The history of the BBC trade test transmission (part 2/4)

First published in 2008. Last updated: 4th August 2020.

Our history of the BBC trade test transmission continues.

Test Card F goes electronic

With in-vision teletext now dominating non-programme airtime, what of the future of Test Card F? Well, back in the autumn of 1982, BBC Engineering announced plans to create an electronic version of Test Card F. This short article from their in-house magazine outlines the proposal:

The BBC has radiated Test Card F during trade test transmissions for a number of years but its future use became uncertain partly due to the difficulty of obtaining quantities of high quality slides. Consultations with the receiver trade via the British Radio and Electronic Equipment Manufacturers’ Association (BREMA) revealed that many service engineers prefer Test Card F to other purely electronic patterns. This is thought to be because the central picture of a young girl gives a subjective assessment of picture quality and aids the setting of colour saturation.

For future use, Designs Department are producing an equipment which stores the test card in digital form in order to overcome the problems of slide duplication and the need for a slide scanner. Data will be held in YUV form using eight bits and 13.5/6.75 MHz sampling frequencies. All of the geometric patterns will be derived from computed picture samples calculated by programs which take account of the requirements for different rise times in the corner diagonals, the circle and the frequency gratings. This data, which describes an essentially perfect test card, will be combined with the central picture samples obtained by a YUV ‘frame grab’; techniques for noise reduction on this central Image will be explored.

Captions for network identification will be added to the complete test card from separate integral digital generators so that the one equipment will deliver several differently annotated outputs, all of which are coded PAL. The first equipment is expected to be in service by mid-1983.

BBC Engineering

However, whatever the reasons, the electronic test pattern did not materialise on air until May 1984. The timing of the deployment of the new equipment was perhaps unfortunate, what with Pages from Ceefax now replacing virtually all daytime trade tests. But, the new kit had many other uses within the BBC too.

Contrary to much of what is written online about the introduction of the electronic version of Test Card F, it did not immediately permanently replace the slide format. The electronic pattern was introduced on an experimental basis in May 1984. The slide version – and Test Card G – were used on air for a while longer. Although Pages from Ceefax had largely replaced the test card, Ceefax was prone to technical issues. In such circumstances, the test card stepped in to cover.

No major design alterations were made for the electronic version of the test card. There were a couple of cosmetic changes: a new font for the designation letter; and the colour bars along the top, which now completely replaced the black and cyan blocks.

Internally, most PAL coders inserted a couple of lines of colour bars within the vertical interval. Known as IRS bars (Insertion Reference Signal), this allowed for quality checks at any time, and not just during line-up, similar to the ITS (Insertion Test Signal) on transmitted signals.

The coder for the slide version of the test card was modified to insert a fat band of colour bars at the top of the picture but had the disadvantage of hiding the top of the arrow-head that pointed to the edge of the picture. When the electronic test card was created, the colour bars were part of the frame store that made up the image and so they were extended down to the top white bar of the frame to look tidier. The arrow-head was overlaid on top of the central magenta bar, thus restoring that feature.

Electronic Test Card F was showcased at the 1984 International Broadcasting Convention (IBC). And BBC Engineering publicised the development in their quarterly magazine, in autumn 1984:

Test Card F has been radiated by the BBC during trade test transmissions for a number of years: it is also widely distributed within Television Centre providing a quick and convenient means of confirming the correct operation of numerous items of video equipment. Its future use had become uncertain, partly owing to the difficulty of obtaining high-quality slides but also because of the need for a dedicated slide scanner. The latter is of course expensive in terms of capital and requires routine monitoring and adjustment if excellent results are to be obtained.

The digital Test Card F generator displayed at IBC (international Broadcasting Convention) replaces both slide and scanner whilst requiring no routine maintenance. The equipment contains a read-only picture store conforming to the 4:2:2 coding standard (CCIR Recommendation 601), having the luminance signal sampled at 13.5 MHz and the colour difference signals at 6.75 MHz. A single 4U-high 19-inch rack takes mains and pulse inputs to deliver digital and analogue YUV test card together with a PAL signal from an integral coder.

