ETP-1 was a test card

Test card

A test card, also known as a test pattern in North America and Australia, is a television test signal, typically broadcast at times when the transmitter is active but no program is being broadcast...

 designed and used by the Independent Broadcasting Authority

Independent Broadcasting Authority

The Independent Broadcasting Authority was the regulatory body in the United Kingdom for commercial television - and commercial/independent radio broadcasts...

 (IBA). After test transmissions from the IBA's Engineering Regional Operations Centre (ROC) in Croydon from 1978 it was phased in on ITV

ITV

ITV is the major commercial public service TV network in the United Kingdom. Launched in 1955 under the auspices of the Independent Television Authority to provide competition to the BBC, it is also the oldest commercial network in the UK...

 over a period starting from 1979, replacing Test Card F

Test Card F

Test Card F is a test card that was created by the BBC and used on television in the United Kingdom and in countries elsewhere in the world for more than four decades...

. After ITV went 24 hours in 1988, the card ceased to be seen on the channel.

It was also seen extensively on both Channel 4

Channel 4

Channel 4 is a British public-service television broadcaster which began working on 2 November 1982. Although largely commercially self-funded, it is ultimately publicly owned; originally a subsidiary of the Independent Broadcasting Authority , the station is now owned and operated by the Channel...

 and S4C

S4C

S4C , currently branded as S4/C, is a Welsh television channel broadcast from the capital, Cardiff. The first television channel to be aimed specifically at a Welsh-speaking audience, it is the fifth oldest British television channel .The channel - initially broadcast on...

 during both the pre-launch tests and during the downtime of those channels, due to their limited hours early on. After launch, it was alternated with in-vision teletext

Teletext

Teletext is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules...

 services from ORACLE

ORACLE (teletext)

ORACLE was a commercial teletext service first broadcast on ITV in 1974 and later on Channel 4 in the United Kingdom, finally ending on both channels at 23:59 GMT on 31 December 1992....

 and 4-Tel/Sbectel

Sbectel

Sbectel is the name of S4C's former ancillary teletext service. It was named after the Welsh language S4C programme magazine called Sbec which was originally a pull-out of the TV Times in the ITV Wales area.-Content:...

. On these channels, it was captioned either IBA:CH4 or IBA:S4C, with lines above and below this indicating the card was being generated by the channel, the absence of these lines meant it was generated at the transmitter. After the splitting up of the IBA in 1990, the captioning was changed to NTL

Arqiva

Arqiva is a telecommunications company which provides infrastructure and broadcast transmission facilities in the United Kingdom and Republic of Ireland. The present company, with headquarters located at Crawley Court in the village of Crawley, Hampshire, was formed by National Grid Wireless...

:CH4/NTL:S4C. ETP-1 was last broadcast on December 31, 1992 after which Channel 4 showed 4-Tel on View and gradually increased its late night programming - eventually going 24 hours a day in 1997. S4C now broadcasts black screen and tone when off-air.