D Major bro u r absolutely wrong. Plz do some research before posting things.
These ratings r on basis of viewership, there r around 20000 meters installed in various TV Homes in India which is connected to the viewer's STB, TV . When viewers watch a channel they have to press a button on the remote of the meter which then records for how long which channels is being viewed and after that reading from all these viewers r taken and ratings r released.
Also the tweets by BARC India , they r in reply to various ratings that an individual has subscribed to. So if say u have subscribed to their English Entertainment Weekly ratings then their twitter handle will automatically tweet to u ratings every week for that genre. Plz don't confuse it with subscription to a channel by an individual. Its more like if u have subscribed to mailers from a company then the company sends u info about their promotions etc. monthly