INTAM (Indian Television Audience Measurement) uses two methodologies for calculating TRPs. It is the only electronic rating agency functioning in India

The first is frequency monitoring, in which 'people meters' are installed in sample homes. People meters are electronic devices, which continuously record data about the TV channels watched by household members. The 'people meter' is an expensive piece of equipment and is currently imported. It reads the frequencies of TV channels, which are later decoded into the name of the channels. INTAM prepares national data on the basis of these sample homes readings. There is a drawback in the technique, as cable operators frequently change the frequencies of channels before sending signals to homes. It may be very misleading to read a channel according to a particular frequency even if the down-linking frequency is same all over India.[I thought that this was very interesting]. My research indicated that these people meters installed in only 16 top cities in nine states and the panel households exclude lower middle and top income bracket households, which are keen watchers of niche English channels

The second technique is a picture-matching technique, the people meter continuously records a small portion of the picture that is being watched on that particular television set. According to  my research, this method is apparently more reliable (I have my doubts on this as well) but is relatively new to India.  Along with this, INTAM also records all the channels' data in the form of the small picture portion. Data collected from the sample homes is later on matched with the main databank to interpret the TV channel name, in order to produce national ratings.