The centre picture in Test Card J is a new version of the picture at the centre of Test Card F, rescanned from the original transparency, to make the colours in the image look more accurate. The centre picture was also re-aligned within Test Card J to put the cross on the noughts and crosses board at the exact centre of the screen, where it was originally intended.
A green square at the top of the screen, which does not appear in Test Card F, is used within Test Card J to facilitate an easier observation of chrominance to luminance delay.
The negative black squares in the left hand step pattern should flash on and off at 1 Hz. This is to aid in the detection of frozen digital links.
As television is now usually broadcast 24 hours a day, the test card is rarely broadcast today. The last known occasion that the card was broadcast on British screens was Wednesday 2 July 2008, when early morning tests of the BBC's back-up 'Rebroadcast System' (RBS) were carried out on BBC Two from 4:00am to 5:00am and on BBC One from 5:00am to 6:00am. This is, however, an annual occurrence, and it is presumed that the test card would reappear during any further RBS tests. Nowadays, BBC One often broadcasts The Sign Zone, several signed programmes and a few films or Antiques Roadshow before linking up with BBC News 24; BBC Two regularly broadcasts BBC Learning Zone late at night, with Ceefax pages during educational holidays and Open University Programmes on weekends. The era of using test cards on BBC thus appears to be over, although there has been sporadic demand for the return of the test cards.
On its last appearance during the early hours of 9 January 2008, Test Card J was broadcast on BBC Two (and later BBC One). There was no music and the audio was replaced with an automated female voice rendition of the Speaking clock, played on the right audio channel, and a steady 1 kHz tone on the left audio channel on BBC One, and a steady 0.44kHz on BBC Two.
Due to the onset of 24 hour television, Test Card J (or any other Test Cards) are rarely broadcast, now only used in engineering tests and transmission problems. Test Card J's broadcast on 9 January 2008 is an example of this. The times before that were 5 January 2007, 23 January 2006 and 7 January 2005, and 9 January 2004. It was also seen on 3 and 4 December 2003, 15 December 2002, and August 2000. Its unscheduled appearances were 22 July 2003, 14 August 2001 and 27 July 2001.