The black and white monoscope test pattern is one of the most famous icons of early North American television. Originated by RCA in 1939 when commercial TV broadcasting first began, this pattern was generated using a special tube called a monoscope.

Because these tubes could only handle black and white, shades of grey had to be simulated using either a halftone dot pattern or a pattern of fine lines.

Originally, test patterns were physical cards at which a TV camera was pointed. The pattern would be broadcast at times when the TV transmitter was active, but no programming was being broadcast (often at the start or end of the broadcast day).

Over the years there have a been a variety of different test patterns used, including ones for colour television which came to Canada in the 1960s.