User Manual:Setting up DVB-T (terrestrial)

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DVB-T

Contents


DVB-T Theory

DVB-T stands for Digital Video Broadcasting - Terrestrial. The scope of this article is to provide basic understanding of DVB-T and how to setup in Mythtv. DVB-T signals are typically broadcasted by TV towers (like TV towers for analogue reception) on VHF and UHF frequencies over the air. DVB-T signals can be part of the VHF or UHF spectrum, co-existing next to analogue signals. However, many countries are switching these days to digital broadcasting and fully abandoning analogue TV broadcasting. Reasons for switching to digital broadcasting are better picture quality, lower transmitting power needed and the possiblities for Conditional Access (Pay-TV or legal rights) and HDTV.

DVB-T and DVB-S (Satellite) share in common many characteristics. They both share a common a transmitter broadcasting a signal through the air to an antenna/aerial, with bundles of channels (multiplexes) being transmittted by on or more transponders (a frequency on which can be tuned). So, if tuned to a specific frequency , it is possible to receive more than 1 channel on this specific frequency. In contrary to satellite reception, it is not needed to precisely aim to a transmitter. DVB-T signals are all around and can be received using a simple indoor antenna (i.e. a vertical rod) when the transmitter is nearby, or a more sophisticated outdoor antenna in case the transmitter is remote. It is possible to receive DVB-T signals from a transmitter over a distance of 100 kilometer without problems.


Equipment needed

- A DVB-T tuner card or DVB-T USB device. Check out which cards or devices are supported by Linux ([1]). - VHF or UHF antenna, depending on your local DVB-T signals. Small antennas for indoor use are only applicable when a transmitter is nearby, for long distance reception a better outdoor antenna and possible an amplifier are needed. The bigger the antenna contruction is, the stronger the signal will be (however the antenna must be suitable for reception signals you're aiming for, like using a VHF antenna for UHF signals won't give you the best results). - RG6 Coaxial cable and shielded connectors. Good coaxial cable and shielded connectors improve reception dramatically. - Optional: a VHF/UHF amplifier. Poor results from a small antenna will only be improved a little by an amplifier.

Some DVB-T cards are capable putting a 5 Volt phantom voltage on the coaxial cable to feed a small amplifier which can be integrated in the antenna. This voltage can be switched on or of by a jumper or by software settings. Check out your equipment if you need a phantom voltage.


Equipment setup

The setup for receiving DVB-T signals can be really simple:

DVB-T card or device --> Coaxial cable --> Antenna

More complex setups are also possible like:

DVB-T card or device --> Coaxial cable --> multiband amplifier --> VHF antenna

                                                              --> UHF antenna

Or even more complex: DVB-S and DVB-T cards or devices --> coaxial cable --> Satellite diseqc switch with integrated terrestrial input --> LNBs (for satellite)

                                                                                                                --> multiband amplifier --> VHF antenna
                                                                                                                                        --> UHF antenna


MythTV Setup