[3] There are several techniques for pirate TV broadcasting, most of which have been made very difficult, or obsolete, by better security measures and the move to digital television.
This attack is generally now prevented by the channels broadcasting 24 hours per day (e.g. showing test cards instead of closing down), by using satellite feeds instead of repeating terrestrial signals, by electronic security to lock the relay to the authorised source, or by the switch to digital television.
In this scenario, a man-in-the-middle attack is performed upon the source material, such that authorized official transmissions are fed with unauthorized programming from the central studio or play-out facility.
For example, a link feed (e.g. outside broadcast) is hijacked by a stronger pirate signal, or pre-recorded media (such as videotapes or hard drives) are swapped over for unauthorised content.
As with most pirate radio stations, reasonably powerful VHF/UHF transmitters can be built relatively easily by any sufficiently experienced electronics hobbyist, or imported from a less strict country.
The primary challenge to this technique is finding a suitable yet inconspicuous vantage point for the transmission antenna, and the risk of getting caught.
Viewing numbers may be much smaller than analogue pirate TV since re-tuning a digital television may be an entirely automated process which may ignore unauthorized multiplexes, or place such channels in an obscure section of the electronic program guide.