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Digital Satellite Hidden Test Patterns


There are usually a few test signals about on Sky Digital. They don't appear on the EPG, and have to be programmed into the Digibox manually. Here's a few of them, past and present:

This is a Philips PM5544 test pattern. Strangely, it doesn't have a station ID anywhere.

Taken: 9th April 2000

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sub-TV Image

A test for S4C Digital. A distinct lack of imagination here! :-)

Taken: 20th June 1999

Taken: 9th April 2000

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sub-TV Image

The colour bars from the ITN News Channel - with a superimposed menu, perhaps for controlling the pattern generator.

Taken: 16th July 2000

The MB1 Colour bars. "Technical Problems" is a bit of an understatement - this station was off-air for two weeks!

Taken: 17th July 2000

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They even have to ruin test patterns with DOGs now! :-)

Taken: 21st August 1999

Quite what "Facility Line" means is anyone's guess....

Taken: 24th November 1999

Facility Line
NTL Newman St.

This is sourced from National Transcommunications Ltd. (NTL) the company that the engineering branch of the IBA became. It's now owned by an American company, I believe.

Newman Street is probably where the pattern originated.

The dashed lines move from left to right on-screen.

Taken: 24th November 1999

One for the puritans, this: a plain old colour bars pattern.

Taken: 1999

Colour Bars
MPEG Test

This pattern tests the effectiveness of the MPEG compression. MPEG works by only encoding the parts of the picture that are changing from one frame to the next, and uses some predicting algorithms to predict the next frame.

There is some white noise on the test pattern which completely flummoxes the encoding procedure because white noise is random and takes up a lot of bandwidth to encode. The outcome of this is that the rotating circles at the bottom, which are moving from side to side, flicker quite badly.

Most of the chart moves in some way, to try and catch out the MPEG, but there are some familiar parts of the chart, notably the greyscale (which moves) and the gratings (which are stationary).

There is also a small box which changes between "IfN" whatever that stands for) and what looks like a really old Radio Spares (RS) logo.

Click on the chart to see a movie of this in action! However, as it is encoded in MPEG and it looks slightly corrupted on a Digibox, you can't expect much!

Taken: 1999

This one's a blast from the past, as I'm sure the BBC used to show something similar to this many years ago.

Taken: 1999

Purple
Test CDTA

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I can't remember when I took this one, but it's unusual as UK Gold are usually either broadcasting programmes or showing Screenshop.  There is a UK Gold bug in the corner.

"CDTA" is the Commercial Digital Transmission Area at Television Centre where the UKTVand Worldwide Channels come from.

Taken: 1999



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