I need this MobTV - Receiver / converter for digital TV on computers and notebooks.

With the advent of digital TV in Brazil, it became possible to receive television signals in computers and notebooks.

This requires a small device, usually connected to a the USB port, which captures and transmits the signal to the processor (the technical name is receiver, since it only receives and transmits; Converter, used in analog TVs, has the role of making the conversion from analog to digital signals).
As computers are naturally designed to handle digital signals, this device is much simpler and cheaper than the converters (or set-top boxes) used to adapt the digital signal to analog TVs.

In addition, there are other advantages worth mentioning: The TV shows can be stored on the computer HD (see settings MobTV, below), hence the programs become bytes of data, and you can manipulate them as any another set of bytes (all this in theory, it is necessary to wait and see what occurs in practice - read more about programming the recording of digital TV): Watch the programs several times, edit them, copy them into other media, transmit them via internet, etc.

For the reasons explained above, the MobTV (and other receivers USB arising) certainly will be cheaper than the converters set-top box.