The Philips PM5544 is a television pattern generator, most commonly used to provide a television station with a complex test card commonly referred to as a Philips Pattern or PTV Circle. The content and layout of the pattern was designed by engineer Finn Hendil in the Philips TV laboratory in Copenhagen under supervision of chief engineer Erik Helmer Nielsen in 1966-67. The equipment, PM5544, which generates the pattern, was then made by engineer Finn Hendil and his group in 1968-69.  Since the introduction of the PM5544 in the early 1970s, the Philips Pattern has become one of the most commonly used test cards, with only the SMPTE bars and the BBC Test Card F coming close to its usage.
The Philips Pattern was later incorporated into other test pattern generators from Philips themselves, as well as test pattern generators from various other manufacturers.
The BBC occasionally uses a modified version, Test Card G, which it first used in 1971, and although it was also used for a period of time by the IBA it eventually abandoned the Test Card G and developed its own test card called the ETP-1 which was brought into use on ITV from 1979 onwards. Many broadcasters using a 625 line PAL system use some form of the Philips Pattern.
Since the Philips Pattern is geared towards the PAL colour-coding system, this test pattern is uncommon among NTSC broadcasters, though some, such as CBFT and CBMT in Canada, WBOY-TV and WNYW in the USA, DZBB-TV in the Philippines, Myawaddy TV in Myanmar, MBC in South Korea, and Rajawali Televisi, Detik TV in Indonesia have used a 525 line version of it in the past. The Japanese national broadcaster NHK also did use a 525-line version of the said test card, albeit with slight technical differences in specifications as compared to those used by the American and Canadian broadcasters.
In Spain, the PM5544 test card is used by the various autonomous and private channels since the early 1980s (examples include TV3, El 33, Telemadrid, Antena 3, Canal+ Spain, etc.), although not by the national public broadcaster TVE, which has used its own colour test card since 1975.
Some television stations have also been seen to have used slightly modified versions of the Philips Pattern, most notably the inclusion of a digital clock and/or date, as well as the station ID, in it. This practice is common in Asia and in some parts of Europe.
A widescreen capable Philips Pattern generator, PM5644, was introduced by Philips in the 1990s. The widescreen version of the test card retains the signals present in the original, and features additional signals to test further aspects of signal and picture quality, as well as overscan markings. As with its predecessor, the widescreen Philips Pattern was adopted by various other manufacturers of test pattern generators.
Because of the number of manufacturers and generators made over the years to produce the Philips Pattern, various configurations and modifications exist. While the basic specifications normally remain consistent, there are often small variations to the Philips Pattern depending on the generator used to produce it, as well as how the broadcaster has chosen to configure it.
- http://www.pembers.freeserve.co.uk/Test-Cards/Test-Card-Technical.html#PM5544. Retrieved 2011-04-22.