Jamming TV satellite broadcasts: Who is doing it, and how?
17 November 2012 Last updated at 00:16 GMT
There has been an increase in the number of complaints about the jamming of satellite TV signals around the world.
Broadcasters such as the BBC, Voice of America, France 24, Deutsche Welle and Al-Jazeera have all seen transmissions of their international programmes jammed recently.
The European Broadcasting Union has accused Iran and Syria of being behind the disruption and of attacking media freedom.
But authorities in Tehran and Damascus say that their broadcasts are also being interfered with.
But how does satellite jamming work? And what can be done about it?
Video produced by Thomas Hannen, with Mike Linstead from BBC Monitoring.