Test card features
Some elements present on the FuBK test card are: [12] [4]
- Cross hatch - makes up the background of the table, with 19x15 white lines over a dark gray (25% luminance) background, allowing adjustment of CRT convergence and focus;
- Circle - provide a way to correct vertical and horizontal raster scan geometrical distortions;
- Colour bars - EBU colour bars at 75% luminance (75/0/75/0) to adjust colour saturation and purity
- Grey staircase - five bars (0%, 25%, 50%, 75%, 100%) that allow setting brightness, linearity and contrast control
- 2T convergence cross - check for signal reflections and group delay, help with geometrical image centring
- Multiburst - four grating with sine curves at 1, 2, 3 and 4.433 MHz, as a test of horizontal resolution
- Black section- check for reflections, transient response and group delay
- ±V/ +U ramp - two lines that allow checking PAL decoder linearity with UV signals
- +V/ ±U anti PAL - two achromatic fields to test the PAL decoder delay line
On PAL broadcasts, with a maximum displayable video bandwidth of around 5 MHz, individual lines should just be visible in all Multiburst gratings. In other situations, like a VHS recording with reduced bandwidth, they become more and more indistinct, merging into a grey area.
The two special achromatic fields should be displayed as grey if PAL decoding is functioning correctly. If not, colour will be seen on these areas, [4] as shown in the off-air screen capture of ARD Das Erste test card, visible on the "Usage Gallery" at the end of this article.
Variations
4:3
- A variation (used by Doordarshan [13] in India, by PTT-NL/Nozema/NOS [14] in the Netherlands, TVR in Romania, YLE [15] [16] in Finland, Sky One in the United Kingdom and in West Germany [17] [18] ) simply omitted the centre circle. This variation is also anecdotally called "Simplified FuBK".
- Another variation adds a second set of colour bars (replacing the ±V/ +U Ramp and +V/ ±U Anti PAL sections) and flips the middle downward triangle. This was used by IRIB in Iran.
- Another variation that adds border castellations and changes the middle downward triangle to a simple vertical bar, used by Kanal 2 [19] in Denmark, Rupavahini [20] in Sri Lanka, Televerket Kabel-TV in Sweden and on some German channels. [21] [22] [23] [24] [25] Used with further modifications and added graphics by al-Jamahiriya TV (Libya). [26]
- Another modification, again omitting the circle but including a grid cross in the middle and slightly different resolution gratings, was known to be used on some TV transmitters in Belgium and the Netherlands. [27]
- A monochrome variant, omitting the centre circle and replacing the colour bars with a black box showing the transmitter name and channel, as well as an on-screen line gauge replacing the ±V/ +U Ramp and +V/ ±U Anti PAL sections near the bottom, was used on some DBP-operated TV transmitters in West Germany in the 1970s. [28] [29] [30]
- While not exactly a variant, the Grundig VG 1001 pattern features many of the FuBK test elements, like the colour and grey bars, PAL check area and gratings. This allows it to be used to perform the same adjustments. [9] This pattern was used by a few channels like BRT (Flemish Community of Belgium), [31] SDR (southwest Germany), [32] Polsat (Poland), [33] MVQ-6 (Mackay Region, QLD, Australia), [34] at the headends of many Finnish cable TV providers, [35] on experimental satellite test transmissions involving the Orbital Test Satellite in the early-1980s, [36] as well as on point-to-point cable and satellite feeds in the UK, [37] France, Austria, Italy, Germany, Luxembourg and Belgium. [38] A heavily modified version of the VG 1001 pattern was used for SECAM transmissions by Bulgarian National Television (BNT) [39] during People's Republic of Bulgaria era and also later in PAL by NOVA from its launch in 1994.
16:9
In the 1990s, a FuBK variant in the 16:9 aspect ratio format was developed for the PALplus and (HD-) MAC standards and was used by some channels such as ARD. [40] [41] Crosshatch was changed to a 25x15 grid, and geometric markings for the central 4:3 safe area were included, with the other details being generally the same as on the original version. This pattern could be generated by the Grundig VG 1100 video generator, introduced around 1995 [42] [43] as well as the PM5644/86 [44] and the digital PT5300 from DK Technologies (with an optional hardware upgrade). [45]
Variation Gallery
Recreation of the FuBK test card, omitting anti-PAL lines.
Recreation of the FuBK square variant omitting the centre circle. ("Simplified FuBK")
Recreation of the modified FuBK test card used by IRIB.
Recreation of the FuBK test card variation that adds border castellations and changes the middle downward triangle to a simple vertical bar.
Recreation of the Telefunken FuBK test card square variation omitting the circle, including a grid cross in the middle, and with slightly different gratings.
Recreation of the FuBK monochrome variant, omitting the centre circle and replacing the colour bars with a black box showing the transmitter name and channel, as well as an on-screen line gauge replacing the ±V/ +U Ramp and +V/ ±U Anti PAL sections near the bottom.
Recreation of the heavily modified Grundig VG 1001 variant used in Bulgaria.
Recreation of the 16:9 / PALplus variation of the FuBK test pattern, same as the one generated from a Grundig VG 1100.
Widescreen FuBK pattern with anti-PAL and clock cut-outs. Generated by a DK-Technologies PT5300.
