User Manual:Setting up DVB-T (terrestrial)

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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. An amplifier is mostly used to amplify the signal on the coaxial cable to have enough power for switches etc. Poor reception results from a small antenna will only be improved a little by an amplifier. Not only the bad signal is amplified, also the noise will be amplified, resulting into a strong but useless signal.

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


Equipment setup

Horizontal or vertical orientation: DVB-T signals can be horizontally or vertically oriented. Check this out at your broadcaster since this may have impact on your antenna 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/UHF antenna

Or even more complex: DVB-S and DVB-T cards or devices --> coaxial cable --> Satellite diseqc switch with integrated terrestrial input --> multiband amplifier --> UHF antenna


MythTV Setup

For more general information, see User Manual:MythTV structure

General

For General Setup, see User Manual:Detailed configuration Backend

Capture Cards

Pictures are yet to be inserted.

The "Capture Cards" screen allows you to select your tuner device and scan for channels.

Notes:

  • Recording options let´s you define options like maximum number of simultaneous recordings, tuning delay and the possibility to let the card scan for EIT data (electronic program data). Useful for Multirec.
  • Some DVB/T cards need some time to tune. Start with the default settings, you can change this later if needed.
  • Diseqc is not intended nor usable for DVB-T, you can ignore this.
  • Note that if you use a CAM (Conditional Access Module) for Pay-TV, it might be impossible to record more than one stream simultaneous in a multiplex. This is limited by the CAM. Some experiments might be needed to find out what is possible for your situation.

Video Sources

Pictures are yet to be inserted.

The "Video Sources" screen allows you to define where MythTV gets the channel information for the EPG (Electronic Program Guide) for your capture card. This may vary with region- try searching this wiki, or checking [external links] for region specific information.

Notes:

  • For each card an entry is needed.
  • The option sended EIT-data is fine, but not every TV station will send this data, or the data may not be reliable.
  • If you want to use icons for specific channels, use the XMLTV options.

Input Connections

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The "Input Connections" screen allows you to link your video sources (EPG data) to your capture cards.

Notes:

  • In this particular section it is time to get your channel info at hand.
  • Perhaps you have made already a channels.conf file with all necessary information, or you might have the most important frequencies etc. written down.