Test card
A test card, also known as a test pattern in North America, is a television test signal, typically broadcast at times when the transmitter is active, but no programmes are being broadcast.The test card usually has a set of line-up patterns, enabling televisions to be adjusted to show the picture correctly. (Compare with SMPTE color bars). They would also typically be broadcast to a background of specially composed music, to avoid having to pay licencing fees for existing compositions. There is now a cult following for test-card music.
The most famous British test card is Test Card F and its successor Test Card J, used on the BBC and ITV from the beginning of colour broadcasts in the late 1960s. See separate articles for full details.
Formerly a common sight, test cards are now only rarely seen. Two things have led to the demise of the test card:
- Modern microcontroller-controlled televisions rarely if ever need adjustment, so test cards are much less important than previously.
- The financial imperatives of commercial television broadcasting mean that air-time is now typically filled with programmes and commercials 24 hours a day, and non-commercial broadcasters have to match this.
See also
- Images of test cards
- Trade test transmission
