UHF signal...
where do you live???
do you have a window facing north and it's open upfront.....without barrier...
it's very very important.......coz you can install a cheap and small int. antenna and try to receive cctv-1