All of the geometric patterns were generated by computer techniques with reference to the original drawings. Edges were both horizontally and vertically anti-aliased to give the most accurate realisation of Test Card F. The central picture of the girl was copied from a slide by means of a YUV ‘picture grab’. and the resulting data were inserted into the geometric pattern during the computer preparation process. The combination of the real picture and computer-generated patterns provides a stable, high-quality source for a well-known test signal.

The original central picture has been retained as it provides valuable information for assessment of flesh tones, overall saturation, luminance-chrominance timing and picture monitor convergence etc.

BBC Engineering

The autumn 1982 article mentioned that captions for network identification would be added to the test card via separate integral digital generators. However, during its first few months of on-air use, the new electronic test card was broadcast without a channel identification caption. A rather crude, temporary solution eventually materialised (the first image below). However, it wasn’t long before they were replaced by the proper channel logos.

There was a minor glitch with the channel logos, when they were first added: they weren’t vertically centred between the white lines above/below them. This was addressed in 1985, but, unfortunately, for BBC Two, the horizontal centring was knocked off slightly. The change is apparent when comparing image two and three above, from late-1984 and mid-1989 respectively.

The electronic Test Card F was a revelation, as it was perfectly linear and had a flat grey background, unlike the old slides, which always had a bit of shading. Digitising an image was quite difficult in those days and rather than try to scan the original photo again, the BBC’s research department (who created the electronic version) worked with the computer graphics workshop at TV Centre and grabbed an image of the current test card slide on Quantel Paintbox. They took the data file back to their base at Kingswood and incorporated the central picture into the computer-generated pattern.

However, so that there was a clean and precisely-defined white circle around the picture, they had to zoom in a little to hide the old one (circle) on the slide. Despite their best efforts, the picture on the electronic test card always looked a little desaturated (pale).

In 1985, BBC One’s on-screen presentation was updated – the new look debuted from 7pm on 18th February. The test card was updated with the new channel logo – the earliest sighting we’re aware of is Sunday 7th April 1985.

The kit that produced the electronic test card also had the ability to add an on-screen countdown (as demonstrated in the images above). Since the 1970s, a ten-minute countdown to the next programme was regularly displayed over the test card. The updated version of the countdown (introduced with electronic TCF) counted us into Ceefax AM on BBC One (though its use was sporadic). Sightings of the countdown on BBC Two post-May 1983 were few and far between. We believe the countdown was largely retired by the early 1990s. Though there is evidence of it popping up as late as October 1996:

VIDEO: Pages from Ceefax (BBC One). The test card countdown can be seen in the opening seconds of this clip. TX DATE/TIME: 7th October 1996, 5.51am. SUPPLIED BY: YouTube Channel – Jez C. COPYRIGHT: BBC.

On Easter Sunday (30th March) 1986, BBC Two got a sophisticated new look. Initially, the striped ‘BBC2’ logo was removed from the channel’s test card. But it would soon reappear (first confirmed sighting we’re aware of is late-May 1986).

The striped ‘BBC2’ logo (of the 1979 – 1986 era) would remain on the channel’s test card until February 1991. It’s not clear why the ‘TWO’ logo (1986 – 1991) was not used on the test card. However, the ‘TWO’ lettering was generally never accompanied by a BBC logo. Having a ‘TWO’ logo and no ‘BBC’ branding on the test card may have been deemed problematic.

Anecdotally, the ‘TWO’ logo is believed to have appeared on a festive version of Test Card F, on Christmas morning 1988.

On the morning of 16th February 1991, BBC One and BBC Two on-screen presentation was revamped. The channel identification on the test card was updated to reflect the new channel logos.

Sadly, the horizontal positioning of the logos was somewhat off – particularly on the BBC Two version.

The test card kit would remain untouched for the next six-and-half-years. Until the morning of 4th October 1997, when the BBC began the on-air implementation of one of the biggest branding projects it had ever undertaken. A fundamental aspect of this initiative was the creation of a new BBC logo. The two TV channels implemented new on-screen presentation, incorporating the new logos.

