Yes, it is rigged, there are no two ways about that ... there have been many articles about this earlier as well ... including the part about homes being bribed with gifts to keep their TVs on at a particular time. TV is big business in India now, and the money spent on advertising is huge.
An eminent personality like Aamir Khan has openly spoken about how unrepresentative the system is, especially since the number of TVs in India has grown exponentially, and the ratings are based on a grand total of 8000 homes. The smaller the number of homes included, the easier it is to rig the system.
But till a better system comes into effect, this flawed system will stay. And good shows won't get a chance.