Tutorial DVB T2 TV with a HackRF

Digital TV in a few clicks, plus how to fix a picture that breaks up.

What you need

• OnAir and a HackRF One or Pro (see HackRF); on Windows the WinUSB driver.
• A TV antenna with a clear view toward the transmitter. Height matters more than anything else.
• To know that your country uses DVB-T2 (Europe, Middle East, Africa, Asia, Australia). DVB-T, the older standard, uses the same screen: the DVB standard is detected automatically.

Steps

1. Plug in the HackRF and the antenna and start OnAir. If the setup wizard asks, give your country: it picks the right TV standard.
2. In the mode list choose DVB (group TV).
3. Open the Scan tab and run the channel scanner. It finds channels automatically. (You can also type the frequency of a channel you know.)
4. Press Start on the frequency you chose. A TV channel needs roughly one million samples per second per MHz of channel width, so an 8 MHz channel needs a radio that samples a little above 8 Msps; the HackRF reaches 20 Msps and OnAir tells you next to the source if the rate is too low.
5. Wait for the receiver to lock. The status shows the signal-to-noise ratio and the error counts, and a single quality score.
6. Open the TV tab, click a service and watch. The player has sound, subtitles, teletext, a programme Guide and multiple audio tracks.

If the picture breaks up

1. Use Auto-tune for the gain, or Optimise gain: it sweeps the radio's whole gain range, measures the SNR and keeps the lowest gain within 0.5 dB of the best one that does not overload the converter. Undo gain goes back.
2. Watch the echo (multipath) detector in the status: echoes from buildings are the usual cause of a broken picture. Move the antenna and watch the quality score.
3. The Antenna tab has a direction finder that helps you aim the antenna.
4. OnAir repairs short signal dropouts automatically so a weak signal stays watchable.

Keep it

• On the Stream tab record the stream to a file or send it out over UDP. Release 0.2.6 adds recording a service from the TV tab, with pause and a live buffer.
• The built-in network tuner streams your channels to VLC, phones, Plex or Jellyfin over your home network, as a plain stream or as HLS for browsers and phones.
• On a Mac you can cast the playing service to an Apple TV or AirPlay TV.

Limits. Encrypted (scrambled) services cannot be decoded. T2-Lite is decoded like any other T2 signal and was checked on simulated signals, not yet on a real T2-Lite broadcast.

Related: DVB-T2 and DVB-T, Troubleshooting.