The test card was updated with the new channel logos. Although each channel initially had their own branded version of the test card, at some point during 1998 (date TBC), a generic ‘BBC’-branded version of Test Card F appeared.

In November 1997, BBC One began broadcasting 24-hours-a-day, so the test card was rarely seen on that channel again – with the exception of the annual RBS transmitter tests.

In March 1998, digital widescreen tests broadcast by the BBC on Astra 1D saw the use of a new 16:9 test card. Labelled ‘BBC WIDESCREEN’, the test card had no designation letter. But it was clearly a modified version of Test Card F.

On 6th November 1998, the widescreen pattern appeared during an edition of Have I Got News for You.

In November 1999, an updated version of the widescreen test card appeared – and now had a designation letter. Test Card W included some new elements:

  • A small green square in the letterbox, to highlight luminance to chrominance delays;
  • Two pairs of flashing dots in two of the greyscale squares – the animation helps demonstrate that this is a live, “active” visual and the video signal has not frozen;
  • The coloured bars at the top – and now down the right side also – are 100% saturation, as opposed to 95% on TCF;
  • Mirrored arrows down each side indicated 4:3 and 14:9 positions;
  • The final frequency grating is now 6Mhz;
  • Luminance and chrominance sawteeth along the bottom;
  • Pure colour difference castellations on the far left.

On 20th November 1999, a surprising development: the unveiling (on BBC Two) of an updated 4:3 version of the test card. An update that merited a new designation letter. Test Card J was born. With the arrival of digital widescreen television the previous year, a new 4:3 design was somewhat unexpected.

Test Card J was basically Test Card F with some features from Test Card W – namely the green square in the letterbox, and the flashing dots in the greyscale squares.

Why ‘J’? Well, the BBC already had a Test Card G (their modified Philips PM5544, discussed elsewhere in this article). There was also an ‘H’ – an internal line-up card. On a design that includes lots of vertical and horizontal lines, ‘I’ perhaps seemed inappropriate. Hence, we arrive at ‘J’.

According to Barney Wol’s website (no longer online), when Test Card J and Test Card W were being put together, the original 2.25″ slide of Carole Hersee and Bubbles was rescanned. The updated image was less tightly cropped than on Test Card F and was carefully realigned to ensure the ‘x’ in the game of noughts and crosses is exactly at the middle of the screen. We can now see that Bubbles is holding a stick of chalk – this was cropped out of view on Test Card F.

Another difference in the newly rescanned photo is that Bubbles’ green body covering is less saturated than on Test Card F. Originally, this covering was actually blue but a green alternative was made, so that the photo catered for the primary colours. But during the production of the original Test Card F, the body covering was deemed not green enough, so it was retouched to create the much brighter green that we became familiar with.

On 1st December 2007, an HD (1080-line) version of Test Card W appeared, with the launch of the BBC HD channel. The HD test card did not have an official designation letter, but is unofficially referred to as Test Card X. The ‘BBC HD 1080 lines’ test card was shown daily on the channel, as part of its programme barker, shown outside of programme hours.

The BBC HD channel closed on 26th March 2013. This version of the test card has rarely, if ever, been seen on any of the UK BBC TV channels since. If you know different, please let us know.

In 2016 (date TBC), an unexpected development: BBC Two’s overnight programme highlights barker had one minute of test card added to it. Again, the test card had no designation letter but it’s clearly yet another variation of Test Card W.

The section underneath the circle has been altered to accommodate a large ‘BBC TWO’ logo (an out-of-date Gill Sans version – also not horizontally centred). The card included an animating white bar, accompanied by an audio ‘click’ (heard when the bar reached the implied ‘0’ in the numbered markings (also not horizontally centred)). The click was the only sound heard whilst the card was on screen. The bar animation and audio signal are used to determine if the audio and video signals are properly synchronised.

An update to the BBC Two programme barker in 2019 (date TBC) resulted in the removal of the test card alas. So, once again, there’s no outlet for airings of the test card on UK BBC TV channels.

Continue to Part 3 >>>




Posted by The Clean Feed Team

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