Color bar / Test pattern question

[Zach Legleiter]

Hello All,

I was watching a live sporting event on a local television channel today. The broadcast had ended and had faded to black for about a minute. Then there was color bars on screen with tone for about 30 seconds, until a set of commercials played, and a new program started.

What was different from what i was used to about the color bars was that there was a small white box overlaid on top of the color bars bouncing from top to bottom every one second or so. Then overlaid atop everything was the normal character ID.

Does anyone know what the bouncing white box is? what is it called? and what is it's purpose? Nothing major, just curious. I have never seen this before.

Thanks!! Merry Christmas!!

[David Heath]

Originally Posted by Zach Legleiter

Does anyone know what the bouncing white box is? what is it called? and what is it's purpose? Nothing major, just curious. I have never seen this before.

Thanks!! Merry Christmas!!

People have been caught out when a live feed goes away by their decoder showing a still frame. (Unlike in analogue link days.) They see bars and ident and assume they are still receiving a signal.

By having movement of some sort within the frame, it stops the confusion. Signal goes away, freeze frame, and ball stops. A clue to be getting on the phone to whoever is sending the signal to you.

[Zach Legleiter]

Here is an example of what i saw:

Bouncing box/color bars - YouTube

[Jody Arnott]

Originally Posted by Zach Legleiter

Hello All,

I was watching a live sporting event on a local television channel today. The broadcast had ended and had faded to black for about a minute. Then there was color bars on screen with tone for about 30 seconds, until a set of commercials played, and a new program started.

What was different from what i was used to about the color bars was that there was a small white box overlaid on top of the color bars bouncing from top to bottom every one second or so. Then overlaid atop everything was the normal character ID.

Does anyone know what the bouncing white box is? what is it called? and what is it's purpose? Nothing major, just curious. I have never seen this before.

Thanks!! Merry Christmas!!

I saw that every day when I worked in broadcast but never thought to ask what it was for.

I could guess.. maybe it's used to check the waveform and vector scopes are working as it shows movement? I'm probably wrong though :P

[David Heath]

Originally Posted by Jody Arnott

I could guess.. maybe it's used to check the waveform and vector scopes are working as it shows movement? I'm probably wrong though :P

Seeing the posted image, I'm pretty sure my answer is correct - as long as the box is moving, it's showing you're receiving a proper signal. If you see a stationary box, you've lost the signal and the decoder is just showing a freeze frame from the time it went away.