Testing the test pattern
(CBC Still Photo Collection)
This CBC test pattern card was used in the early days of black and white television. Test patterns are typically broadcast at times when the transmitter was active but not program was being broadcast.
Early test pattern cards were literally cards that were put in front of the television camera.
But the famous test cards often appearing in North America in the 1950s and 1960s, have been relegated to history now. The test patterns were used in Canada, following the national anthem sign-off in the evening.
The graphic patterns on the test pattern card served specific purposes and were used to help adjust cameras, home and studio monitors for best perspective, resolution, frequency response, gain, contrast, white level, framing and linearity. Experienced engineers were able to glance at the pattern and quickly know if anything needed careful adjustment before broadcast.
Though this example of a test pattern disappeared long ago, CBC broadcast a modified form of the SMPTE bars, with an additional modulated ramp at the top and a CBC logo animation in place of the Q block, until 2006 when the network moved to 24-hour broadcasting.
Posted on Jul 26, 2011 6:00:00 AM
