Philips circle pattern

Lore & Background

The Philips circle pattern was developed in the Philips TV & Test Equipment laboratory in Amager near Copenhagen, which moved to Brøndby Municipality in 1989. The pattern built on previous work with the monochrome PM5540 pattern. The same team later developed the Spanish TVE colour test card in 1973. Unlike earlier test cards produced by a live camera or monoscope filming a printed card, the PM5544 generates the pattern fully using electronic circuits with separate paths for Y, R-Y and B-Y colour components, allowing engineers to reliably test and adjust transmitters and receivers for signal disturbances and colour separation, particularly for PAL broadcasts.

Reader's Guide

The Philips circle pattern provided reference levels of black, white and colour saturation, enabling receiver adjustment. It also allowed correction of displayed image geometry such as centering and circle proportions. The pattern included a circle with black/white and colour information, a square wave, a colour bar, crossed lines for interlace checking, definition lines at various frequencies, a staircase greyscale, and a white black step with needle pulse. Variations exist for SECAM, NTSC, PAL-M, PAL-N, and widescreen 16:9 formats. The BBC developed Test Card G as a quasi-Philips pattern via physical modification of standard PM5544 generators. An HD version was developed for the PT5300 but never formally offered for sale. Mainland Chinese broadcasters used heavily modified versions called the GB2097 inspection chart and anecdotally the PM5549.

Did You Know?

• The Philips circle pattern was designed by Danish engineer Finn Hendil in 1966–67.
• The first generator, the PM5544, was built in 1968–69 and generated the pattern entirely electronically.
• The pattern has variations for PAL, SECAM, NTSC, PAL-M, PAL-N, and widescreen 16:9.
• BBC Test Card G was a quasi-Philips pattern created by modifying standard PM5544 generators.